{"title":"XPS INSULATION BOARDS","description":"\u003cp\u003eWithin the \u003ca href=\"\/collections\/ewi-systems-1\"\u003eexternal wall insulation systems\u003c\/a\u003e range, XPS insulation boards handle the moisture, ground pressure, and freeze-thaw cycling that standard EPS cannot. The Atlas Fundament range stocked at Renders World spans five thicknesses from 30 mm to 100 mm, each engineered with a closed-cell structure purpose-built for foundations, plinths, and below-DPC zones where ground contact and hydrostatic pressure would compromise open-cell insulation.\u003c\/p\u003e\n\u003ch2 id=\"where-xps-insulation-boards-perform-best-uk-foundation-and-plinth-zones\"\u003eWhere XPS Insulation Boards Perform Best — UK Foundation and Plinth Zones\u003c\/h2\u003e\n\u003cp\u003eXPS insulation boards eliminate thermal loss where walls meet the ground, with the Atlas Fundament range delivering λ 0.038 W\/mK across 30–100 mm thicknesses for foundations, plinths, and below-DPC zones. The closed-cell density structure achieves near-zero long-term water absorption, making it the reliable choice for foundation walls up to 2 m below ground level, plinth zones beneath the damp-proof course, basement perimeters, and floors in damp rooms such as cellars and utility spaces. Each board measures 600 × 1250 mm with rebated edges for tight, thermal-bridge-free joints — so the insulation line stays continuous from footing to DPC.\u003c\/p\u003e\n\u003cp\u003eAbove the damp-proof course the situation changes: the main facade typically benefits from \u003ca href=\"\/collections\/eps-insulation-boards\"\u003egraphite EPS boards\u003c\/a\u003e for their vapour permeability, while XPS remains the superior choice for every below-ground and splash-zone application.\u003c\/p\u003e\n\u003ch2 id=\"what-makes-xps-foundation-boards-worth-specifying\"\u003eWhat Makes XPS Foundation Boards Worth Specifying\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePermanent moisture protection:\u003c\/strong\u003e The closed-cell structure prevents water absorption even under sustained hydrostatic pressure, so thermal performance stays constant for the lifetime of the foundation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh compressive strength:\u003c\/strong\u003e Foundation-grade XPS typically resists backfill pressure, domestic floor loads, and soil movement without deformation — supporting driveways, paths, and heavy landscaping when specified to the project's structural load value (confirmed via TDS at order).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFreeze-thaw stability:\u003c\/strong\u003e XPS holds its full R-value through repeated freeze-thaw cycles typical of UK winters, delivering consistent thermal protection in exposed ground-contact positions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBiological resistance:\u003c\/strong\u003e Naturally resistant to mould, fungi, and soil bacteria, the boards keep structural integrity underground without chemical treatment — a useful margin in damp clay and loam soils common across the UK.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrecise, low-waste installation:\u003c\/strong\u003e Rebated edges slot together to form a continuous insulation plane, reducing on-site cutting waste and speeding up foundation work. Each board covers 0.75 m², and the standard 600 × 1250 mm size simplifies ordering calculations.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"selection-guide-find-your-xps-thickness-in-30-seconds\"\u003eSelection Guide — Find Your XPS Thickness in 30 Seconds\u003c\/h2\u003e\n\u003cblockquote\u003eIdentify the wall zone and depth, read across to the matching Atlas Fundament board, then check the R-value against your project's U-value target. For mixed builds, pair plinth XPS with EPS or mineral wool above DPC.\u003c\/blockquote\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eYour Project Zone\u003c\/th\u003e\n\u003cth\u003eBest Board\u003c\/th\u003e\n\u003cth\u003eStandout Spec\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eThin plinth upgrade, screed underlay\u003c\/td\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-30mm-1-board-0-038w\"\u003eAtlas Fundament 30 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003eR 0.79 · λ 0.038 · 0.75 m²\/board\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFloor insulation, shallow foundation wrap\u003c\/td\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-50mm-1-board-0-038w\"\u003eAtlas Fundament 50 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003eR 1.32 · 600 × 1250 mm · rebated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStandard foundation and basement walls\u003c\/td\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003eR 2.11 · closed-cell · foundation-grade\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBelow-DPC plinth with render above\u003c\/td\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-90mm-1-board-0-038w\"\u003eAtlas Fundament 90 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003eR 2.37 · freeze-thaw stable\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDeep foundation wrap, highest thermal target\u003c\/td\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003eAtlas Fundament 100 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003eR 2.63 · 100 mm · full ground wrap\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"how-xps-boards-install-in-a-uk-foundation-or-plinth-build-up\"\u003eHow XPS Boards Install in a UK Foundation or Plinth Build-Up\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament boards bond best to clean, level, waterproofed substrates using a specialist polyurethane adhesive such as \u003ca href=\"\/products\/ceresit-ct84-xps-foam-850ml\"\u003eCeresit CT84 XPS Foam\u003c\/a\u003e, which cures fast and tolerates the cool, damp conditions typical of UK ground-level work. Above-ground plinth sections also benefit from additional \u003ca href=\"\/collections\/fixing-accesories\"\u003emechanical fixings\u003c\/a\u003e to resist wind uplift and lock long-term bond security.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFoundation walls:\u003c\/strong\u003e Apply boards vertically against the external face of the basement or foundation wall, from footing level up to the damp-proof course. Backfill provides permanent mechanical restraint.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlinth zones:\u003c\/strong\u003e Position XPS from ground level up to the DPC line, then transition to EPS or mineral wool above. A starter track at the junction keeps the insulation line true.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFloor and cellar insulation:\u003c\/strong\u003e Lay boards horizontally beneath screed in cellars, utility rooms, and ground-floor extensions. The high compressive strength supports standard domestic floor loads without extra reinforcement.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDamp rooms:\u003c\/strong\u003e Washrooms, cellars, and unheated garages gain thermal and moisture protection simultaneously, lowering condensation risk on cold walls.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"what-uk-installers-do-differently-with-xps-boards\"\u003eWhat UK Installers Do Differently With XPS Boards\u003c\/h2\u003e\n\u003cp\u003eExperienced installers fit Atlas Fundament boards foundation-side first, working upward from the footing in staggered horizontal courses so every joint is locked against thermal bridging. For the cleanest result, score the rebated edge with a fine-tooth saw rather than snapping it: the closed-cell surface stays intact, the rebate stays true, and the adhesive bond area stays at its maximum.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eStagger every course:\u003c\/strong\u003e Offset vertical joints by at least 200 mm between rows so no four-corner joint forms a continuous cold path.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOverlap the plinth-to-facade transition by 100 mm minimum:\u003c\/strong\u003e A short XPS-over-EPS overlap at the DPC line shuts down the cold bridge that drives \u003ca href=\"\/blogs\/news\/thermal-bridges-plinth-insulation-mould-prevention\"\u003emould at the plinth junction\u003c\/a\u003e, a step worth getting right to keep the base of the wall dry for decades.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccount for cool-weather cure:\u003c\/strong\u003e CT84 foam adhesive cures more slowly when ambient temperatures drop below about 5 °C — plan board placement so freshly bonded sections are not disturbed for at least the manufacturer's stated cure window.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProtect from prolonged UV:\u003c\/strong\u003e XPS is sensitive to long sun exposure on site; cover stacked boards under sheeting if storage exceeds a few weeks.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"is-this-xps-range-right-for-your-project\"\u003eIs This XPS Range Right for Your Project?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose this range if\u003c\/strong\u003e your project involves foundation walls, plinth zones below DPC, basement perimeters, or any application where the insulation sits in permanent contact with ground moisture, splash-back, or hydrostatic pressure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNeed a full XPS-vs-EPS view before deciding?\u003c\/strong\u003e The \u003ca href=\"\/blogs\/news\/xps-vs-eps-insulation-uk\"\u003eXPS vs EPS comparison for UK projects\u003c\/a\u003e walks through where each material wins and the build-up implications.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAbove-ground facade work?\u003c\/strong\u003e \u003ca href=\"\/collections\/eps-insulation-boards\"\u003eGraphite EPS boards\u003c\/a\u003e within the same EWI range deliver the vapour permeability and lighter weight that external render systems need on the main elevation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNon-combustible route required?\u003c\/strong\u003e \u003ca href=\"\/collections\/mineral-wool-rockwool\"\u003eNon-combustible mineral wool insulation for high-rise and fire-strategy projects\u003c\/a\u003e provides Euroclass A1 performance and is typically preferred where the project fire strategy requires non-combustible insulation above ground level.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"faq-xps-board-installation-and-compatibility\"\u003eFAQ — XPS Board Installation and Compatibility\u003c\/h2\u003e\n\u003ch3 id=\"how-much-do-xps-foundation-boards-cost-compared-to-standard-eps\"\u003eHow much do XPS foundation boards cost compared to standard EPS?\u003c\/h3\u003e\n\u003cp\u003eXPS carries a higher unit cost than expanded polystyrene because the extrusion process creates the closed-cell structure that resists water absorption. For below-ground and plinth applications, total installed cost is often competitive because XPS removes the need for a separate drainage membrane and delivers longer maintenance-free performance in permanently damp conditions.\u003c\/p\u003e\n\u003ch3 id=\"are-xps-insulation-boards-recyclable\"\u003eAre XPS insulation boards recyclable?\u003c\/h3\u003e\n\u003cp\u003eExtruded polystyrene is a thermoplastic and can be recycled at facilities that accept rigid foam. Off-cuts generated during installation can be returned to specialist recyclers, and modern Atlas Fundament boards contain no ozone-depleting blowing agents. For projects targeting BREEAM credits, XPS contributes positively to the waste management plan when a closed-loop return route is established with the supplier.\u003c\/p\u003e\n\u003ch3 id=\"can-i-use-xps-boards-on-the-main-facade-above-dpc\"\u003eCan I use XPS boards on the main facade above DPC?\u003c\/h3\u003e\n\u003cp\u003eXPS is designed for foundation and plinth zones because its closed-cell structure limits vapour permeability — moisture trapped behind a render finish above DPC has limited escape routes. For the main facade, graphite EPS or mineral wool provides the breathability that external render systems rely on to keep walls dry and condensation-free over the long term.\u003c\/p\u003e\n\u003ch3 id=\"what-xps-thickness-meets-part-l-for-uk-ground-floors\"\u003eWhat XPS thickness meets Part L for UK ground floors?\u003c\/h3\u003e\n\u003cp\u003eThe thickness needed depends on the existing floor construction, ground conditions, and the overall U-value target set by the project's energy assessment. In many standard domestic configurations, 80 mm to 100 mm of XPS (R-value 2.11–2.63 m²K\/W) brings a solid ground floor within the range typically required to meet Approved Document L 2021 targets (current at time of writing), subject to a project-specific U-value calculation.\u003c\/p\u003e\n\u003ch3 id=\"do-xps-boards-need-mechanical-fixings-as-well-as-adhesive\"\u003eDo XPS boards need mechanical fixings as well as adhesive?\u003c\/h3\u003e\n\u003cp\u003eBelow ground level, backfill provides permanent mechanical restraint and the polyurethane foam adhesive alone is typically sufficient. Above ground — particularly on plinth zones exposed to wind uplift or where a render finish will be applied — adding mechanical fixings at 6–8 plugs per m² (project-specific, per fixing layout) is the standard approach for long-term bond security.\u003c\/p\u003e\n\u003ch3 id=\"how-many-xps-boards-do-i-need-per-square-metre\"\u003eHow many XPS boards do I need per square metre?\u003c\/h3\u003e\n\u003cp\u003eEach Atlas Fundament board covers 0.75 m² (600 × 1250 mm), so 1.33 boards per m² is the base figure. Add roughly 5–10% for cutting waste around corners, openings, and rebated overlaps, then round up to the nearest full board when placing the order.\u003c\/p\u003e","products":[{"product_id":"eps-foundation-30mm-1-board-0-038w","title":"EPS FOUNDATION 30mm (1 BOARD) 0.038W","description":"\u003cp\u003eWithin the \u003ca href=\"\/collections\/xps-insulationboards\"\u003eXPS insulation boards\u003c\/a\u003e range, Atlas Fundament 30 mm is the thinnest board in the Genderka foundation series — engineered for thin plinth upgrades, screed underlay applications, and tight reveal zones where every millimetre of depth matters. The board delivers a thermal conductivity of \u003cstrong\u003eλ 0.038 W\/mK\u003c\/strong\u003e in a closed-cell foundation-grade structure, measuring 600 × 1250 mm with rebated edges and covering 0.75 m² per board.\u003c\/p\u003e\n\u003ch2 id=\"what-atlas-fundament-30mm-does-in-a-uk-ewi-system\"\u003eWhat Atlas Fundament 30 mm Does in a UK EWI System\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 30 mm bridges the gap between a vapour-permeable EPS facade and the wet zone below the damp-proof course, delivering λ 0.038 W\/mK in a closed-cell foundation board engineered for permanent ground-contact conditions. The 30 mm thickness is purpose-built for shallow applications — screed underlay in cellars and utility rooms, thin plinth upgrades on retrofit projects, and reveal-to-foundation junctions where deeper XPS would clash with adjacent EPS courses on the main facade.\u003c\/p\u003e\n\u003cp\u003eEach board measures 600 × 1250 mm with rebated edges that lock together to form a continuous insulation plane without thermal bridging at the joints — so the moisture-resistant layer reads as a single membrane from one course to the next.\u003c\/p\u003e\n\u003ch2 id=\"why-specifiers-choose-atlas-fundament-30mm-for-uk-walls\"\u003eWhy Specifiers Choose Atlas Fundament 30 mm for UK Walls\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSlimmest profile in the range:\u003c\/strong\u003e At 30 mm, the board fits in screed build-ups, thin plinth upgrades, and reveal zones where 50 mm or thicker boards would protrude past the finished line.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClosed-cell moisture protection:\u003c\/strong\u003e Permanent resistance to ground moisture and hydrostatic pressure keeps thermal performance constant for the life of the foundation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRebated edges for joint integrity:\u003c\/strong\u003e Tight overlapping joints reduce the cold-bridge risk that flat-edge boards leave at every horizontal course.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFreeze-thaw stable:\u003c\/strong\u003e Holds full R-value through repeated UK winter cycles in exposed ground-contact and splash-zone positions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLow-waste sizing:\u003c\/strong\u003e 600 × 1250 mm covers 0.75 m² per board, simplifying take-off calculations for narrow plinth runs and screed strips.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"thermal-specifications-atlas-fundament-30mm\"\u003eThermal Specifications — Atlas Fundament 30 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal conductivity (λ)\u003c\/td\u003e\n\u003ctd\u003e0.038 W\/mK\u003c\/td\u003e\n\u003ctd\u003eDeclared value for foundation board\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThickness\u003c\/td\u003e\n\u003ctd\u003e30 mm\u003c\/td\u003e\n\u003ctd\u003eThinnest in Atlas Fundament range\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal resistance (R)\u003c\/td\u003e\n\u003ctd\u003e0.79 m²K\/W\u003c\/td\u003e\n\u003ctd\u003eAt declared λ × thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReaction to fire\u003c\/td\u003e\n\u003ctd\u003ePer EN 13501-1\u003c\/td\u003e\n\u003ctd\u003eConfirm via current DoP at order\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater absorption\u003c\/td\u003e\n\u003ctd\u003eLow (closed-cell)\u003c\/td\u003e\n\u003ctd\u003eSuitable for permanent ground contact\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"physical-specifications-atlas-fundament-30mm\"\u003ePhysical Specifications — Atlas Fundament 30 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoard dimensions\u003c\/td\u003e\n\u003ctd\u003e600 × 1250 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoverage per board\u003c\/td\u003e\n\u003ctd\u003e0.75 m²\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEdge profile\u003c\/td\u003e\n\u003ctd\u003eRebated (lap joint)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompressive strength\u003c\/td\u003e\n\u003ctd\u003eFoundation-grade (confirm via TDS at order)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoards per m²\u003c\/td\u003e\n\u003ctd\u003e1.33 (add 5–10% cutting waste)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"where-atlas-fundament-30mm-performs-best-wall-types-and-build-up\"\u003eWhere Atlas Fundament 30 mm Performs Best — Wall Types \u0026amp; Build-Up\u003c\/h2\u003e\n\u003cp\u003eThe 30 mm thickness sits at the shallow end of foundation insulation. Three application contexts make best use of it: screed underlay where floor build-up height is restricted, thin plinth upgrades on existing renders where the protrusion of thicker boards would force facade rework, and reveal zones at the foundation-to-window junction where insulation must thread through tight detailing without overlap clashes.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eScreed underlay in cellars and utility rooms:\u003c\/strong\u003e Lay horizontally over a level slab, then pour screed directly above — the closed-cell surface tolerates the wet trade without water uptake.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThin plinth upgrades on retrofit:\u003c\/strong\u003e Fit vertically over an existing plinth substrate where deeper insulation would force the DPC line and render finish out of plumb with the facade above.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReveal and junction zones:\u003c\/strong\u003e Use as a thin thermal break at foundation-to-reveal transitions where a deeper board would clash with adjacent EPS courses.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBelow-DPC capping strips:\u003c\/strong\u003e Cap exposed concrete kickers or footing tops where a thicker board would project past the facade plane.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"how-atlas-fundament-30mm-fits-into-a-full-ewi-system\"\u003eHow Atlas Fundament 30 mm Fits Into a Full EWI System\u003c\/h2\u003e\n\u003cp\u003eIn a full external wall insulation build-up, Atlas Fundament 30 mm typically sits in the plinth or floor zone below the damp-proof course, while the main facade above DPC is finished with \u003ca href=\"\/collections\/eps-insulation-boards\"\u003egraphite EPS boards\u003c\/a\u003e bonded with adhesive-and-basecoat and finished with mesh-reinforced render. Bond the 30 mm board with a specialist polyurethane adhesive such as \u003ca href=\"\/products\/ceresit-ct84-xps-foam-850ml\"\u003eCeresit CT84 XPS Foam\u003c\/a\u003e, which cures fast in the cool, damp conditions typical of UK ground-level work.\u003c\/p\u003e\n\u003cp\u003eAbove ground level — particularly on plinth zones exposed to wind uplift — add mechanical fixings from the \u003ca href=\"\/collections\/fixing-accesories\"\u003eEWI fixing accessories range\u003c\/a\u003e to lock long-term bond security. Below ground, backfill provides permanent mechanical restraint and the foam adhesive alone is typically sufficient.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-30mm-compares-to-sibling-foundation-boards\"\u003eHow Atlas Fundament 30 mm Compares to Sibling Foundation Boards\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBoard\u003c\/th\u003e\n\u003cth\u003eThickness\u003c\/th\u003e\n\u003cth\u003eR-Value (m²K\/W)\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAtlas Fundament 30 mm\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e30 mm\u003c\/td\u003e\n\u003ctd\u003e0.79\u003c\/td\u003e\n\u003ctd\u003eScreed underlay, thin plinth, reveal zones\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-50mm-1-board-0-038w\"\u003eAtlas Fundament 50 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003ctd\u003e1.32\u003c\/td\u003e\n\u003ctd\u003eFloor insulation, shallow foundation wrap\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e80 mm\u003c\/td\u003e\n\u003ctd\u003e2.11\u003c\/td\u003e\n\u003ctd\u003eStandard foundation and basement walls\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003eAtlas Fundament 100 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e100 mm\u003c\/td\u003e\n\u003ctd\u003e2.63\u003c\/td\u003e\n\u003ctd\u003eDeep foundation wrap, highest thermal target\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eFor projects weighing closed-cell foundation insulation against graphite EPS for the main facade, the \u003ca href=\"\/blogs\/news\/xps-vs-eps-insulation-uk\"\u003eXPS vs EPS comparison guide\u003c\/a\u003e walks through where each material wins across the build-up.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-30mm-performs-in-uk-weather\"\u003eHow Atlas Fundament 30 mm Performs in UK Weather — Moisture, Frost, Wind Loads\u003c\/h2\u003e\n\u003cp\u003eThe closed-cell structure keeps long-term water absorption at near-zero, so freeze-thaw cycling across a typical UK winter does not progressively reduce R-value the way it can on open-cell boards exposed to ground moisture. In splash-zone and below-grade positions, the board holds its thermal performance through saturation, drying, and re-saturation cycles for decades.\u003c\/p\u003e\n\u003cp\u003eAt 30 mm thickness, wind-load exposure is rarely the governing factor — the board is typically protected by backfill below grade, or by render and mesh above DPC on plinth zones. Where wind uplift is a concern (exposed plinth runs on tall facades, coastal sites), add mechanical fixings at 6–8 plugs per m² per the project's fixing layout.\u003c\/p\u003e\n\u003ch2 id=\"handling-and-storage-on-site\"\u003eHandling \u0026amp; Storage on Site\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eKeep dry and shaded:\u003c\/strong\u003e Stack boards flat on a clean, level surface. Cover with sheeting if outdoor storage exceeds a few weeks — prolonged UV softens the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eScore, don't snap:\u003c\/strong\u003e Cut with a fine-tooth saw or sharp blade rather than snapping the rebated edge. A clean cut keeps the bonding face true and protects the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrush the rebate before adhesive:\u003c\/strong\u003e Dust on the lap joint breaks the foam adhesive seal; a quick brush gives a full-face bond.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStack flat, not on edge:\u003c\/strong\u003e Storing 30 mm boards on edge can cause bowing — flat storage preserves the rebated geometry.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"certifications-and-compliance-atlas-fundament-30mm\"\u003eCertifications \u0026amp; Compliance — Atlas Fundament 30 mm\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament boards are manufactured to recognised European foundation insulation standards. Reaction to fire is classified under EN 13501-1, and the declared thermal conductivity (λ 0.038 W\/mK) appears on the manufacturer's current Declaration of Performance. For projects requiring specific compressive strength values, water absorption test results, or Approved Document L 2021 calculation inputs (current at time of writing), request the latest DoP at order — exact certified values can vary between production batches and the current Atlas Fundament datasheet is the authoritative reference.\u003c\/p\u003e\n\u003ch2 id=\"is-atlas-fundament-30mm-right-for-your-project\"\u003eIs Atlas Fundament 30 mm Right for Your Project?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose this thickness if\u003c\/strong\u003e your project needs a thin foundation board for screed underlay, plinth upgrades on existing render, or reveal-zone thermal breaks where deeper boards would clash with adjacent insulation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNeed more depth for a full foundation wrap?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e covers standard foundation and basement walls at R 2.11 m²K\/W, and the \u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003e100 mm version\u003c\/a\u003e hits R 2.63 for the highest thermal target in the range.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWorking above DPC?\u003c\/strong\u003e Switch to \u003ca href=\"\/collections\/eps-insulation-boards\"\u003egraphite EPS boards\u003c\/a\u003e for vapour permeability on the main facade.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDetailing the plinth-to-facade transition?\u003c\/strong\u003e The \u003ca href=\"\/blogs\/news\/thermal-bridges-plinth-insulation-mould-prevention\"\u003eplinth thermal-bridge guide\u003c\/a\u003e walks through the 100 mm overlap detail that keeps the DPC line condensation-free.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"what-to-order-next-pack-sizes-lead-times-compatible-components\"\u003eWhat to Order Next — Pack Sizes, Lead Times, Compatible Components\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 30 mm is supplied as a single board (0.75 m² coverage). For project calculations, allow 1.33 boards per m² plus 5–10% cutting waste. To complete the foundation build-up, order Ceresit CT84 XPS Foam for bonding and a fixing pattern of 6–8 plugs per m² above grade for wind-uplift resistance.\u003c\/p\u003e\n\u003ch2 id=\"faq-atlas-fundament-30mm-coverage-compatibility-installation\"\u003eFAQ — Atlas Fundament 30 mm Coverage, Compatibility, Installation\u003c\/h2\u003e\n\u003ch3 id=\"how-many-30mm-atlas-fundament-boards-do-i-need-per-square-metre\"\u003eHow many 30 mm Atlas Fundament boards do I need per square metre?\u003c\/h3\u003e\n\u003cp\u003eEach board covers 0.75 m² (600 × 1250 mm), so 1.33 boards per m² is the base figure. For typical plinth and screed-underlay runs, add 5–10% cutting waste for corners, openings, and rebated overlaps, then round up to the nearest full board.\u003c\/p\u003e\n\u003ch3 id=\"is-30mm-thick-enough-for-a-full-foundation-wrap\"\u003eIs 30 mm thick enough for a full foundation wrap?\u003c\/h3\u003e\n\u003cp\u003eFor a full foundation wrap targeting modern thermal performance, 30 mm is typically insufficient on its own — most domestic foundation specifications sit at 80 mm to 100 mm to meet current U-value targets. The 30 mm board is purpose-built for shallow contexts: screed underlay, thin plinth upgrades on retrofits, and reveal-zone thermal breaks where deeper boards would clash with the facade detailing above.\u003c\/p\u003e\n\u003ch3 id=\"what-adhesive-bonds-atlas-fundament-30mm-to-a-foundation-wall\"\u003eWhat adhesive bonds Atlas Fundament 30 mm to a foundation wall?\u003c\/h3\u003e\n\u003cp\u003eA specialist polyurethane adhesive such as Ceresit CT84 XPS Foam is the standard route — it cures fast in cool, damp UK ground-level conditions and bonds reliably to closed-cell board surfaces. Apply in continuous beads around the perimeter plus a central bead, brush dust from the rebated edge before placement, and press firmly to spread the foam across the full bonding face.\u003c\/p\u003e\n\u003ch3 id=\"can-i-use-30mm-atlas-fundament-on-a-facade-above-dpc\"\u003eCan I use 30 mm Atlas Fundament on a facade above DPC?\u003c\/h3\u003e\n\u003cp\u003eThe closed-cell structure limits vapour permeability, so the main facade above DPC typically benefits from graphite EPS or mineral wool rather than foundation-grade board. The 30 mm Atlas Fundament earns its place at the plinth, screed, and below-DPC zones where its moisture resistance is the deciding factor.\u003c\/p\u003e\n\u003ch3 id=\"does-30mm-need-mechanical-fixings-as-well-as-adhesive\"\u003eDoes 30 mm need mechanical fixings as well as adhesive?\u003c\/h3\u003e\n\u003cp\u003eBelow ground level, backfill provides permanent mechanical restraint and the polyurethane foam adhesive alone is typically sufficient. Above grade on exposed plinth runs, add mechanical fixings at 6–8 plugs per m² per the project's fixing layout to resist wind uplift and lock long-term bond security.\u003c\/p\u003e\n\u003ch3 id=\"how-does-30mm-compare-thermally-to-50mm-atlas-fundament\"\u003eHow does 30 mm compare thermally to 50 mm Atlas Fundament?\u003c\/h3\u003e\n\u003cp\u003eAt the same declared λ of 0.038 W\/mK, the 30 mm board delivers R 0.79 m²K\/W and the \u003ca href=\"\/products\/eps-foundation-50mm-1-board-0-038w\"\u003e50 mm Atlas Fundament\u003c\/a\u003e delivers R 1.32 — a 67% uplift in thermal resistance for an extra 20 mm of depth. Where the build-up has room for it, the 50 mm version is the stronger choice; where every millimetre matters, the 30 mm board is the only fit.\u003c\/p\u003e","brand":"Renders World","offers":[{"title":"Default Title","offer_id":56400714989943,"sku":null,"price":4.8,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0973\/1375\/1415\/files\/aqua-poliester-eps-board_9833a88d-449d-42b6-bbbf-ff5ac6142049.jpg?v=1767042902"},{"product_id":"eps-foundation-50mm-1-board-0-038w","title":"EPS FOUNDATION 50mm (1 BOARD) 0.038W","description":"\u003cp\u003eWithin the \u003ca href=\"\/collections\/xps-insulationboards\"\u003eXPS insulation boards\u003c\/a\u003e range, Atlas Fundament 50 mm sits at the mid-range entry point where foundation insulation starts delivering meaningful thermal payoff. The board delivers a thermal conductivity of \u003cstrong\u003eλ 0.038 W\/mK\u003c\/strong\u003e in a closed-cell foundation-grade structure, measuring 600 × 1250 mm with rebated edges and covering 0.75 m² per board — purpose-built for floor insulation under screed, shallow foundation wraps, and plinth zones where the build-up has room for proper depth.\u003c\/p\u003e\n\u003ch2 id=\"what-atlas-fundament-50mm-does-in-a-uk-ewi-system\"\u003eWhat Atlas Fundament 50 mm Does in a UK EWI System\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 50 mm is the first thickness in the foundation range that delivers a thermal resistance most domestic projects can plan around — R 1.32 m²K\/W in a closed-cell board engineered for permanent ground-contact conditions. The 50 mm depth opens up floor insulation under screed in cellars and ground-floor extensions, shallow foundation wraps on lighter domestic builds, and plinth zones where the facade detailing above DPC can absorb the extra projection without forcing the render line out of plumb.\u003c\/p\u003e\n\u003cp\u003eEach board measures 600 × 1250 mm with rebated edges that lock together to form a continuous insulation plane without thermal bridging at the joints — so the moisture-resistant layer reads as a single membrane from one course to the next.\u003c\/p\u003e\n\u003ch2 id=\"why-specifiers-choose-atlas-fundament-50mm-for-uk-walls\"\u003eWhy Specifiers Choose Atlas Fundament 50 mm for UK Walls\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFirst thickness with meaningful R-value:\u003c\/strong\u003e At R 1.32 m²K\/W, the 50 mm board nearly doubles the thermal resistance of the 30 mm variant — the depth where foundation insulation starts contributing measurably to overall U-values.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClosed-cell moisture protection:\u003c\/strong\u003e Permanent resistance to ground moisture and hydrostatic pressure keeps thermal performance constant for the life of the foundation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRebated edges for joint integrity:\u003c\/strong\u003e Tight overlapping joints reduce the cold-bridge risk that flat-edge boards leave at every horizontal course.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFreeze-thaw stable:\u003c\/strong\u003e Holds full R-value through repeated UK winter cycles in exposed ground-contact and splash-zone positions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePredictable take-off:\u003c\/strong\u003e 600 × 1250 mm covers 0.75 m² per board, so 1.33 boards per m² makes coverage calculations straightforward for shallow foundation runs and floor strips.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"thermal-specifications-atlas-fundament-50mm\"\u003eThermal Specifications — Atlas Fundament 50 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal conductivity (λ)\u003c\/td\u003e\n\u003ctd\u003e0.038 W\/mK\u003c\/td\u003e\n\u003ctd\u003eDeclared value for foundation board\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThickness\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003ctd\u003eMid-range Atlas Fundament thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal resistance (R)\u003c\/td\u003e\n\u003ctd\u003e1.32 m²K\/W\u003c\/td\u003e\n\u003ctd\u003eAt declared λ × thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReaction to fire\u003c\/td\u003e\n\u003ctd\u003ePer EN 13501-1\u003c\/td\u003e\n\u003ctd\u003eConfirm via current DoP at order\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater absorption\u003c\/td\u003e\n\u003ctd\u003eLow (closed-cell)\u003c\/td\u003e\n\u003ctd\u003eSuitable for permanent ground contact\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"physical-specifications-atlas-fundament-50mm\"\u003ePhysical Specifications — Atlas Fundament 50 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoard dimensions\u003c\/td\u003e\n\u003ctd\u003e600 × 1250 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoverage per board\u003c\/td\u003e\n\u003ctd\u003e0.75 m²\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEdge profile\u003c\/td\u003e\n\u003ctd\u003eRebated (lap joint)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompressive strength\u003c\/td\u003e\n\u003ctd\u003eFoundation-grade (confirm via TDS at order)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoards per m²\u003c\/td\u003e\n\u003ctd\u003e1.33 (add 5–10% cutting waste)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"where-atlas-fundament-50mm-performs-best-wall-types-and-build-up\"\u003eWhere Atlas Fundament 50 mm Performs Best — Wall Types \u0026amp; Build-Up\u003c\/h2\u003e\n\u003cp\u003eThe 50 mm thickness sits at the point where foundation insulation transitions from \"thin retrofit fix\" to \"specifiable thermal layer\". Three application contexts make best use of it: floor insulation under screed where the slab build-up has 50 mm of headroom, shallow foundation wraps on lighter domestic builds where deeper backfill insulation would be over-specified, and plinth zones beneath DPC where the facade above can absorb the extra projection without disrupting the render line.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFloor insulation under screed:\u003c\/strong\u003e Lay horizontally over a level slab in cellars, ground-floor extensions, and utility rooms. The 50 mm depth balances R-value with screed build-up height for typical domestic floors.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShallow foundation wraps:\u003c\/strong\u003e Fit vertically against the external face of foundation walls on lighter domestic builds where deeper boards would over-specify the thermal target.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlinth zones with render finish above:\u003c\/strong\u003e Position from ground level up to the DPC line on new-build projects where the facade detailing is being set fresh and can plan around the 50 mm projection.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGarage and utility-room walls:\u003c\/strong\u003e Insulate unheated spaces where thermal performance matters but a deeper board is hard to justify on cost.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"how-atlas-fundament-50mm-fits-into-a-full-ewi-system\"\u003eHow Atlas Fundament 50 mm Fits Into a Full EWI System\u003c\/h2\u003e\n\u003cp\u003eIn a full external wall insulation build-up, Atlas Fundament 50 mm typically handles the plinth or floor zone below DPC, while the main facade above is finished with \u003ca href=\"\/collections\/eps-insulation-boards\"\u003egraphite EPS boards\u003c\/a\u003e bonded with adhesive-and-basecoat and finished with mesh-reinforced render. Bond the 50 mm board with a specialist polyurethane adhesive such as \u003ca href=\"\/products\/ceresit-ct84-xps-foam-850ml\"\u003eCeresit CT84 XPS Foam\u003c\/a\u003e, which cures fast in the cool, damp conditions typical of UK ground-level work.\u003c\/p\u003e\n\u003cp\u003eAbove ground level — particularly on plinth zones exposed to wind uplift — add mechanical fixings from the \u003ca href=\"\/collections\/fixing-accesories\"\u003eEWI fixing accessories range\u003c\/a\u003e to lock long-term bond security. Below ground, backfill provides permanent mechanical restraint and the foam adhesive alone is typically sufficient for the 50 mm board.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-50mm-compares-to-sibling-foundation-boards\"\u003eHow Atlas Fundament 50 mm Compares to Sibling Foundation Boards\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBoard\u003c\/th\u003e\n\u003cth\u003eThickness\u003c\/th\u003e\n\u003cth\u003eR-Value (m²K\/W)\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-30mm-1-board-0-038w\"\u003eAtlas Fundament 30 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e30 mm\u003c\/td\u003e\n\u003ctd\u003e0.79\u003c\/td\u003e\n\u003ctd\u003eScreed underlay, thin plinth, reveal zones\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAtlas Fundament 50 mm\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003ctd\u003e1.32\u003c\/td\u003e\n\u003ctd\u003eFloor insulation, shallow foundation wrap, light-domestic plinth\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e80 mm\u003c\/td\u003e\n\u003ctd\u003e2.11\u003c\/td\u003e\n\u003ctd\u003eStandard foundation and basement walls\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003eAtlas Fundament 100 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e100 mm\u003c\/td\u003e\n\u003ctd\u003e2.63\u003c\/td\u003e\n\u003ctd\u003eDeep foundation wrap, highest thermal target\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eFor projects weighing closed-cell foundation insulation against graphite EPS for the main facade, the \u003ca href=\"\/blogs\/news\/xps-vs-eps-insulation-uk\"\u003eXPS vs EPS comparison guide\u003c\/a\u003e walks through where each material wins across the build-up.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-50mm-performs-in-uk-weather\"\u003eHow Atlas Fundament 50 mm Performs in UK Weather — Moisture, Frost, Wind Loads\u003c\/h2\u003e\n\u003cp\u003eThe closed-cell structure keeps long-term water absorption at near-zero, so freeze-thaw cycling across a typical UK winter does not progressively reduce R-value the way it can on open-cell boards exposed to ground moisture. In splash-zone and below-grade positions, the 50 mm board holds its thermal performance through saturation, drying, and re-saturation cycles for decades.\u003c\/p\u003e\n\u003cp\u003eWind-load exposure becomes a meaningful factor at the 50 mm depth above grade: the increased face area catches uplift on exposed plinth runs more readily than the 30 mm board does. On tall facades, coastal sites, or any plinth zone where wind exposure is significant, add mechanical fixings at 6–8 plugs per m² per the project's fixing layout.\u003c\/p\u003e\n\u003ch2 id=\"handling-and-storage-on-site\"\u003eHandling \u0026amp; Storage on Site\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eKeep dry and shaded:\u003c\/strong\u003e Stack boards flat on a clean, level surface. Cover with sheeting if outdoor storage exceeds a few weeks — prolonged UV softens the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eScore, don't snap:\u003c\/strong\u003e Cut with a fine-tooth saw or sharp blade rather than snapping the rebated edge. A clean cut keeps the bonding face true and protects the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrush the rebate before adhesive:\u003c\/strong\u003e Dust on the lap joint breaks the foam adhesive seal; a quick brush gives a full-face bond.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStack flat, not on edge:\u003c\/strong\u003e Storing 50 mm boards on edge can cause bowing over time — flat storage preserves the rebated geometry.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"certifications-and-compliance-atlas-fundament-50mm\"\u003eCertifications \u0026amp; Compliance — Atlas Fundament 50 mm\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament boards are manufactured to recognised European foundation insulation standards. Reaction to fire is classified under EN 13501-1, and the declared thermal conductivity (λ 0.038 W\/mK) appears on the manufacturer's current Declaration of Performance. For projects requiring specific compressive strength values, water absorption test results, or Approved Document L 2021 calculation inputs (current at time of writing), request the latest DoP at order — exact certified values can vary between production batches and the current Atlas Fundament datasheet is the authoritative reference.\u003c\/p\u003e\n\u003ch2 id=\"is-atlas-fundament-50mm-right-for-your-project\"\u003eIs Atlas Fundament 50 mm Right for Your Project?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose this thickness if\u003c\/strong\u003e your project needs foundation insulation that contributes meaningfully to U-value calculations without requiring deep backfill — typically floor insulation under screed, shallow foundation wraps on lighter domestic builds, or new-build plinth zones where the facade can plan around 50 mm of projection.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWorking with restricted build-up depth?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-30mm-1-board-0-038w\"\u003eAtlas Fundament 30 mm\u003c\/a\u003e handles screed underlay and thin plinth retrofits where 50 mm would clash with adjacent EPS courses.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTargeting modern U-value standards?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e at R 2.11 m²K\/W is the standard specification for foundation and basement walls on Part L 2021 projects.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDetailing the plinth-to-facade transition?\u003c\/strong\u003e The \u003ca href=\"\/blogs\/news\/thermal-bridges-plinth-insulation-mould-prevention\"\u003eplinth thermal-bridge guide\u003c\/a\u003e walks through the 100 mm overlap detail that keeps the DPC line condensation-free.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"what-to-order-next-pack-sizes-lead-times-compatible-components\"\u003eWhat to Order Next — Pack Sizes, Lead Times, Compatible Components\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 50 mm is supplied as a single board (0.75 m² coverage). For project calculations, allow 1.33 boards per m² plus 5–10% cutting waste. To complete the foundation build-up, order Ceresit CT84 XPS Foam for bonding and a fixing pattern of 6–8 plugs per m² above grade for wind-uplift resistance.\u003c\/p\u003e\n\u003ch2 id=\"faq-atlas-fundament-50mm-coverage-compatibility-installation\"\u003eFAQ — Atlas Fundament 50 mm Coverage, Compatibility, Installation\u003c\/h2\u003e\n\u003ch3 id=\"how-many-50mm-atlas-fundament-boards-do-i-need-per-square-metre\"\u003eHow many 50 mm Atlas Fundament boards do I need per square metre?\u003c\/h3\u003e\n\u003cp\u003eEach board covers 0.75 m² (600 × 1250 mm), so 1.33 boards per m² is the base figure. For typical foundation-wrap and floor-insulation runs, add 5–10% cutting waste for corners, openings, and rebated overlaps, then round up to the nearest full board.\u003c\/p\u003e\n\u003ch3 id=\"is-50mm-enough-for-a-domestic-foundation-wrap\"\u003eIs 50 mm enough for a domestic foundation wrap?\u003c\/h3\u003e\n\u003cp\u003eFor lighter domestic builds and retrofit projects where the thermal target is modest, 50 mm delivers a workable R 1.32 m²K\/W that contributes meaningfully to overall foundation U-values. For new-build projects aiming at current Part L 2021 targets (current at time of writing), 80 mm to 100 mm is the more common specification — confirm the required thickness through a project-specific U-value calculation.\u003c\/p\u003e\n\u003ch3 id=\"can-i-use-50mm-atlas-fundament-under-a-domestic-screed\"\u003eCan I use 50 mm Atlas Fundament under a domestic screed?\u003c\/h3\u003e\n\u003cp\u003eYes — the closed-cell structure tolerates the wet trade without water uptake, and the foundation-grade compressive strength supports standard domestic floor loads without additional reinforcement. Lay the boards horizontally over a level slab, butt the rebated edges tight, then pour screed directly above to the specified depth.\u003c\/p\u003e\n\u003ch3 id=\"what-adhesive-bonds-atlas-fundament-50mm-to-a-foundation-wall\"\u003eWhat adhesive bonds Atlas Fundament 50 mm to a foundation wall?\u003c\/h3\u003e\n\u003cp\u003eA specialist polyurethane adhesive such as Ceresit CT84 XPS Foam is the standard route — it cures fast in cool, damp UK ground-level conditions and bonds reliably to closed-cell board surfaces. Apply in continuous beads around the perimeter plus a central bead, brush dust from the rebated edge before placement, and press firmly to spread the foam across the full bonding face.\u003c\/p\u003e\n\u003ch3 id=\"does-50mm-need-mechanical-fixings-as-well-as-adhesive\"\u003eDoes 50 mm need mechanical fixings as well as adhesive?\u003c\/h3\u003e\n\u003cp\u003eBelow ground level, backfill provides permanent mechanical restraint and the polyurethane foam adhesive alone is typically sufficient. Above grade on exposed plinth runs, add mechanical fixings at 6–8 plugs per m² per the project's fixing layout to resist wind uplift — the 50 mm board catches more wind load than thinner variants, so this is the depth at which mechanical fixings become standard practice on exposed elevations.\u003c\/p\u003e\n\u003ch3 id=\"how-does-50mm-compare-thermally-to-80mm-atlas-fundament\"\u003eHow does 50 mm compare thermally to 80 mm Atlas Fundament?\u003c\/h3\u003e\n\u003cp\u003eAt the same declared λ of 0.038 W\/mK, the 50 mm board delivers R 1.32 m²K\/W and the \u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003e80 mm Atlas Fundament\u003c\/a\u003e delivers R 2.11 — a 60% uplift in thermal resistance for an extra 30 mm of depth. Where the build-up can accommodate 80 mm and the project targets current Part L thresholds, the 80 mm version is typically the stronger specification.\u003c\/p\u003e","brand":"Renders World","offers":[{"title":"Default Title","offer_id":56400715448695,"sku":null,"price":6.5,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0973\/1375\/1415\/files\/aqua-poliester-eps-board_3f58f25e-5612-408d-9ac1-0b81c5a01d06.jpg?v=1767042905"},{"product_id":"eps-foundation-90mm-1-board-0-038w","title":"EPS FOUNDATION 90mm (1 BOARD) 0.038W","description":"\u003cp\u003eWithin the \u003ca href=\"\/collections\/xps-insulationboards\"\u003eXPS insulation boards\u003c\/a\u003e range, Atlas Fundament 90 mm is the precision thickness for below-DPC plinth zones where the foundation insulation has to align flush with the graphite EPS course on the facade above. The board delivers a thermal conductivity of \u003cstrong\u003eλ 0.038 W\/mK\u003c\/strong\u003e in a closed-cell foundation-grade structure, measuring 600 × 1250 mm with rebated edges and covering 0.75 m² per board.\u003c\/p\u003e\n\u003ch2 id=\"what-atlas-fundament-90mm-does-in-a-uk-ewi-system\"\u003eWhat Atlas Fundament 90 mm Does in a UK EWI System\u003c\/h2\u003e\n\u003cp\u003ePlinth-to-facade alignment is the deciding factor on most EWI retrofits, and Atlas Fundament 90 mm exists to solve it. At R 2.37 m²K\/W and λ 0.038 W\/mK in a closed-cell foundation board, the 90 mm depth matches the most common graphite EPS facade thickness above DPC — letting the plinth zone read as a continuous insulation plane with the elevation above, with no step at the damp-proof course line and no render-thickness compensation to engineer around.\u003c\/p\u003e\n\u003cp\u003eEach board measures 600 × 1250 mm with rebated edges that lock together to form a continuous insulation plane without thermal bridging at the joints, so the moisture-resistant layer reads as a single membrane from one course to the next and meets the facade insulation flush at DPC.\u003c\/p\u003e\n\u003ch2 id=\"why-specifiers-choose-atlas-fundament-90mm-for-uk-walls\"\u003eWhy Specifiers Choose Atlas Fundament 90 mm for UK Walls\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlush plinth-to-facade alignment:\u003c\/strong\u003e 90 mm matches the common 90 mm graphite EPS facade thickness above DPC, eliminating the step that 80 mm or 100 mm boards would force into the render finish line.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStrong below-DPC thermal performance:\u003c\/strong\u003e R 2.37 m²K\/W sits between standard Part L specification and deep-wrap territory, delivering meaningful thermal continuity through the plinth zone.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClosed-cell moisture protection:\u003c\/strong\u003e Permanent resistance to ground moisture and hydrostatic pressure keeps thermal performance constant for the life of the foundation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRebated edges for joint integrity:\u003c\/strong\u003e Tight overlapping joints reduce the cold-bridge risk that flat-edge boards leave at every horizontal course.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFreeze-thaw stable:\u003c\/strong\u003e Holds full R-value through repeated UK winter cycles in exposed plinth and below-grade positions.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"thermal-specifications-atlas-fundament-90mm\"\u003eThermal Specifications — Atlas Fundament 90 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal conductivity (λ)\u003c\/td\u003e\n\u003ctd\u003e0.038 W\/mK\u003c\/td\u003e\n\u003ctd\u003eDeclared value for foundation board\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThickness\u003c\/td\u003e\n\u003ctd\u003e90 mm\u003c\/td\u003e\n\u003ctd\u003ePlinth-alignment specification\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal resistance (R)\u003c\/td\u003e\n\u003ctd\u003e2.37 m²K\/W\u003c\/td\u003e\n\u003ctd\u003eAt declared λ × thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReaction to fire\u003c\/td\u003e\n\u003ctd\u003ePer EN 13501-1\u003c\/td\u003e\n\u003ctd\u003eConfirm via current DoP at order\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater absorption\u003c\/td\u003e\n\u003ctd\u003eLow (closed-cell)\u003c\/td\u003e\n\u003ctd\u003eSuitable for permanent ground contact\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"physical-specifications-atlas-fundament-90mm\"\u003ePhysical Specifications — Atlas Fundament 90 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoard dimensions\u003c\/td\u003e\n\u003ctd\u003e600 × 1250 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoverage per board\u003c\/td\u003e\n\u003ctd\u003e0.75 m²\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEdge profile\u003c\/td\u003e\n\u003ctd\u003eRebated (lap joint)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompressive strength\u003c\/td\u003e\n\u003ctd\u003eFoundation-grade (confirm via TDS at order)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoards per m²\u003c\/td\u003e\n\u003ctd\u003e1.33 (add 5–10% cutting waste)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"where-atlas-fundament-90mm-performs-best-wall-types-and-build-up\"\u003eWhere Atlas Fundament 90 mm Performs Best — Wall Types \u0026amp; Build-Up\u003c\/h2\u003e\n\u003cp\u003eThe 90 mm thickness is purpose-specified for one detailing decision: how the plinth meets the facade. On EWI retrofits and new-builds where the elevation above DPC will be insulated with 90 mm graphite EPS — the most common facade thickness for UK domestic projects — the foundation board needs to land on the same plane. The 90 mm Atlas Fundament delivers that flush transition without forcing the render line to step or the basecoat to compensate at the DPC junction.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlinth zones with 90 mm graphite EPS above DPC:\u003c\/strong\u003e Position from ground level up to the damp-proof course where the facade above is being insulated with matching-thickness graphite EPS. The plinth-to-facade joint reads as one continuous plane.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBelow-DPC zones on solid-wall retrofits:\u003c\/strong\u003e Use on Victorian and Edwardian retrofit projects where the facade EWI build-up has been set at 90 mm to balance thermal target against window-reveal geometry.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFoundation wraps targeting above-standard U-values:\u003c\/strong\u003e Where the project pushes past standard Part L thresholds but stops short of Passive-leaning depths, 90 mm sits in the engineered middle ground.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBasement perimeter on deeper retrofits:\u003c\/strong\u003e Apply across basement and cellar perimeters where the project specifies a thermal target above the typical 80 mm baseline.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"how-atlas-fundament-90mm-fits-into-a-full-ewi-system\"\u003eHow Atlas Fundament 90 mm Fits Into a Full EWI System\u003c\/h2\u003e\n\u003cp\u003eIn a full external wall insulation build-up, Atlas Fundament 90 mm handles the plinth and below-DPC foundation zone, while the main facade above is finished with matching-thickness \u003ca href=\"\/collections\/eps-insulation-boards\"\u003egraphite EPS boards\u003c\/a\u003e bonded with adhesive-and-basecoat and finished with mesh-reinforced render. The alignment story is the system story: when the plinth XPS lands on the same plane as the facade EPS, the basecoat and mesh wrap the transition without thickness compensation, and the render reads as one continuous finish from ground level to eaves.\u003c\/p\u003e\n\u003cp\u003eBond the 90 mm board with a specialist polyurethane adhesive such as \u003ca href=\"\/products\/ceresit-ct84-xps-foam-850ml\"\u003eCeresit CT84 XPS Foam\u003c\/a\u003e, which cures fast in the cool, damp conditions typical of UK ground-level work. Above ground — particularly on exposed plinth runs — add mechanical fixings from the \u003ca href=\"\/collections\/fixing-accesories\"\u003eEWI fixing accessories range\u003c\/a\u003e at 6–8 plugs per m², stepping up to 8 plugs per m² on corners and edges.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-90mm-compares-to-sibling-foundation-boards\"\u003eHow Atlas Fundament 90 mm Compares to Sibling Foundation Boards\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBoard\u003c\/th\u003e\n\u003cth\u003eThickness\u003c\/th\u003e\n\u003cth\u003eR-Value (m²K\/W)\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-50mm-1-board-0-038w\"\u003eAtlas Fundament 50 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003ctd\u003e1.32\u003c\/td\u003e\n\u003ctd\u003eFloor insulation, shallow foundation wrap\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e80 mm\u003c\/td\u003e\n\u003ctd\u003e2.11\u003c\/td\u003e\n\u003ctd\u003eStandard foundation, basement walls, Part L target\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAtlas Fundament 90 mm\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e90 mm\u003c\/td\u003e\n\u003ctd\u003e2.37\u003c\/td\u003e\n\u003ctd\u003eBelow-DPC plinth flush with 90 mm facade EPS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003eAtlas Fundament 100 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e100 mm\u003c\/td\u003e\n\u003ctd\u003e2.63\u003c\/td\u003e\n\u003ctd\u003eDeep foundation wrap, highest thermal target\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eFor projects weighing closed-cell foundation insulation against graphite EPS for the main facade, the \u003ca href=\"\/blogs\/news\/xps-vs-eps-insulation-uk\"\u003eXPS vs EPS comparison guide\u003c\/a\u003e walks through where each material wins across the build-up.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-90mm-performs-in-uk-weather\"\u003eHow Atlas Fundament 90 mm Performs in UK Weather — Moisture, Frost, Wind Loads\u003c\/h2\u003e\n\u003cp\u003eThe closed-cell structure keeps long-term water absorption at near-zero, so freeze-thaw cycling across a typical UK winter does not progressively reduce R-value the way it can on open-cell boards exposed to ground moisture. In splash-zone positions at the plinth, the 90 mm board holds its thermal performance through saturation, drying, and re-saturation cycles for decades — critical for the zone where driven rain, ground splash, and capillary moisture combine throughout a UK winter.\u003c\/p\u003e\n\u003cp\u003eWind-load exposure is a meaningful factor above grade. The 90 mm face area catches more uplift than the 80 mm board, so the mechanical fixing layout should be set to the project-specific pattern rather than a generic field rate — typical layouts run 6 plugs per m² across the field and step up to 8 plugs per m² on corners and edges, with additional fixings around openings.\u003c\/p\u003e\n\u003ch2 id=\"handling-and-storage-on-site\"\u003eHandling \u0026amp; Storage on Site\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eKeep dry and shaded:\u003c\/strong\u003e Stack boards flat on a clean, level surface. Cover with sheeting if outdoor storage exceeds a few weeks — prolonged UV softens the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eScore, don't snap:\u003c\/strong\u003e Cut with a fine-tooth saw or sharp blade rather than snapping the rebated edge. A clean cut keeps the bonding face true and protects the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrush the rebate before adhesive:\u003c\/strong\u003e Dust on the lap joint breaks the foam adhesive seal; a quick brush gives a full-face bond.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSet the DPC course line first:\u003c\/strong\u003e Mark the DPC line and the facade-EPS course position before fitting the first 90 mm board. Working from a chalked datum keeps the plinth-to-facade alignment true across the whole elevation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"certifications-and-compliance-atlas-fundament-90mm\"\u003eCertifications \u0026amp; Compliance — Atlas Fundament 90 mm\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament boards are manufactured to recognised European foundation insulation standards. Reaction to fire is classified under EN 13501-1, and the declared thermal conductivity (λ 0.038 W\/mK) appears on the manufacturer's current Declaration of Performance. For projects requiring specific compressive strength values, water absorption test results, or Approved Document L 2021 calculation inputs (current at time of writing), request the latest DoP at order — exact certified values can vary between production batches and the current Atlas Fundament datasheet is the authoritative reference for compliance submissions.\u003c\/p\u003e\n\u003ch2 id=\"is-atlas-fundament-90mm-right-for-your-project\"\u003eIs Atlas Fundament 90 mm Right for Your Project?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose this thickness if\u003c\/strong\u003e your project plans a 90 mm graphite EPS facade above DPC — the foundation board matches the facade plane and lets the basecoat, mesh, and render wrap the DPC transition without thickness compensation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWorking at standard Part L depth?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e at R 2.11 m²K\/W is the volume-runner where the facade EPS sits at 80 mm or where standard foundation U-value targets apply.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePushing past current Part L thresholds?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003eAtlas Fundament 100 mm\u003c\/a\u003e at R 2.63 m²K\/W is the specification for Passive-leaning new-builds and deep retrofit projects.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDetailing the plinth-to-facade transition?\u003c\/strong\u003e The \u003ca href=\"\/blogs\/news\/thermal-bridges-plinth-insulation-mould-prevention\"\u003eplinth thermal-bridge guide\u003c\/a\u003e walks through the overlap detail that keeps the DPC line condensation-free regardless of the chosen thickness.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"what-to-order-next-pack-sizes-lead-times-compatible-components\"\u003eWhat to Order Next — Pack Sizes, Lead Times, Compatible Components\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 90 mm is supplied as a single board (0.75 m² coverage). For project calculations, allow 1.33 boards per m² plus 5–10% cutting waste — the alignment-driven nature of 90 mm specifications means cutting waste tends to land at the lower end of the range when the plinth is set out properly. To complete the foundation build-up, order Ceresit CT84 XPS Foam for bonding and a fixing pattern of 6–8 plugs per m² above grade, stepping up to 8 plugs per m² on exposed corners and edges.\u003c\/p\u003e\n\u003ch2 id=\"faq-atlas-fundament-90mm-coverage-compatibility-installation\"\u003eFAQ — Atlas Fundament 90 mm Coverage, Compatibility, Installation\u003c\/h2\u003e\n\u003ch3 id=\"how-many-90mm-atlas-fundament-boards-do-i-need-per-square-metre\"\u003eHow many 90 mm Atlas Fundament boards do I need per square metre?\u003c\/h3\u003e\n\u003cp\u003eEach board covers 0.75 m² (600 × 1250 mm), so 1.33 boards per m² is the base figure. For plinth runs where the board height is set against the DPC line and the facade-EPS course position, add 5–10% cutting waste for corners and openings, then round up to the nearest full board.\u003c\/p\u003e\n\u003ch3 id=\"why-90mm-rather-than-80-or-100mm\"\u003eWhy 90 mm rather than 80 or 100 mm?\u003c\/h3\u003e\n\u003cp\u003eThe 90 mm thickness exists for one reason: alignment with the 90 mm graphite EPS facade thickness most commonly specified above DPC on UK domestic EWI projects. When the plinth board and the facade board land on the same plane, the basecoat and mesh wrap the DPC transition without thickness compensation, and the render finish reads as one continuous plane from ground level to eaves. Where the facade EPS sits at 80 mm or 100 mm, match the foundation board to that thickness instead.\u003c\/p\u003e\n\u003ch3 id=\"what-adhesive-bonds-atlas-fundament-90mm-to-a-foundation-wall\"\u003eWhat adhesive bonds Atlas Fundament 90 mm to a foundation wall?\u003c\/h3\u003e\n\u003cp\u003eA specialist polyurethane adhesive such as Ceresit CT84 XPS Foam is the standard route — it cures fast in cool, damp UK ground-level conditions and bonds reliably to closed-cell board surfaces. Apply in continuous beads around the perimeter plus a central bead, brush dust from the rebated edge before placement, and press firmly to spread the foam across the full bonding face.\u003c\/p\u003e\n\u003ch3 id=\"does-90mm-need-mechanical-fixings-above-grade\"\u003eDoes 90 mm need mechanical fixings above grade?\u003c\/h3\u003e\n\u003cp\u003eAbove ground level on plinth zones, yes — the 90 mm board's face area catches enough wind uplift that mechanical fixings are standard practice. Typical layouts run 6 plugs per m² across the field and 8 plugs per m² on exposed corners and edges, with additional fixings around openings. Below ground level, backfill provides permanent mechanical restraint and the polyurethane foam adhesive alone is typically sufficient.\u003c\/p\u003e\n\u003ch3 id=\"can-i-use-90mm-atlas-fundament-on-a-facade-above-dpc\"\u003eCan I use 90 mm Atlas Fundament on a facade above DPC?\u003c\/h3\u003e\n\u003cp\u003eThe closed-cell structure limits vapour permeability, so the main facade above DPC typically benefits from graphite EPS or mineral wool rather than foundation-grade board — vapour-permeable insulation lets moisture migrate outward through the render system. The 90 mm Atlas Fundament earns its place at the plinth and below-DPC zones where its moisture resistance is the deciding factor, with matching-thickness graphite EPS continuing the build-up above DPC.\u003c\/p\u003e\n\u003ch3 id=\"how-do-i-detail-the-plinth-to-facade-transition-with-90mm\"\u003eHow do I detail the plinth-to-facade transition with 90 mm?\u003c\/h3\u003e\n\u003cp\u003eMark the DPC line and the facade-EPS course position as a single datum, then fit the 90 mm Atlas Fundament so the top of the board sits flush with the bottom edge of the first facade-EPS course above DPC. With the planes aligned, wrap the joint with mesh and basecoat as a continuous reinforced layer — the \u003ca href=\"\/blogs\/news\/thermal-bridges-plinth-insulation-mould-prevention\"\u003eplinth thermal-bridge guide\u003c\/a\u003e walks through the recommended overlap dimensions for the basecoat reinforcement.\u003c\/p\u003e","brand":"Renders World","offers":[{"title":"Default Title","offer_id":56400715645303,"sku":null,"price":9.5,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0973\/1375\/1415\/files\/aqua-poliester-eps-board_5bb61e9f-b941-4117-9a18-23c9d2f8a21a.jpg?v=1767042908"},{"product_id":"eps-foundation-100mm-1-board-0-038w","title":"EPS FOUNDATION 100mm (1 BOARD) 0.038W","description":"\u003cp\u003eWithin the \u003ca href=\"\/collections\/xps-insulationboards\"\u003eXPS insulation boards\u003c\/a\u003e range, Atlas Fundament 100 mm is the deepest foundation board in the series — engineered for Passive-leaning new-builds, deep retrofit projects, and any below-DPC zone pushing past standard Part L thermal targets. The board delivers a thermal conductivity of \u003cstrong\u003eλ 0.038 W\/mK\u003c\/strong\u003e in a closed-cell foundation-grade structure, measuring 600 × 1250 mm with rebated edges and covering 0.75 m² per board at R 2.63 m²K\/W.\u003c\/p\u003e\n\u003ch2 id=\"what-atlas-fundament-100mm-does-in-a-uk-ewi-system\"\u003eWhat Atlas Fundament 100 mm Does in a UK EWI System\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 100 mm is the deepest XPS foundation board in the range, designed for the projects pushing past standard Part L 2021 thresholds (current at time of writing) toward Future Homes Standard 2026 trajectory thermal targets. At R 2.63 m²K\/W and λ 0.038 W\/mK in a closed-cell foundation board, the 100 mm depth handles deep foundation wraps, basement perimeters on high-performance new-builds, and full-depth plinth specifications on retrofit projects targeting U-values below the typical 0.18 W\/m²K threshold.\u003c\/p\u003e\n\u003cp\u003eEach board measures 600 × 1250 mm with rebated edges that lock together to form a continuous insulation plane without thermal bridging at the joints — so the moisture-resistant layer reads as a single membrane from one course to the next, regardless of the deeper face profile.\u003c\/p\u003e\n\u003ch2 id=\"why-specifiers-choose-atlas-fundament-100mm-for-uk-walls\"\u003eWhy Specifiers Choose Atlas Fundament 100 mm for UK Walls\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeepest thermal performance in the range:\u003c\/strong\u003e R 2.63 m²K\/W is the maximum from the Atlas Fundament series — the specification for projects targeting U-values below standard Part L thresholds.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClosed-cell moisture protection:\u003c\/strong\u003e Permanent resistance to ground moisture and hydrostatic pressure keeps thermal performance constant for the life of the foundation up to 2 m below grade.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRebated edges for joint integrity:\u003c\/strong\u003e Tight overlapping joints reduce the cold-bridge risk that flat-edge boards leave at every horizontal course — particularly important at this depth where any thermal bridge proportionally erodes the high R-value.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFreeze-thaw stable:\u003c\/strong\u003e Holds full R-value through repeated UK winter cycles in exposed plinth and below-grade positions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFuture Homes Standard trajectory:\u003c\/strong\u003e Sits at the depth most high-performance new-builds gravitate toward as Part L tightens through the Future Homes Standard 2026 roadmap.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"thermal-specifications-atlas-fundament-100mm\"\u003eThermal Specifications — Atlas Fundament 100 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal conductivity (λ)\u003c\/td\u003e\n\u003ctd\u003e0.038 W\/mK\u003c\/td\u003e\n\u003ctd\u003eDeclared value for foundation board\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThickness\u003c\/td\u003e\n\u003ctd\u003e100 mm\u003c\/td\u003e\n\u003ctd\u003eDeepest Atlas Fundament thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal resistance (R)\u003c\/td\u003e\n\u003ctd\u003e2.63 m²K\/W\u003c\/td\u003e\n\u003ctd\u003eAt declared λ × thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReaction to fire\u003c\/td\u003e\n\u003ctd\u003ePer EN 13501-1\u003c\/td\u003e\n\u003ctd\u003eConfirm via current DoP at order\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater absorption\u003c\/td\u003e\n\u003ctd\u003eLow (closed-cell)\u003c\/td\u003e\n\u003ctd\u003eSuitable for permanent ground contact\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"physical-specifications-atlas-fundament-100mm\"\u003ePhysical Specifications — Atlas Fundament 100 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoard dimensions\u003c\/td\u003e\n\u003ctd\u003e600 × 1250 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoverage per board\u003c\/td\u003e\n\u003ctd\u003e0.75 m²\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEdge profile\u003c\/td\u003e\n\u003ctd\u003eRebated (lap joint)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompressive strength\u003c\/td\u003e\n\u003ctd\u003eFoundation-grade (confirm via TDS at order)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoards per m²\u003c\/td\u003e\n\u003ctd\u003e1.33 (add 5–10% cutting waste)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"where-atlas-fundament-100mm-performs-best-wall-types-and-build-up\"\u003eWhere Atlas Fundament 100 mm Performs Best — Wall Types \u0026amp; Build-Up\u003c\/h2\u003e\n\u003cp\u003eThe 100 mm thickness is where Atlas Fundament earns its place on projects pushing past the standard Part L baseline. The depth is engineered for the high-performance end of UK domestic specification — new-builds aiming at the \u003ca href=\"\/blogs\/news\/standard-future-homes-2026-uk\"\u003eFuture Homes Standard 2026 trajectory\u003c\/a\u003e, deep retrofit projects on solid-wall stock targeting modern U-value standards, and basement perimeters where the thermal target sits noticeably below current minimums.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeep foundation wraps on Passive-leaning new-builds:\u003c\/strong\u003e Apply vertically against the external face of the foundation wall on projects targeting U-values below the typical 0.18 W\/m²K threshold.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBasement perimeter on high-performance projects:\u003c\/strong\u003e Use across basement and cellar perimeters up to 2 m below ground level where the thermal target requires the deepest available foundation insulation.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDeep plinth zones on solid-wall retrofits:\u003c\/strong\u003e Position from ground level up to the DPC line on projects insulating solid-wall stock with deeper facade EPS above — typically 100 mm or thicker.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHeated cellar conversions:\u003c\/strong\u003e Lay horizontally over the slab in heated basement and cellar conversions where the floor needs to perform thermally as part of a heated envelope rather than a cold buffer zone.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"how-atlas-fundament-100mm-fits-into-a-full-ewi-system\"\u003eHow Atlas Fundament 100 mm Fits Into a Full EWI System\u003c\/h2\u003e\n\u003cp\u003eIn a full external wall insulation build-up, Atlas Fundament 100 mm handles the plinth and below-DPC foundation zone, while the main facade above is finished with matching-depth \u003ca href=\"\/collections\/eps-insulation-boards\"\u003egraphite EPS boards\u003c\/a\u003e bonded with adhesive-and-basecoat and finished with mesh-reinforced render. At 100 mm both above and below DPC, the plinth-to-facade joint reads as one continuous insulation plane — and the deeper system gives the project a stronger position against tightening Part L thresholds without further upgrade work.\u003c\/p\u003e\n\u003cp\u003eBond the 100 mm board with a specialist polyurethane adhesive such as \u003ca href=\"\/products\/ceresit-ct84-xps-foam-850ml\"\u003eCeresit CT84 XPS Foam\u003c\/a\u003e, which cures fast in the cool, damp conditions typical of UK ground-level work. Above ground — particularly on exposed plinth runs — add mechanical fixings from the \u003ca href=\"\/collections\/fixing-accesories\"\u003eEWI fixing accessories range\u003c\/a\u003e at 6–8 plugs per m², stepping up to 8 plugs per m² on corners and edges. At 100 mm depth, the fixings need a longer plug length than 80 mm or 90 mm builds — confirm plug length against the project fixing schedule before ordering.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-100mm-compares-to-sibling-foundation-boards\"\u003eHow Atlas Fundament 100 mm Compares to Sibling Foundation Boards\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBoard\u003c\/th\u003e\n\u003cth\u003eThickness\u003c\/th\u003e\n\u003cth\u003eR-Value (m²K\/W)\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-30mm-1-board-0-038w\"\u003eAtlas Fundament 30 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e30 mm\u003c\/td\u003e\n\u003ctd\u003e0.79\u003c\/td\u003e\n\u003ctd\u003eScreed underlay, thin plinth, reveal zones\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-50mm-1-board-0-038w\"\u003eAtlas Fundament 50 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003ctd\u003e1.32\u003c\/td\u003e\n\u003ctd\u003eFloor insulation, shallow foundation wrap\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e80 mm\u003c\/td\u003e\n\u003ctd\u003e2.11\u003c\/td\u003e\n\u003ctd\u003eStandard foundation, basement walls, Part L target\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-90mm-1-board-0-038w\"\u003eAtlas Fundament 90 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e90 mm\u003c\/td\u003e\n\u003ctd\u003e2.37\u003c\/td\u003e\n\u003ctd\u003eBelow-DPC plinth flush with 90 mm facade EPS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAtlas Fundament 100 mm\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e100 mm\u003c\/td\u003e\n\u003ctd\u003e2.63\u003c\/td\u003e\n\u003ctd\u003eDeep foundation wrap, Passive-leaning, Future Homes trajectory\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eFor projects weighing closed-cell foundation insulation against graphite EPS for the main facade, the \u003ca href=\"\/blogs\/news\/xps-vs-eps-insulation-uk\"\u003eXPS vs EPS comparison guide\u003c\/a\u003e walks through where each material wins across the build-up.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-100mm-performs-in-uk-weather\"\u003eHow Atlas Fundament 100 mm Performs in UK Weather — Moisture, Frost, Wind Loads\u003c\/h2\u003e\n\u003cp\u003eThe closed-cell structure keeps long-term water absorption at near-zero, so freeze-thaw cycling across a typical UK winter does not progressively reduce R-value the way it can on open-cell boards exposed to ground moisture. In splash-zone positions at the plinth, the 100 mm board holds its thermal performance through saturation, drying, and re-saturation cycles for decades — and the deeper face protects the substrate from temperature swings that thinner boards transmit more readily.\u003c\/p\u003e\n\u003cp\u003eWind-load exposure is the most demanding of any thickness in the range. The 100 mm face area catches significantly more uplift than 80 mm or 90 mm boards do, so the mechanical fixing layout should follow the project-specific pattern — typically 6 plugs per m² across the field and 8 plugs per m² on corners and edges, with additional fixings around openings. On exposed coastal or high-altitude sites, the fixing schedule may require a denser pattern still.\u003c\/p\u003e\n\u003ch2 id=\"handling-and-storage-on-site\"\u003eHandling \u0026amp; Storage on Site\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eKeep dry and shaded:\u003c\/strong\u003e Stack boards flat on a clean, level surface. Cover with sheeting if outdoor storage exceeds a few weeks — prolonged UV softens the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eScore, don't snap:\u003c\/strong\u003e Cut with a fine-tooth saw or sharp blade rather than snapping the rebated edge. A clean cut keeps the bonding face true and protects the closed-cell surface — especially important at 100 mm where any compromised edge magnifies the cold-bridge risk.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrush the rebate before adhesive:\u003c\/strong\u003e Dust on the lap joint breaks the foam adhesive seal; a quick brush gives a full-face bond.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConfirm plug length before ordering fixings:\u003c\/strong\u003e The 100 mm board needs a longer mechanical fixing than 80 mm or 90 mm builds. Order plug length to suit the board thickness plus the substrate-embed depth specified in the project fixing schedule.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"certifications-and-compliance-atlas-fundament-100mm\"\u003eCertifications \u0026amp; Compliance — Atlas Fundament 100 mm\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament boards are manufactured to recognised European foundation insulation standards. Reaction to fire is classified under EN 13501-1, and the declared thermal conductivity (λ 0.038 W\/mK) appears on the manufacturer's current Declaration of Performance. For projects requiring specific compressive strength values, water absorption test results, or Approved Document L 2021 calculation inputs (current at time of writing), request the latest DoP at order — exact certified values can vary between production batches and the current Atlas Fundament datasheet is the authoritative reference for compliance submissions, particularly on projects pursuing above-standard thermal targets.\u003c\/p\u003e\n\u003ch2 id=\"is-atlas-fundament-100mm-right-for-your-project\"\u003eIs Atlas Fundament 100 mm Right for Your Project?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose this thickness if\u003c\/strong\u003e your project targets U-values below the standard Part L baseline — Passive-leaning new-builds, deep retrofit on solid-wall stock, or any specification on the Future Homes Standard 2026 trajectory where the foundation insulation needs to match an above-standard facade build-up.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWorking at standard Part L depth?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-80mm-1-board-0-038w\"\u003eAtlas Fundament 80 mm\u003c\/a\u003e at R 2.11 m²K\/W is the volume-runner for most domestic new-builds and EWI retrofits.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNeed plinth-to-facade alignment with a 90 mm EPS elevation?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-90mm-1-board-0-038w\"\u003eAtlas Fundament 90 mm\u003c\/a\u003e matches the most common facade EPS thickness above DPC for a flush plane.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDetailing the plinth-to-facade transition?\u003c\/strong\u003e The \u003ca href=\"\/blogs\/news\/thermal-bridges-plinth-insulation-mould-prevention\"\u003eplinth thermal-bridge guide\u003c\/a\u003e walks through the overlap detail that keeps the DPC line condensation-free regardless of the chosen thickness.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"what-to-order-next-pack-sizes-lead-times-compatible-components\"\u003eWhat to Order Next — Pack Sizes, Lead Times, Compatible Components\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 100 mm is supplied as a single board (0.75 m² coverage). For project calculations, allow 1.33 boards per m² plus 5–10% cutting waste. To complete the foundation build-up, order Ceresit CT84 XPS Foam for bonding and a fixing pattern of 6–8 plugs per m² above grade, stepping up to 8 plugs per m² on exposed corners and edges — with plug length set to match the 100 mm board depth plus the project's substrate-embed requirement.\u003c\/p\u003e\n\u003ch2 id=\"faq-atlas-fundament-100mm-coverage-compatibility-installation\"\u003eFAQ — Atlas Fundament 100 mm Coverage, Compatibility, Installation\u003c\/h2\u003e\n\u003ch3 id=\"how-many-100mm-atlas-fundament-boards-do-i-need-per-square-metre\"\u003eHow many 100 mm Atlas Fundament boards do I need per square metre?\u003c\/h3\u003e\n\u003cp\u003eEach board covers 0.75 m² (600 × 1250 mm), so 1.33 boards per m² is the base figure. For deep foundation wraps and full basement perimeters, add 5–10% cutting waste for corners, openings, and rebated overlaps, then round up to the nearest full board.\u003c\/p\u003e\n\u003ch3 id=\"when-is-100mm-the-right-foundation-thickness\"\u003eWhen is 100 mm the right foundation thickness?\u003c\/h3\u003e\n\u003cp\u003eThe 100 mm thickness is specified where the project targets U-values below the standard Part L baseline — Passive-leaning new-builds, deep retrofit on solid-wall stock, projects positioned for the Future Homes Standard 2026 trajectory, or heated cellar conversions where the floor and perimeter need to perform thermally as part of a heated envelope. For projects sitting at standard Part L thresholds, 80 mm is typically the more cost-effective specification.\u003c\/p\u003e\n\u003ch3 id=\"what-adhesive-bonds-atlas-fundament-100mm-to-a-foundation-wall\"\u003eWhat adhesive bonds Atlas Fundament 100 mm to a foundation wall?\u003c\/h3\u003e\n\u003cp\u003eA specialist polyurethane adhesive such as Ceresit CT84 XPS Foam is the standard route — it cures fast in cool, damp UK ground-level conditions and bonds reliably to closed-cell board surfaces. Apply in continuous beads around the perimeter plus a central bead, brush dust from the rebated edge before placement, and press firmly to spread the foam across the full bonding face.\u003c\/p\u003e\n\u003ch3 id=\"what-plug-length-do-i-need-for-100mm-mechanical-fixings\"\u003eWhat plug length do I need for 100 mm mechanical fixings?\u003c\/h3\u003e\n\u003cp\u003ePlug length must cover the 100 mm board depth plus the substrate-embed depth specified in the project fixing schedule — typically 50–60 mm of embed into the substrate, giving an overall plug length around 150–160 mm for standard masonry conditions. Confirm the exact figure against the project schedule before ordering, since substrate type and condition affect the embed depth requirement.\u003c\/p\u003e\n\u003ch3 id=\"can-i-use-100mm-atlas-fundament-on-a-facade-above-dpc\"\u003eCan I use 100 mm Atlas Fundament on a facade above DPC?\u003c\/h3\u003e\n\u003cp\u003eThe closed-cell structure limits vapour permeability, so the main facade above DPC typically benefits from graphite EPS or mineral wool rather than foundation-grade board — vapour-permeable insulation lets moisture migrate outward through the render system. The 100 mm Atlas Fundament earns its place at the plinth and below-DPC zones where its moisture resistance is the deciding factor, with matching-depth graphite EPS continuing the build-up above DPC for a flush 100 mm plane top to bottom.\u003c\/p\u003e\n\u003ch3 id=\"how-does-100mm-compare-to-90mm-atlas-fundament\"\u003eHow does 100 mm compare to 90 mm Atlas Fundament?\u003c\/h3\u003e\n\u003cp\u003eAt the same declared λ of 0.038 W\/mK, the \u003ca href=\"\/products\/eps-foundation-90mm-1-board-0-038w\"\u003e90 mm Atlas Fundament\u003c\/a\u003e delivers R 2.37 m²K\/W and the 100 mm version delivers R 2.63 — an 11% uplift for an extra 10 mm of depth. The 90 mm board is the alignment specification for projects where the facade EPS sits at 90 mm; the 100 mm board is the right pick where the facade build-up has been set at 100 mm or where the project targets U-values below the standard Part L baseline.\u003c\/p\u003e","brand":"Renders World","offers":[{"title":"Default Title","offer_id":56400716366199,"sku":null,"price":10.5,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0973\/1375\/1415\/files\/aqua-poliester-eps-board_358a326c-4b37-48d6-9db0-9a98a7e609b5.jpg?v=1767042911"},{"product_id":"eps-foundation-80mm-1-board-0-038w","title":"EPS FOUNDATION 80mm (1 BOARD) 0.038W","description":"\u003cp\u003eWithin the \u003ca href=\"\/collections\/xps-insulationboards\"\u003eXPS insulation boards\u003c\/a\u003e range, Atlas Fundament 80 mm is the standard specification for foundation and basement walls — the depth most domestic new-builds and EWI retrofits actually order. The board delivers a thermal conductivity of \u003cstrong\u003eλ 0.038 W\/mK\u003c\/strong\u003e in a closed-cell foundation-grade structure, measuring 600 × 1250 mm with rebated edges and covering 0.75 m² per board.\u003c\/p\u003e\n\u003ch2 id=\"what-atlas-fundament-80mm-does-in-a-uk-ewi-system\"\u003eWhat Atlas Fundament 80 mm Does in a UK EWI System\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 80 mm delivers R 2.11 m²K\/W — the thermal resistance most UK foundation specifications actually require to meet current Part L 2021 calculation targets (current at time of writing) on a typical domestic new-build or solid-wall retrofit. At λ 0.038 W\/mK in a closed-cell foundation board, the 80 mm depth handles full foundation wraps, basement perimeter insulation up to 2 m below ground level, and standard plinth-to-DPC build-ups without venturing into the deeper, more cost-sensitive 100 mm-plus territory.\u003c\/p\u003e\n\u003cp\u003eEach board measures 600 × 1250 mm with rebated edges that lock together to form a continuous insulation plane without thermal bridging at the joints — so the moisture-resistant layer reads as a single membrane from one course to the next.\u003c\/p\u003e\n\u003ch2 id=\"why-specifiers-choose-atlas-fundament-80mm-for-uk-walls\"\u003eWhy Specifiers Choose Atlas Fundament 80 mm for UK Walls\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe default foundation specification:\u003c\/strong\u003e R 2.11 m²K\/W sits at the depth most UK domestic projects converge on for Part L calculations — neither under-specified nor over-specified for typical foundation U-value targets.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClosed-cell moisture protection:\u003c\/strong\u003e Permanent resistance to ground moisture and hydrostatic pressure keeps thermal performance constant for the life of the foundation up to 2 m below grade.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRebated edges for joint integrity:\u003c\/strong\u003e Tight overlapping joints reduce the cold-bridge risk that flat-edge boards leave at every horizontal course.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFreeze-thaw stable:\u003c\/strong\u003e Holds full R-value through repeated UK winter cycles in exposed ground-contact and splash-zone positions.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVolume-friendly take-off:\u003c\/strong\u003e 600 × 1250 mm covers 0.75 m² per board, so 1.33 boards per m² makes coverage calculations straightforward across long foundation runs and full basement perimeters.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"thermal-specifications-atlas-fundament-80mm\"\u003eThermal Specifications — Atlas Fundament 80 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003cth\u003eNotes\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal conductivity (λ)\u003c\/td\u003e\n\u003ctd\u003e0.038 W\/mK\u003c\/td\u003e\n\u003ctd\u003eDeclared value for foundation board\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThickness\u003c\/td\u003e\n\u003ctd\u003e80 mm\u003c\/td\u003e\n\u003ctd\u003eStandard Atlas Fundament thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThermal resistance (R)\u003c\/td\u003e\n\u003ctd\u003e2.11 m²K\/W\u003c\/td\u003e\n\u003ctd\u003eAt declared λ × thickness\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReaction to fire\u003c\/td\u003e\n\u003ctd\u003ePer EN 13501-1\u003c\/td\u003e\n\u003ctd\u003eConfirm via current DoP at order\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater absorption\u003c\/td\u003e\n\u003ctd\u003eLow (closed-cell)\u003c\/td\u003e\n\u003ctd\u003eSuitable for permanent ground contact\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"physical-specifications-atlas-fundament-80mm\"\u003ePhysical Specifications — Atlas Fundament 80 mm\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoard dimensions\u003c\/td\u003e\n\u003ctd\u003e600 × 1250 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCoverage per board\u003c\/td\u003e\n\u003ctd\u003e0.75 m²\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEdge profile\u003c\/td\u003e\n\u003ctd\u003eRebated (lap joint)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompressive strength\u003c\/td\u003e\n\u003ctd\u003eFoundation-grade (confirm via TDS at order)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBoards per m²\u003c\/td\u003e\n\u003ctd\u003e1.33 (add 5–10% cutting waste)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 id=\"where-atlas-fundament-80mm-performs-best-wall-types-and-build-up\"\u003eWhere Atlas Fundament 80 mm Performs Best — Wall Types \u0026amp; Build-Up\u003c\/h2\u003e\n\u003cp\u003eThe 80 mm thickness is where Atlas Fundament earns its place as the default foundation board across UK domestic projects. The depth balances thermal performance, build-up height, and cost in the range that most Part L calculations land on — deep enough to deliver a meaningful R-value contribution to the overall foundation U-value, shallow enough to avoid the diminishing returns and detailing complications that come with 100 mm-plus boards.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull foundation wraps:\u003c\/strong\u003e Apply vertically against the external face of the foundation wall from footing level up to the damp-proof course on standard domestic new-builds. Backfill provides permanent mechanical restraint.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBasement perimeter insulation:\u003c\/strong\u003e Use across basement and cellar perimeters up to 2 m below ground level, where ground moisture and hydrostatic pressure rule out open-cell alternatives.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlinth zones on EWI retrofits:\u003c\/strong\u003e Position from ground level up to the DPC line on solid-wall retrofit projects where the facade above is being insulated and rendered fresh.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard floor build-ups with deeper screeds:\u003c\/strong\u003e Lay horizontally over a level slab in ground-floor extensions and heated utility spaces where the floor build-up can absorb 80 mm of insulation plus a finishing screed.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"how-atlas-fundament-80mm-fits-into-a-full-ewi-system\"\u003eHow Atlas Fundament 80 mm Fits Into a Full EWI System\u003c\/h2\u003e\n\u003cp\u003eIn a full external wall insulation build-up, Atlas Fundament 80 mm handles the plinth and foundation zone below DPC, while the main facade above is finished with \u003ca href=\"\/collections\/eps-insulation-boards\"\u003egraphite EPS boards\u003c\/a\u003e bonded with adhesive-and-basecoat and finished with mesh-reinforced render. Bond the 80 mm board with a specialist polyurethane adhesive such as \u003ca href=\"\/products\/ceresit-ct84-xps-foam-850ml\"\u003eCeresit CT84 XPS Foam\u003c\/a\u003e, which cures fast in the cool, damp conditions typical of UK ground-level work.\u003c\/p\u003e\n\u003cp\u003eAbove ground level — particularly on plinth zones exposed to wind uplift — add mechanical fixings from the \u003ca href=\"\/collections\/fixing-accesories\"\u003eEWI fixing accessories range\u003c\/a\u003e at 6–8 plugs per m² to lock long-term bond security. The 80 mm board's increased face area catches more wind load than thinner variants, so mechanical fixings are standard practice on any exposed elevation above grade.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-80mm-compares-to-sibling-foundation-boards\"\u003eHow Atlas Fundament 80 mm Compares to Sibling Foundation Boards\u003c\/h2\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBoard\u003c\/th\u003e\n\u003cth\u003eThickness\u003c\/th\u003e\n\u003cth\u003eR-Value (m²K\/W)\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-30mm-1-board-0-038w\"\u003eAtlas Fundament 30 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e30 mm\u003c\/td\u003e\n\u003ctd\u003e0.79\u003c\/td\u003e\n\u003ctd\u003eScreed underlay, thin plinth, reveal zones\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-50mm-1-board-0-038w\"\u003eAtlas Fundament 50 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e50 mm\u003c\/td\u003e\n\u003ctd\u003e1.32\u003c\/td\u003e\n\u003ctd\u003eFloor insulation, shallow foundation wrap\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAtlas Fundament 80 mm\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e80 mm\u003c\/td\u003e\n\u003ctd\u003e2.11\u003c\/td\u003e\n\u003ctd\u003eStandard foundation, basement walls, Part L target\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003eAtlas Fundament 100 mm\u003c\/a\u003e\u003c\/td\u003e\n\u003ctd\u003e100 mm\u003c\/td\u003e\n\u003ctd\u003e2.63\u003c\/td\u003e\n\u003ctd\u003eDeep foundation wrap, highest thermal target\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eFor projects weighing closed-cell foundation insulation against graphite EPS for the main facade, the \u003ca href=\"\/blogs\/news\/xps-vs-eps-insulation-uk\"\u003eXPS vs EPS comparison guide\u003c\/a\u003e walks through where each material wins across the build-up.\u003c\/p\u003e\n\u003ch2 id=\"how-atlas-fundament-80mm-performs-in-uk-weather\"\u003eHow Atlas Fundament 80 mm Performs in UK Weather — Moisture, Frost, Wind Loads\u003c\/h2\u003e\n\u003cp\u003eThe closed-cell structure keeps long-term water absorption at near-zero, so freeze-thaw cycling across a typical UK winter does not progressively reduce R-value the way it can on open-cell boards exposed to ground moisture. At 2 m below grade, the 80 mm board holds its thermal performance through saturation, drying, and re-saturation cycles for decades — the thermal envelope around the foundation stays continuous regardless of season.\u003c\/p\u003e\n\u003cp\u003eWind-load exposure is a meaningful factor above grade at this thickness. The 80 mm face area catches uplift on exposed plinth runs more readily than 30 mm or 50 mm boards do, and on tall facades or coastal sites the mechanical fixing pattern should be set to the project-specific fixing layout rather than a generic 6 plugs per m² — typical layouts run 8 plugs per m² on exposed corners and edges.\u003c\/p\u003e\n\u003ch2 id=\"handling-and-storage-on-site\"\u003eHandling \u0026amp; Storage on Site\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eKeep dry and shaded:\u003c\/strong\u003e Stack boards flat on a clean, level surface. Cover with sheeting if outdoor storage exceeds a few weeks — prolonged UV softens the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eScore, don't snap:\u003c\/strong\u003e Cut with a fine-tooth saw or sharp blade rather than snapping the rebated edge. A clean cut keeps the bonding face true and protects the closed-cell surface.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrush the rebate before adhesive:\u003c\/strong\u003e Dust on the lap joint breaks the foam adhesive seal; a quick brush gives a full-face bond.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePlan deliveries against pour schedule:\u003c\/strong\u003e The 80 mm board is the volume-runner of the range, so foundation-wrap orders typically arrive on full pallets. Stage delivery to match the bonding sequence so boards do not sit exposed on site longer than necessary.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"certifications-and-compliance-atlas-fundament-80mm\"\u003eCertifications \u0026amp; Compliance — Atlas Fundament 80 mm\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament boards are manufactured to recognised European foundation insulation standards. Reaction to fire is classified under EN 13501-1, and the declared thermal conductivity (λ 0.038 W\/mK) appears on the manufacturer's current Declaration of Performance. For projects requiring specific compressive strength values, water absorption test results, or Approved Document L 2021 calculation inputs (current at time of writing), request the latest DoP at order — exact certified values can vary between production batches and the current Atlas Fundament datasheet is the authoritative reference for compliance submissions.\u003c\/p\u003e\n\u003ch2 id=\"is-atlas-fundament-80mm-right-for-your-project\"\u003eIs Atlas Fundament 80 mm Right for Your Project?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eChoose this thickness if\u003c\/strong\u003e your project targets standard Part L 2021 foundation U-values on a domestic new-build, EWI retrofit, or basement perimeter — 80 mm is the depth most UK calculations land on without over-specifying or under-delivering.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBuild-up height restricted?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-50mm-1-board-0-038w\"\u003eAtlas Fundament 50 mm\u003c\/a\u003e at R 1.32 m²K\/W handles floor insulation under screed and shallow foundation wraps where the slab build-up cannot absorb 80 mm.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTargeting deeper thermal performance?\u003c\/strong\u003e The \u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003eAtlas Fundament 100 mm\u003c\/a\u003e at R 2.63 m²K\/W is the thickness for Passive-leaning new-builds and projects pushing well past current Part L thresholds.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDetailing the plinth-to-facade transition?\u003c\/strong\u003e The \u003ca href=\"\/blogs\/news\/thermal-bridges-plinth-insulation-mould-prevention\"\u003eplinth thermal-bridge guide\u003c\/a\u003e walks through the 100 mm overlap detail that keeps the DPC line condensation-free.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 id=\"what-to-order-next-pack-sizes-lead-times-compatible-components\"\u003eWhat to Order Next — Pack Sizes, Lead Times, Compatible Components\u003c\/h2\u003e\n\u003cp\u003eAtlas Fundament 80 mm is supplied as a single board (0.75 m² coverage) and is the volume-runner of the foundation range — typical full-foundation orders ship on pallets from the Southampton warehouse. For project calculations, allow 1.33 boards per m² plus 5–10% cutting waste. To complete the foundation build-up, order Ceresit CT84 XPS Foam for bonding and a fixing pattern of 6–8 plugs per m² above grade for wind-uplift resistance, with 8 plugs per m² on exposed corners and edges.\u003c\/p\u003e\n\u003ch2 id=\"faq-atlas-fundament-80mm-coverage-compatibility-installation\"\u003eFAQ — Atlas Fundament 80 mm Coverage, Compatibility, Installation\u003c\/h2\u003e\n\u003ch3 id=\"how-many-80mm-atlas-fundament-boards-do-i-need-per-square-metre\"\u003eHow many 80 mm Atlas Fundament boards do I need per square metre?\u003c\/h3\u003e\n\u003cp\u003eEach board covers 0.75 m² (600 × 1250 mm), so 1.33 boards per m² is the base figure. For typical foundation-wrap and basement-perimeter runs, add 5–10% cutting waste for corners, openings, and rebated overlaps, then round up to the nearest full board. On large projects, ordering in full pallets simplifies delivery and pricing.\u003c\/p\u003e\n\u003ch3 id=\"is-80mm-enough-to-meet-part-l-foundation-targets\"\u003eIs 80 mm enough to meet Part L foundation targets?\u003c\/h3\u003e\n\u003cp\u003eFor most standard domestic configurations, 80 mm of Atlas Fundament (R 2.11 m²K\/W) brings a foundation wall or basement perimeter within the range typically required to meet Approved Document L 2021 targets (current at time of writing), subject to a project-specific U-value calculation that accounts for wall construction, ground conditions, and the overall thermal target set by the energy assessment.\u003c\/p\u003e\n\u003ch3 id=\"what-adhesive-bonds-atlas-fundament-80mm-to-a-foundation-wall\"\u003eWhat adhesive bonds Atlas Fundament 80 mm to a foundation wall?\u003c\/h3\u003e\n\u003cp\u003eA specialist polyurethane adhesive such as Ceresit CT84 XPS Foam is the standard route — it cures fast in cool, damp UK ground-level conditions and bonds reliably to closed-cell board surfaces. Apply in continuous beads around the perimeter plus a central bead, brush dust from the rebated edge before placement, and press firmly to spread the foam across the full bonding face.\u003c\/p\u003e\n\u003ch3 id=\"does-80mm-need-mechanical-fixings-above-grade\"\u003eDoes 80 mm need mechanical fixings above grade?\u003c\/h3\u003e\n\u003cp\u003eAbove ground level on plinth zones, yes — the 80 mm board's face area catches enough wind uplift that mechanical fixings are standard practice. Typical layouts run 6 plugs per m² across the field and 8 plugs per m² on exposed corners and edges. Below ground level, backfill provides permanent mechanical restraint and the polyurethane foam adhesive alone is typically sufficient.\u003c\/p\u003e\n\u003ch3 id=\"can-i-use-80mm-atlas-fundament-on-a-facade-above-dpc\"\u003eCan I use 80 mm Atlas Fundament on a facade above DPC?\u003c\/h3\u003e\n\u003cp\u003eThe closed-cell structure limits vapour permeability, so the main facade above DPC typically benefits from graphite EPS or mineral wool rather than foundation-grade board. The 80 mm Atlas Fundament earns its place at the plinth, foundation, and basement perimeter zones where its moisture resistance is the deciding factor — switch to graphite EPS for the elevation above DPC.\u003c\/p\u003e\n\u003ch3 id=\"how-does-80mm-compare-thermally-to-100mm-atlas-fundament\"\u003eHow does 80 mm compare thermally to 100 mm Atlas Fundament?\u003c\/h3\u003e\n\u003cp\u003eAt the same declared λ of 0.038 W\/mK, the 80 mm board delivers R 2.11 m²K\/W and the \u003ca href=\"\/products\/eps-foundation-100mm-1-board-0-038w\"\u003e100 mm Atlas Fundament\u003c\/a\u003e delivers R 2.63 — a 25% uplift in thermal resistance for an extra 20 mm of depth. The 100 mm version is the standard pick for Passive-leaning new-builds and projects pushing past typical Part L thresholds; for projects sitting on the standard threshold, 80 mm is usually the more cost-effective specification.\u003c\/p\u003e","brand":"Renders World","offers":[{"title":"Default Title","offer_id":56400719085943,"sku":null,"price":8.3,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0973\/1375\/1415\/files\/aqua-poliester-eps-board.jpg?v=1767042925"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0973\/1375\/1415\/collections\/aqua-poliester-eps-board_9833a88d-449d-42b6-bbbf-ff5ac6142049.jpg?v=1776430058","url":"https:\/\/renders-world.co.uk\/collections\/xps-insulationboards.oembed","provider":"Renders World","version":"1.0","type":"link"}