Description
Within the XPS insulation boards 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 λ 0.038 W/mK in a closed-cell foundation-grade structure, measuring 600 × 1250 mm with rebated edges and covering 0.75 m² per board.
What Atlas Fundament 30 mm Does in a UK EWI System
Atlas 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.
Each 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.
Why Specifiers Choose Atlas Fundament 30 mm for UK Walls
- Slimmest profile in the range: 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.
- Closed-cell moisture protection: Permanent resistance to ground moisture and hydrostatic pressure keeps thermal performance constant for the life of the foundation.
- Rebated edges for joint integrity: Tight overlapping joints reduce the cold-bridge risk that flat-edge boards leave at every horizontal course.
- Freeze-thaw stable: Holds full R-value through repeated UK winter cycles in exposed ground-contact and splash-zone positions.
- Low-waste sizing: 600 × 1250 mm covers 0.75 m² per board, simplifying take-off calculations for narrow plinth runs and screed strips.
Thermal Specifications — Atlas Fundament 30 mm
| Parameter | Value | Notes |
|---|---|---|
| Thermal conductivity (λ) | 0.038 W/mK | Declared value for foundation board |
| Thickness | 30 mm | Thinnest in Atlas Fundament range |
| Thermal resistance (R) | 0.79 m²K/W | At declared λ × thickness |
| Reaction to fire | Per EN 13501-1 | Confirm via current DoP at order |
| Water absorption | Low (closed-cell) | Suitable for permanent ground contact |
Physical Specifications — Atlas Fundament 30 mm
| Parameter | Value |
|---|---|
| Board dimensions | 600 × 1250 mm |
| Coverage per board | 0.75 m² |
| Edge profile | Rebated (lap joint) |
| Compressive strength | Foundation-grade (confirm via TDS at order) |
| Boards per m² | 1.33 (add 5–10% cutting waste) |
Where Atlas Fundament 30 mm Performs Best — Wall Types & Build-Up
The 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.
- Screed underlay in cellars and utility rooms: Lay horizontally over a level slab, then pour screed directly above — the closed-cell surface tolerates the wet trade without water uptake.
- Thin plinth upgrades on retrofit: 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.
- Reveal and junction zones: Use as a thin thermal break at foundation-to-reveal transitions where a deeper board would clash with adjacent EPS courses.
- Below-DPC capping strips: Cap exposed concrete kickers or footing tops where a thicker board would project past the facade plane.
How Atlas Fundament 30 mm Fits Into a Full EWI System
In 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 graphite EPS boards bonded with adhesive-and-basecoat and finished with mesh-reinforced render. Bond the 30 mm board with a specialist polyurethane adhesive such as Ceresit CT84 XPS Foam, which cures fast in the cool, damp conditions typical of UK ground-level work.
Above ground level — particularly on plinth zones exposed to wind uplift — add mechanical fixings from the EWI fixing accessories range to lock long-term bond security. Below ground, backfill provides permanent mechanical restraint and the foam adhesive alone is typically sufficient.
How Atlas Fundament 30 mm Compares to Sibling Foundation Boards
| Board | Thickness | R-Value (m²K/W) | Best For |
|---|---|---|---|
| Atlas Fundament 30 mm | 30 mm | 0.79 | Screed underlay, thin plinth, reveal zones |
| Atlas Fundament 50 mm | 50 mm | 1.32 | Floor insulation, shallow foundation wrap |
| Atlas Fundament 80 mm | 80 mm | 2.11 | Standard foundation and basement walls |
| Atlas Fundament 100 mm | 100 mm | 2.63 | Deep foundation wrap, highest thermal target |
For projects weighing closed-cell foundation insulation against graphite EPS for the main facade, the XPS vs EPS comparison guide walks through where each material wins across the build-up.
How Atlas Fundament 30 mm Performs in UK Weather — Moisture, Frost, Wind Loads
The 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.
At 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.
Handling & Storage on Site
- Keep dry and shaded: 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.
- Score, don't snap: 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.
- Brush the rebate before adhesive: Dust on the lap joint breaks the foam adhesive seal; a quick brush gives a full-face bond.
- Stack flat, not on edge: Storing 30 mm boards on edge can cause bowing — flat storage preserves the rebated geometry.
Certifications & Compliance — Atlas Fundament 30 mm
Atlas 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.
Is Atlas Fundament 30 mm Right for Your Project?
- Choose this thickness if 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.
- Need more depth for a full foundation wrap? The Atlas Fundament 80 mm covers standard foundation and basement walls at R 2.11 m²K/W, and the 100 mm version hits R 2.63 for the highest thermal target in the range.
- Working above DPC? Switch to graphite EPS boards for vapour permeability on the main facade.
- Detailing the plinth-to-facade transition? The plinth thermal-bridge guide walks through the 100 mm overlap detail that keeps the DPC line condensation-free.
What to Order Next — Pack Sizes, Lead Times, Compatible Components
Atlas 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.
FAQ — Atlas Fundament 30 mm Coverage, Compatibility, Installation
How many 30 mm Atlas Fundament boards do I need per square metre?
Each 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.
Is 30 mm thick enough for a full foundation wrap?
For 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.
What adhesive bonds Atlas Fundament 30 mm to a foundation wall?
A 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.
Can I use 30 mm Atlas Fundament on a facade above DPC?
The 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.
Does 30 mm need mechanical fixings as well as adhesive?
Below 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.
How does 30 mm compare thermally to 50 mm Atlas Fundament?
At the same declared λ of 0.038 W/mK, the 30 mm board delivers R 0.79 m²K/W and the 50 mm Atlas Fundament 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.