Description
The standard semi-detached retrofit specification, EPS Grafit 100 mm delivers R 3.20 m²K/W at λD 0.031 W/mK and clears the Approved Document L 0.30 W/m²K retrofit target on typical 215 mm solid brick, supplied at 6 boards per pack covering 3.0 m² for trade specifiers and multi-property retrofit programmes.
What EPS Grafit 100 mm Does in a UK EWI System
Unlike the 90 mm board, which lands marginally above the compliance line at 0.31 to 0.33 W/m²K, EPS Grafit 100 mm clears the Approved Document L retrofit target with measurable headroom, delivering λD 0.031 W/mK and R 3.20 m²K/W as the standard semi-detached compliance thickness. Certified to EN 13163, this graphite-enhanced expanded polystyrene board serves as the primary insulation layer in thin-coat render EWI systems on masonry, blockwork, and rendered substrates up to 18 m in height. It sits within the wider graphite EPS insulation board range as the depth at which most UK retrofit projects achieve a clear pass against the 0.30 W/m²K wall U-value target.
Specifiers choose this thickness when the project goal is a defensible, auditable, Building-Control-friendly U-value on common UK housing stock without pushing into the deeper 150 to 200 mm band reserved for Passive House and ultra-low-energy targets. At 100 mm the build-up depth, board weight, and pack coverage all sit at a practical sweet spot for scaffold-mounted application across whole streets of similar semi-detached and terraced properties.
Why Specifiers Choose EPS Grafit 100 mm for UK Walls
- Clear Part L retrofit compliance on 215 mm solid brick: the assembly U-value lands at approximately 0.27 to 0.30 W/m²K, beating the 0.30 W/m²K Approved Document L retrofit target with measurable headroom rather than sitting marginally above it.
- R 3.20 m²K/W from a 100 mm depth: graphite bead chemistry delivers roughly 20 percent better insulation than white EPS at the same thickness, saving around 25 mm of total build-up depth.
- Standardised across multi-property retrofit programmes: recognised by energy assessors, local authority schemes, and Building Control as the proven semi-detached thickness for ECO4 and Warm Homes Plan projects.
- Six-board packs sized for storey-height strips: each pack covers 3.0 m² (1.5 m wide by 2.0 m high), simplifying material movement on scaffold platforms.
- BS100 bending strength and TR100 tensile strength: boards handle confidently at scaffold height and bond reliably to cementitious or polyurethane EWI adhesives under UK wind-load exposure.
- EN 13163 CE-marked with full Declaration of Performance: every pack is traceable to the originating Genderka facility, supporting Building Control evidence packs and PAS 2035 retrofit coordinator records.
- UK-stocked for programme-scale procurement: Renders World holds pallet quantities for whole-street retrofit programmes, typically dispatched next working day with consolidated EWI system orders shipped on a single delivery.
Thermal Specifications — λ, U-Value, Reaction to Fire
| Property | Value |
|---|---|
| Declared thermal conductivity (λD) | 0.031 W/mK |
| Thermal resistance (RD) at 100 mm | 3.20 m²K/W |
| Indicative wall U-value (215 mm solid brick + 100 mm) | 0.27–0.30 W/m²K, subject to calculation |
| Reaction to fire (EN 13501-1) | Euroclass E |
| Classification string | EPS EN 13163 T1-L2-W2-Sb2-P5-BS100-DS(N)2-DS(70,-)2-TR100 |
Under current Approved Document B guidance, Euroclass E EPS is permitted within EWI build-ups on residential buildings below 18 m where the project fire strategy specifies horizontal mineral wool fire barriers at each floor level and around openings. For buildings above 18 m or where the fire strategy requires non-combustible insulation throughout, switch the specification to the mineral wool insulation range, with the selection logic set out in the graphite EPS vs mineral wool 2026 facade guide.
Physical Specifications — Density, Strength, Dimensions
| Property | Value |
|---|---|
| Manufacturer | Genderka Sp. z o.o. |
| Range | EPS 031 Fasada Extra Plus |
| Thickness | 100 mm |
| Board size | 1000 mm × 500 mm |
| Coverage per board | 0.50 m² |
| Boards per pack | 6 |
| Pack coverage | 3.0 m² |
| Density | 15 kg/m³ |
| Bending strength | ≥ 100 kPa (BS100) |
| Tensile strength perpendicular to faces | ≥ 100 kPa (TR100) |
| Dimensional stability (normal) | ± 0.2 % (DS(N)2) |
| Standard | EN 13163:2012+A1:2015 |
Where EPS Grafit 100 mm Performs Best — Wall Types and Build-Up
The 100 mm graphite EPS board is the go-to thickness for projects where compliance, repeatability, and procurement simplicity matter as much as raw thermal performance, so three wall-type scenarios cover the majority of UK use cases.
Semi-Detached Solid Brick Retrofit
On a typical 215 mm solid brick semi-detached with an original U-value around 2.1 W/m²K, wrapping the elevations in 100 mm of graphite EPS reduces the assembly to approximately 0.27 to 0.30 W/m²K, subject to project U-value calculation. This is the specification energy assessors recognise on sight, Building Control sign off with minimal additional evidence, and grant funders accept as a proven compliance pathway.
End-Terrace and Mid-Terrace Properties
Mid-terrace homes with one exposed elevation and end-terrace properties with two benefit from 100 mm as a standardised primary thickness across whole-street programmes. The specification carries across each property unchanged, simplifying surveying, ordering, and post-installation inspection.
Cavity-Wall Over-Cladding for Definitive Compliance
Properties with failed, partial, or unverified cavity fill benefit from 100 mm of external graphite EPS to create a continuous high-performance envelope independent of cavity condition, a definitive route to sub-0.30 W/m²K performance regardless of what sits inside the wall.
How EPS Grafit 100 mm Fits Into a Full EWI System
Boards bond to the prepared substrate with a circumferential-and-spot adhesive bead from the EPS adhesives and basecoats range, aiming for a minimum 40 percent contact area to satisfy wind-load design under BS EN 1991-1-4. Press boards firmly in a running-bond pattern with 200 mm minimum vertical joint offset and butt joints under 2 mm. The board carries enough mass to remain stable during the 24-hour adhesive cure window without propping.
After cure, secure with 6 to 8 mechanical fixings per m² from the fixing accessories range. The matching plug for 100 mm boards on standard masonry is the LTX 140 mm polystyrene fixing plug, providing 30 to 40 mm of embedment beyond the board and adhesive layer. Rasp the outer face to create a basecoat key, then apply reinforcing basecoat with embedded fibreglass mesh and finish with the project's render system. Mesh reinforcement, layer drying intervals, and tie-in detailing for reveals and soffits are covered in the EWI system build-up layers explained guide, and the fixing densities most UK installers work to are detailed in the insulation board fixing pattern and spacing guide.
How EPS Grafit 100 mm Compares to Sibling EPS Boards
| Variant | Key Spec | When to Choose |
|---|---|---|
| EPS Grafit 90 mm | R 2.90 · U ~0.32 · LTX 120 | Solid wall, depth-constrained reveals |
| EPS Grafit 100 mm (this board) | R 3.20 · U ~0.29 · LTX 140 | Semi-detached compliance standard |
| EPS Grafit 150 mm | R 4.80 · U ~0.20 · LTX 180 | Part L 2025, deep / Passive retrofit |
Choose 100 mm when the project needs a clear retrofit compliance pass on standard housing stock with manageable build-up depth. Move down to 90 mm only where reveal proportions or boundary lines force a slimmer profile, and move up to 150 mm when targeting U-values below 0.22 W/m²K or feeding into a Passive House calculation. The detailed thickness calculation methodology sits in the U-value calculation and wall insulation thickness guide.
How EPS Grafit 100 mm Performs in UK Weather — Moisture, Frost, Wind Loads
Graphite EPS has a closed-cell structure with very low water absorption (W2 classification under EN 13163), allowing the board to maintain declared thermal performance through the wet UK heating season when installed within a correctly detailed render or EWI system. Freeze-thaw cycling does not degrade the bead structure, and the material is unaffected by typical UK winter temperatures.
Wind-load resistance is governed by the combined adhesive and mechanical fixing specification rather than the board itself. On standard UK exposure zones the recommended 6 to 8 plugs per m², combined with full-perimeter adhesive contact, delivers reliable retention to BS EN 1991-1-4 design pressures. On exposed coastal or upland sites, increase fixing density to 8 to 10 per m² and verify with the project structural engineer. Condensation risk within the build-up on solid-wall retrofits is covered in the dew point and condensation risk guide.
Pro Tips From UK Installers Using EPS Grafit 100 mm
Three habits separate a smooth first-fix day from a slow one on whole-street programmes. None appear on the technical data sheet, and all come from the way experienced UK applicators handle the standard semi-detached thickness across repetitive elevations.
- Set up a ground-level cutting station: install a jig sized for the property's most common reveal and soffit widths, and pre-cut the full allocation before starting the fix. On repetitive semi-detached elevations this typically saves 30 to 40 minutes of on-scaffold time per property.
- Rasp the bonding face lightly before adhesive: the factory skin on graphite EPS is smoother than on white EPS and benefits from a mechanical key, raising the achieved contact area closer to the 40 percent wind-load target.
- Choose the cutting tool by edge quality required: a fine-tooth handsaw gives the cleanest visible edge for reveals and soffits, while a hot-wire cutter is faster for batch-cutting identical widths across whole elevations.
- Standardise the survey take-off before the first pallet: on whole-street programmes, lock the per-property pack count from one fully measured reference elevation, then adjust only for opening variations rather than re-surveying every plot from scratch.
Handling and Storage on Site
At 100 mm and 15 kg/m³ density each board weighs roughly 0.75 kg, comfortable for single-handed positioning at scaffold height. Store packs flat on a level surface under opaque sheeting, since the steel-grey graphite surface absorbs solar radiation rapidly and prolonged direct sun softens the outer bead layer and reduces adhesion key quality. Lift packs by the strapping or by supporting the long edges rather than the short ends to avoid creasing the outer boards in transit. A fine-tooth handsaw gives the cleanest edge for visible reveal and soffit cuts; a hot-wire cutter is the faster option for batch-cutting identical field widths.
Certifications and Compliance — EN 13163, Euroclass E, Part L
- EN 13163:2012+A1:2015: the harmonised European standard for factory-made expanded polystyrene products, covering declared thermal conductivity, dimensional tolerances, and mechanical strength properties.
- Reaction to fire — Euroclass E (EN 13501-1): suitable for EWI systems on residential buildings below 18 m where the project fire strategy specifies horizontal fire barriers at each floor level, under current Approved Document B guidance.
- CE marking and Declaration of Performance: every pack is traceable to the originating Genderka facility, supporting Building Control evidence packs and PAS 2035 retrofit coordinator records.
- Part L compliance pathway: at R 3.20 m²K/W the board typically delivers wall U-values of 0.27 to 0.30 W/m²K on 215 mm solid brick, clearing the Approved Document L retrofit target subject to project-specific calculation. For the wider regulatory picture see the Future Homes Standard 2026 guide.
Is EPS Grafit 100 mm Right for Your Project?
- Best fit: semi-detached, end-terrace, or mid-terrace property with 215 mm solid brick walls targeting a clear Approved Document L retrofit compliance pass with measurable headroom.
- Slimmer profile alternative: reveal or boundary constraints favour the 90 mm Grafit board within a 90 mm depth where a marginal pass is acceptable.
- Deeper retrofit alternative: Passive House or U-values below 0.22 W/m²K call for the 150 mm Grafit board.
- Fire-strategy alternative: buildings above 18 m or projects requiring non-combustible insulation throughout, specify from the mineral wool insulation range linked in the thermal section above.
- Bundle route: whole-property programmes benefit from sourcing all components through a single consolidated EWI system order with one phased delivery.
What to Order Next — Pack Sizes, Lead Times, Compatible Components
Confirm the surveyed wall area in m², divide by 3.0 m² per pack, and add 5 to 10 percent for cutting waste around reveals, soffits, and service penetrations. Pair each pallet of 100 mm boards with sufficient adhesive and basecoat from the adhesives and basecoats range (typical demand 4 to 5 kg/m² for the adhesive layer and 4 kg/m² for the basecoat layer), plus the LTX 140 mm fixing plug at 6 to 8 fixings per m². Renders World dispatches pallet quantities for whole-property programmes next working day from the Southampton warehouse on consolidated EWI deliveries.
For surveyors, retrofit coordinators, and multi-property programme managers, consolidated take-off sheets, per-m² pricing, and split deliveries phased to scaffold rotation are available on request via the trade desk before the first pallet leaves the warehouse.
FAQ — EPS Grafit 100 mm Thickness, Coverage, Installation
How many packs does a typical semi-detached property require?
A three-bedroom semi-detached property with approximately 80 m² of exposed wall area (after deducting windows and doors) requires roughly 27 to 30 packs of 6 boards, including 5 to 10 percent for cutting waste around reveals, soffits, and service penetrations. Always order against a measured site survey rather than a desktop estimate.
Does 100 mm achieve Part L compliance on standard 215 mm solid brick?
On a typical 215 mm solid brick wall the assembly U-value lands at approximately 0.27 to 0.30 W/m²K, clearing the Approved Document L retrofit target of 0.30 W/m²K subject to project U-value calculation. Fully insulated reveals, soffits, and lintels improve junction psi-values and bring the assembly closer to the 0.26 W/m²K new-build elemental target.
Which fixing plug pairs with the 100 mm board on standard masonry?
The LTX 140 mm polystyrene fixing plug provides the correct embedment for a 100 mm board on standard brick or block substrates, delivering 30 to 40 mm beyond the board and adhesive layer. Install 6 to 8 fixings per m² in the pattern specified for the project's wind-load zone, with fixings positioned at board junctions and across the field area for even load distribution.
Which adhesive bonds graphite EPS to a masonry substrate?
Both cementitious EPS adhesives and polyurethane EWI foam adhesives bond reliably to graphite EPS when the substrate is sound, dust-free, and primed where required. Apply via the circumferential-and-spot method, targeting a minimum 40 percent contact area between adhesive and substrate to satisfy wind-load design.
What is the expected service life within an EWI render system?
Within a correctly detailed render system with intact basecoat and finish, graphite EPS maintains its declared thermal performance throughout the EWI system's typical 30+ year design life. Periodic visual inspection of the render surface for impact damage, with prompt repair of any breaches, preserves long-term insulation performance.
Is the 100 mm board suitable for buildings above 18 m?
For residential buildings above 18 m, current Approved Document B guidance and Building Safety Act provisions typically call for non-combustible (Euroclass A2-s1,d0 or A1) insulation throughout the façade. Switch the specification to a mineral wool slab for these projects, subject to the project fire strategy and designer sign-off.
Technical Documentation — EPS Grafit 100 mm TDS, DoP, Certificates
- Genderka EPS 031 Fasada Extra Plus — Declaration of Performance (PDF)
- Genderka EPS 031 Fasada Extra Plus — Manufacturer Product Page and Technical Data