Description
Direct from Genderka's UK warehouse stock, this 10 mm graphite EPS board delivers a declared λD of 0.031 W/mK in the slimmest profile in the EPS 031 Fasada Extra Plus range, with 60 boards per pack covering 30 m² of reveal returns, lintel soffits, and thermal-bridge junctions on a full UK EWI build-up.
What EPS Grafit 10 mm Does in a UK EWI System
EPS Grafit 10 mm is a graphite-enhanced polystyrene detailing board certified to EN 13163, delivering λD 0.031 W/mK and R 0.30 m²K/W in a slim profile for reveal returns, lintel soffits, and thermal-bridge closure in EWI build-ups. Each 1000 × 500 mm panel sits within the graphite EPS insulation board range as the dedicated junction product, specified where main-wall boards physically cannot fit but where an uninsulated masonry edge would otherwise undermine the system U-value.
On a typical UK domestic retrofit, reveal depths of 100 to 215 mm leave just enough room behind the window frame for a 10 mm graphite strip plus basecoat and finish. Specify it alongside the main-wall boards in one procurement run, and the elevation finishes as a single continuous insulated plane rather than a wall punctuated by cold edges at every opening.
Why Specifiers Choose EPS Grafit 10 mm for UK Walls
- λD 0.031 W/mK in a 10 mm profile: among the lowest declared lambda in the volume EWI market, delivered in the slimmest available thickness, so reveal cold bridges close without reducing the visible opening or fouling the window frame.
- Sixty boards per pack, 30 m² coverage: one pack typically covers every reveal, soffit, and return on a three-bedroom semi-detached retrofit, with margin for cutting waste around arched heads.
- Identical mechanical spec to thicker siblings: CS70, BS100, and TR100 mean the adhesive bond holds securely and the main-wall fixing schedule transfers directly to the reveal detail.
- Lightweight handling in confined spaces: at around 15 kg/m³ density, each board weighs roughly 75 grams, practical to position single-handed inside reveal returns at scaffold height.
- Slim build-up preserves façade proportions: 10 mm of graphite EPS contributes the thermal performance of about 12.5 mm of standard white EPS, keeping reveal depth, sightlines, and oversill projections close to the original elevation.
- UK warehouse stock for next-working-day dispatch: Renders World ships the slim variant alongside the main-wall thicknesses, so reveal material arrives with the rest of the EWI consignment rather than as a separate back-order.
- Full Declaration of Performance traceability: each batch carries a factory-specific DoP, supporting Building Control sign-off and PAS 2035 retrofit audits.
Thermal Specifications — λ, R-Value, Reaction to Fire
| Property | Value |
|---|---|
| Declared Thermal Conductivity (λD) | 0.031 W/mK |
| Thermal Resistance (RD) at 10 mm | 0.30 m²K/W |
| Reaction to Fire (EN 13501-1) | Euroclass E |
| Classification String (EN 13163) | T1-L2-W2-Sb2-P5-BS100-DS(N)2-DS(70,-)2-TR100 |
| Equivalent White EPS Thickness | ≈ 12.5 mm at λ 0.038 W/mK |
The R-value of 0.30 m²K/W places this board in the detailing band rather than the primary insulation band; its contribution concentrates at the junction psi-value (Ψ) rather than the main-wall U-value. For the method that ties reveal insulation to dwelling fabric efficiency under current Approved Document L guidance, the U-value calculation guide for wall insulation thickness walks through both elements together.
Physical Specifications — Density, Mechanical Strength, Dimensions
| Property | Value |
|---|---|
| Manufacturer | Genderka Sp. z o.o. |
| Product Range | EPS 031 Fasada Extra Plus |
| Thickness | 10 mm |
| Board Dimensions | 1000 mm × 500 mm |
| Coverage per Board | 0.50 m² |
| Boards per Pack | 60 |
| Pack Coverage | 30.0 m² |
| Density | 15 kg/m³ |
| Compressive Strength (CS) | ≥ 70 kPa |
| Bending Strength (BS) | ≥ 100 kPa (BS100) |
| Tensile Strength (TR) | ≥ 100 kPa (TR100) |
| Dimensional Stability — Normal | ± 0.2 % (DS(N)2) |
| Dimensional Stability — 70 °C | ≤ 2 % (DS(70,-)2) |
| Colour | Steel grey (graphite) |
| Standard | EN 13163:2012+A1:2015 |
Where EPS Grafit 10 mm Performs Best — Reveals, Soffits, Junctions
The 10 mm board earns its place in four zones of a UK EWI build-up, each defined by limited depth and outsized influence on envelope performance. Reveal returns lead: the 100 to 215 mm of exposed masonry between the main wall face and the window frame is the most common cold-bridge location on a domestic façade, and lining it with 10 mm of graphite EPS before basecoat closes the bridge without shrinking the visible opening.
Soffit and lintel returns follow the same logic. Above the window head, the horizontal masonry plane meets the underside of any lintel or projecting course, creating a continuous edge that needs insulating to keep the envelope unbroken; the 10 mm thickness fits beneath soffit boards and around lintel projections without fouling rainwater goods.
- Window and door reveals: the primary use case, wrapping the masonry edge between main-wall insulation and the frame to eliminate the localised cold bridge.
- Soffit and lintel returns: closing the horizontal thermal bridge above window heads where standard-thickness boards cannot physically fit.
- Column, pilaster, and service-riser boxing: insulating structural projections and service penetrations that cannot accept thicker boards.
- Levelling shim on uneven substrates: behind thicker main-wall boards, the 10 mm panel corrects minor surface irregularities before adhesive application.
How EPS Grafit 10 mm Fits Into a Full EWI System
Within the layered build-up, the 10 mm board installs after the main-wall boards are bonded and before basecoat goes on. Apply adhesive from the EPS adhesives and basecoats range full-bed to the back face — perimeter-and-dab is unsuitable on a profile this thin — then press the strip onto the prepared reveal or junction. Mechanical fixings are rarely specified for the 10 mm board alone, because the surrounding main-wall boards and the window frame restrain it; where the specification does require one, a short plug from the fixing accessories range handles the duty.
Once bonded, the basecoat reinforcement layer wraps continuously from the main wall face around the reveal return with embedded fibreglass mesh, creating a monolithic crack-resistant surface. The full sequence, from substrate preparation through to the decorative finish, is set out in the complete EWI system build-up and layers guide, and the densities most UK installers work to are covered in the insulation board fixing pattern and spacing guide.
How EPS Grafit 10 mm Compares to Sibling EPS Boards
| Variant | Key Spec | When to Choose |
|---|---|---|
| EPS Grafit 10 mm (this board) | R 0.30 m²K/W · 60/pack · 30 m² | Tight reveal returns and junction strips |
| EPS Grafit 20 mm | R 0.60 m²K/W · 30/pack · 15 m² | Soffits and lintel returns with more depth |
| EPS Grafit 30 mm | R 0.95 m²K/W · 20/pack · 10 m² | Entry-thickness overlays where cost matters |
All three slim-band thicknesses share the same graphite bead technology and mechanical specification, so the choice comes down to depth available behind the frame and the R-value the junction psi-calculation calls for. The 10 mm board wins where reveal depth is genuinely the constraint, and the 20 mm and 30 mm options take over once the geometry allows.
How EPS Grafit 10 mm Performs in UK Weather — Moisture, Frost, Wind
The board's W2 water absorption classification and DS(70,-)2 dimensional stability mean it holds declared performance through UK seasonal cycling, where wind-driven rain and freeze-thaw stress concentrate at reveal and lintel edges. The closed-cell graphite matrix absorbs negligible bulk moisture, and the BS100 bending strength accommodates thermal movement between summer surface temperatures and winter lows without cracking at the joint with main-wall boards.
One handling note matters on UK sites. The steel-grey graphite surface absorbs solar radiation faster than white EPS, so packs left in direct sun on warm days can heat enough to soften the outer bead layer. Keep packs under opaque sheeting until needed and fix boards the same working day they are unwrapped, a small discipline that protects the adhesion key through subsequent freeze-thaw cycling.
Pro Tips From UK Installers Using EPS Grafit 10 mm
Three habits separate a fast, clean reveal install from one that generates callbacks. None appear on the technical data sheet, and all come from the way experienced UK applicators sequence work on multi-property programmes.
- Pre-cut reveal strips at ground level: measure reveal depth at three points per opening, then cut the full allocation on a jig at scaffold base before lifting boards. On-scaffold productivity rises and waste drops.
- Light rasp before adhesive: a quick mechanical key with an EPS rasp lifts adhesive contact above the 40 % minimum without chasing it with extra mortar, useful in tight returns where visible adhesive thickness must stay low.
- Full-bed adhesive, never perimeter-and-dab: on a 10 mm profile the dab pattern leaves voids that weaken long-term adhesion, so butter the entire back face for reliable contact.
- Carry strips in a tool bucket: avoids handling full-size boards inside scaffold reveals, prevents corner damage, and keeps cut edges clean for tight basecoat detailing.
- Wrap mesh continuously from wall to reveal: embed the same fibreglass mesh around the return without breaking the lap, the detail that prevents micro-cracking where the two planes meet.
Handling and Storage on Site
Stack packs flat on a level surface rather than on edge; at 10 mm the boards flex more than thicker siblings, and edge-stacking can warp them over a few days. Keep packs under opaque sheeting until the working face is ready, both to prevent UV softening of the graphite surface and to hold boards at ambient temperature for predictable adhesive open-time. A sharp knife and a straight edge give the cleanest cuts at this thickness; a hot-wire cutter works but tends to over-melt the narrow cross-section if the feed rate slows below a steady pass.
Certifications and Compliance — EN 13163, Euroclass E
- EN 13163:2012+A1:2015: the harmonised European standard for factory-made expanded polystyrene in buildings, covering declared thermal conductivity, dimensional tolerances, mechanical strength, and water absorption.
- Reaction to Fire — Euroclass E: typically suitable within EWI systems on residential buildings below 18 metres, where the project fire strategy permits Euroclass E with approved fire-barrier detailing under current Approved Document B guidance.
- CE Marking and Declaration of Performance: each production batch carries a factory-specific DoP, supporting full traceability for Building Control inspections and PAS 2035 retrofit audits.
- Reveal detailing under Part L: insulating reveals with graphite EPS supports the psi-value (Ψ) calculation at window and door junctions under current Approved Document L guidance, contributing to dwelling fabric energy efficiency.
Is EPS Grafit 10 mm Right for Your Project?
- Specify EPS Grafit 10 mm for reveal returns and junction details on EWI build-ups using graphite EPS on the main wall, where reveal depth prevents thicker boards but cold-bridge closure remains a requirement.
- Step up to the 20 mm Grafit board for soffits and lintel returns where 20 mm of depth is available and a higher junction R-value supports the psi-value calculation.
- Move to main-wall thicknesses for the primary insulated plane, where the thicker boards in the same range cover most UK domestic retrofit U-value targets under current Approved Document L.
- Switch to mineral wool slabs where the project fire strategy requires non-combustible A1-rated insulation across the whole build-up, typically on residential buildings above 18 metres.
- Confirm thickness against the U-value target using the Future Homes Standard 2026 requirements guide for new-build work and Approved Document L for retrofit programmes.
What to Order Next — Pack Sizes, Lead Times, Compatible Components
One pack of 60 boards covers 30 m² of reveal and junction detailing, typically enough for all openings on a three-bedroom semi-detached retrofit with 5 to 10 % cutting margin. Pair the order with the matching adhesive from the EPS adhesives and basecoats range and the appropriate short fixing plug from the fixing accessories range if the specification calls for mechanical retention. Renders World holds UK warehouse stock for next-working-day dispatch on full-pack quantities ordered before midday, so the reveal material arrives with the rest of the EWI consignment rather than as a separate delivery.
FAQ — EPS Grafit 10 mm Coverage, Compatibility, Installation
How many 10 mm boards come in a pack, and what area does one pack cover?
A pack contains 60 boards, each 1000 × 500 mm, giving 30.0 m² of total coverage. For a typical three-bedroom semi-detached retrofit, one pack usually covers all reveal returns, soffit insulation, and lintel detailing across every opening, with a 5 to 10 % allowance for cutting waste around arched heads or non-standard dimensions.
Does the 10 mm board need mechanical fixings, or is adhesive enough?
For reveal applications, full-bed adhesive contact is typically sufficient, because the surrounding main-wall insulation and the window frame mechanically restrain the board. Aim for at least 80 % adhesive contact across the back face for a reliable bond. Where the specification explicitly requires mechanical retention, for example on exposed soffits with no surrounding restraint, a short fixing plug handles the duty, with embedment depth confirmed against the masonry behind the strip.
How does the 10 mm board compare to the 20 mm and 30 mm variants?
All three share λD 0.031 W/mK and identical mechanical properties (CS70, BS100, TR100). The difference is R-value and pack count: 10 mm gives R 0.30 m²K/W at 60 boards per pack, 20 mm doubles to R 0.60 at 30 per pack, and 30 mm reaches R 0.95 at 20 per pack. Choose by depth available at the junction: 10 mm for tight reveals, 20 mm for soffits and lintels, 30 mm for slightly deeper overlays.
Can the 10 mm board be used as primary wall insulation?
At R 0.30 m²K/W, the 10 mm board is a detailing product rather than a primary insulation layer. Approved Document L wall U-value targets require substantially thicker insulation across the main wall area. This board performs best as a reveal, junction, and return product complementing main-wall boards in the thicker bands of the same range.
What is the best way to cut and shape the board on site?
A sharp knife and a straight edge give the cleanest cuts at this thickness, scored once on the graphite face and snapped back. A hot-wire cutter works for repetitive reveal strips but needs a steady feed rate to avoid over-melting the narrow cross-section. For curved details around arched heads, a fine-toothed handsaw produces accurate results without crumbling the bead structure at the cut line.
What fire classification applies when specifying 10 mm graphite EPS in the UK?
The board carries a Euroclass E reaction-to-fire classification under EN 13501-1 and is typically suitable for residential buildings below 18 metres, where the project fire strategy permits Euroclass E with approved fire-barrier detailing under current Approved Document B guidance. For taller buildings or higher-risk façades requiring non-combustible A1-rated insulation, mineral wool replaces EPS across the build-up. Confirm classification with the designer and Building Control at design stage.
Is the board recyclable, and how should off-cuts be managed?
Graphite EPS is fully recyclable through specialist polystyrene recovery programmes, and the graphite additive does not affect recyclability. Collect reveal off-cuts in a dedicated bag and return them through a polystyrene granulation route rather than landfill. The closed material loop reduces site waste and supports the embodied-carbon credentials that increasingly feature in retrofit-grant and PAS 2035 reporting.
Technical Documentation — EPS Grafit 10 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