POLYSTYRENE EPS GRAFIT 10mm

Graphite EPS detailing boards earn their keep at the edges of a build-up, where main-wall thicknesses simply run out of room. This slim board sits in the Renders World graphite EPS insulation boards range as the strip that closes reveals, soffits and junctions before the reinforcement layer goes on.

What the Grafit 10mm Board Closes on a UK EWI Build-Up

Polystyrene EPS Grafit 10mm is a graphite-enhanced expanded polystyrene detailing board declaring a thermal resistance of 0.30 m²K/W at 10 mm under EN 13163:2012+A1:2015, sized for reveal returns and lintel soffits where main-wall boards will not fit. That resistance is a detailing figure, not a main-wall one, and its value shows up in the junction calculation rather than the wall U-value.

Fitting it is a sequencing decision more than a thermal one. Boards go on after the main-wall insulation is bonded and before the basecoat, so the reinforcement layer can wrap from the wall face around the return in one continuous pass.

• Window and door reveals — the masonry edge between main-wall insulation and the frame, lined before basecoat so the opening keeps its width.
• Soffit and lintel returns — the horizontal plane above the head, where standard thicknesses foul the frame or the rainwater goods.
• Columns, pilasters and service boxing — projections that cannot physically accept a main-wall board.
• Levelling strips — behind thicker boards, to bring a slightly irregular substrate back into plane.

Why Specifiers Fit Graphite EPS at Reveals and Soffits

The board is chosen for continuity rather than headline performance. Keeping the same graphite material at the junction as on the main wall means one adhesive system and one finish across the elevation.

• Declared resistance at the detail: 0.30 m²K/W at 10 mm appears identically on both GENDERKA declarations read for this range, so the junction is an insulated element rather than bare masonry.
• Same material as the main wall: grey graphite EPS to EN 13163:2012+A1:2015, bonded with the same grey-board adhesives, avoiding a mixed-material joint at the most detailed part of the façade.
• Slim enough to keep the opening: reveal width, sightlines and oversill projection stay close to the original elevation, which matters on terraces and in conservation areas.
• Plant-specific Declaration of Performance: GENDERKA declares this range separately from five production plants, so the paperwork can be matched to the batch supplied for Building Control.
• Supplied with the main-wall order: Renders World carries the slim variant alongside the thicker boards, so detailing material arrives with the consignment instead of as a follow-on.

Declared Specifications — What the Two GENDERKA Documents Say

Two GENDERKA declarations are open against Polystyrene EPS Grafit 10mm and they are not the same range. The record for this board points at EPS 032 Fasada Extra, while the document previously published on this page is the EPS 031 Fasada Extra Plus declaration. Both were fetched, so both are shown with their scopes.

Declared property	EPS 032 Fasada Extra	EPS 031 Fasada Extra Plus
Thermal conductivity λD	0.032 W/mK	0.031 W/mK
Thermal resistance at 10 mm	0.30 m²K/W	0.30 m²K/W
Bending strength	≥ 75 kPa	≥ 100 kPa
Tensile strength, perpendicular	≥ 80 kPa	≥ 100 kPa
Compressive strength	no performance declared	no performance declared
Reaction to fire	E	E
Harmonised standard	EN 13163:2012+A1:2015	EN 13163:2012+A1:2015

 

Order on the stricter column. Where a specification depends on the lambda or the tensile figure, take 0.032 W/mK and ≥ 80 kPa and confirm the range and plant against the delivery note, and the detail holds whichever board arrives. The 10 mm resistance is the one figure both documents agree on, which is why it leads here. For the method that turns a declared resistance into a wall figure, the U-value and insulation thickness calculation guide works through the build-up properly.

Reaction to Fire, at Board Scope

Both declarations give the board a reaction-to-fire class of E under EN 13163:2012+A1:2015. That is the class of the board on its own and not the class of the rendered build-up around it, which is set by the whole specified system; the fire strategy for the elevation is agreed with the designer and the system holder, and the board is specified inside it.

Weather Exposure and Dimensional Stability

The EPS 032 technical card carries the designation string T1-L2-W2-Sb2-P5-BS75-DS(N)2-DS(70,-)2-TR80, which is where the water-absorption class W2 and the dimensional-stability limits sit: ± 0.2 % in normal laboratory conditions and ≤ 2 % under the elevated temperature and humidity test. Those tolerances are what keep a reveal strip flat against seasonal movement once the basecoat has locked it in.

How to Install the 10mm Board — Adhesive, Sequence, Timing

The manufacturer's instruction for grey boards is narrower than for white EPS, and following it is what protects the bond. Two points do most of the work: the right adhesive family, and patience before drilling.

1. Use a dedicated grey-board adhesive — cement-based, polyurethane foam, or a water-dispersion bituminous mass, as specified for graphite boards. Options sit in the EPS adhesives basecoats range.
2. Rasp the face before bonding. GENDERKA recommends abrading the board surface immediately before adhesive contact to raise adhesion, and it takes seconds on a strip this size.
3. Butter the full back face on a profile this thin, then press the strip onto the prepared reveal or soffit and check it against the main-wall plane.
4. Leave mechanical fixing for 24 hours. The card sets fixing no earlier than 24 h after bonding; where the detail calls for a plug at all, it comes from the insulation fixing accessories range, and the layout logic is in the board fixing pattern and spacing guide.
5. Wrap the reinforcement layer continuously from wall face to return, embedding fibreglass mesh without breaking the lap. The full layer order is set out in the EWI system build-up and layers guide.

Storage and Handling for Grey Boards

The technical card is unambiguous on one point: because of the steel-grey colour, the board surface must be protected from direct sunlight, briefly as well as long-term. Keep packs sheeted until the working face is ready and the adhesion key stays intact. Organic solvents and solvent-bearing products stay away from the boards entirely, and stacking flat rather than on edge keeps a 10 mm strip true.

How the 10mm Board Compares With the 20mm and 30mm Boards

Board	Declared resistance	Where it belongs
Grafit 10mm (this board)	0.30 m²K/W	Tight reveals and junction strips
EPS Grafit 20mm	0.60 m²K/W	Soffits and lintel returns with depth
EPS Grafit 30mm	0.90 m²K/W	Deeper overlays and reveal linings

 

All three sit in the same range and take the same adhesive, so the choice is geometry first and resistance second. The 20 mm and 30 mm figures are the declared values for those thicknesses; the 30 mm cell carries the stricter of the two declarations, because the two documents differ at that thickness while agreeing at 10 mm and 20 mm.

Choosing the Thickness Your Detail Needs

• Stay at 10 mm where reveal depth behind the frame is the binding constraint and the strip has to take basecoat and finish as well.
• Step to 20 mm for soffits and lintel returns, where the depth exists and the junction calculation wants the extra 0.30 m²K/W.
• Move to main-wall thicknesses such as the 50mm Grafit board for the primary insulated plane, and treat the wall target as a build-up calculation rather than a thickness.
• Check the target first on new build using the Future Homes Standard 2026 insulation guide, then size the detail boards around the main-wall decision.

Ordering, Delivery and What Arrives at the Kerb

Board format on this listing is 1000 × 500 mm. Pack make-up for UK supply — the number of boards and the pack area — is confirmed at order rather than quoted here, because the current GENDERKA card tabulates packs for its own standard formats and the UK pack is made up by the distributor.

Renders World processes orders the same day where stock is available, and the sales team confirms the delivery method and cost after the order because dimensions vary too much for automatic calculation. Courier parcels up to 25 kg run next day, pallets next day or two business days on the economy option, and local delivery is free within 15 miles of the Southampton base on qualifying orders. All deliveries are kerbside only, and pallets are shrink-wrapped but not weatherproof — for graphite EPS that means arranging cover and a pair of hands at the kerb, which is a five-minute job worth planning for.

FAQ — Fitting, Compatibility and Compliance

Which adhesive suits a graphite board at a reveal?

A grey-board adhesive from the cement-based, polyurethane foam or water-dispersion bituminous families, applied to the full back face on a strip this thin. The EPS adhesives basecoats range covers all three routes, and the adhesive manufacturer's own card governs open time and coverage.

How does the 10 mm board differ from the 20 mm in practice?

Declared resistance doubles from 0.30 to 0.60 m²K/W, and everything else — material, adhesive, fixing logic — stays the same. Depth available behind the frame usually settles it before the numbers do.

Can it be used as primary wall insulation?

At 0.30 m²K/W it belongs at the detail rather than the main wall, where a far higher resistance is needed. Main-wall thicknesses in the same range handle that duty, and the wall figure is always established by build-up calculation.

What does the class E reaction to fire mean when specifying?

It describes the board as declared under EN 13163:2012+A1:2015, and it says nothing about the finished wall, whose rating belongs to the complete system. The route through is to confirm the fire strategy and the system specification with the designer at design stage, and specify the board within it.

Technical Documentation

• GENDERKA EPS 032 Fasada Extra — technical card (PDF)
• GENDERKA EPS 032 Fasada Extra — Declaration of Performance, Bydgoszcz plant (PDF)
• GENDERKA EPS 031 Fasada Extra Plus — Declaration of Performance, Wschowa plant (PDF)

The declaration matching the batch supplied, and the plant that issued it, is confirmed at order.