Description
Polystyrene EPS Grafit 80mm is the graphite-enhanced polystyrene board Renders World stocks as the main-wall thickness for domestic external wall insulation, and it sits in the upper half of the graphite EPS insulation boards shelf, above the detailing sections and below the deep-retrofit boards.
What the 80 mm Graphite EPS Board Does on a UK Wall
Polystyrene EPS Grafit 80mm declares a thermal conductivity of 0.032 W/mK and a declared thermal resistance of 2.50 m²K/W, which is the section most UK domestic retrofit elevations are insulated at. Both figures are declared for GENDERKA EPS 032 FASADA EXTRA under EN 13163:2012+A1:2015, and the resistance comes from the declared 80 mm row rather than from thickness divided by conductivity.
That declared resistance is what puts this thickness on main-wall area rather than on details. At 2.50 m²K/W the board contributes more than three times what a 30 mm reveal strip contributes, for the same bonding and plugging labour per square metre, which is why an elevation is normally insulated at this depth and only the reveals and returns step down.
- Main-wall area on domestic retrofit, where nothing caps the projection and the section is chosen on performance rather than on clearance.
- Whole-elevation work on solid-wall and over-clad construction, with the thinner boards kept for reveals, soffits and returns.
- New-build rendered walls where the fabric calculation sets the section and 80 mm is the figure it lands on.
Declared Performance: Conductivity, Resistance, Strength and Fire
Every figure below is declared for GENDERKA EPS 032 FASADA EXTRA, technical card W32FE, in its technical data sheet and in its Bydgoszcz Declaration of Performance, at board level and under EN 13163:2012+A1:2015.
| Declared property | Value |
|---|---|
| Thermal conductivity λD | 0.032 W/mK |
| Thermal resistance RD at 80 mm | 2.50 m²K/W |
| Reaction to fire | Class E |
| Bending strength | ≥ 75 kPa |
| Tensile strength perpendicular to faces | ≥ 80 kPa |
| Compressive strength at 10% deformation | Not declared |
| Thickness tolerance | ± 1 mm |
| Length and width tolerance | ± 2 mm |
| Squareness / flatness | ± 2 mm/m / ± 5 mm |
| Dimensional stability, normal conditions | ± 0.2% |
| Dimensional stability at 70 °C | ≤ 2% |
| Designation | T1-L2-W2-Sb2-P5-BS75-DS(N)2-DS(70,-)2-TR80 |
Two GENDERKA graphite grades stand behind this shelf, and at 80 mm they diverge on every headline figure. The 032 grade above declares 0.032 W/mK, 2.50 m²K/W and strengths of 75 and 80 kPa; the EPS 031 FASADA EXTRA PLUS Declaration of Performance from the Wschowa plant declares 0.031 W/mK, 2.55 m²K/W and 100 kPa on both strengths. The stricter set is published here, and the purchasing instruction is short: state the grade on the order and take the Declaration of Performance from the supplying plant's own document, because a specification written against 031 figures is not satisfied by 032 boards.
Compressive strength is the figure most often assumed on an insulation board. Both Declarations of Performance carry no declared value for it, so this board is specified for facade duty; a plinth taking backfill, paving or traffic loads calls for a board declared for compression instead. Declared resistance is likewise a board property and not a wall U-value — the wall figure comes out of the build-up calculation set out in the U-value and insulation thickness calculation guide, which is also where the thickness for a given target is settled.
Reaction to fire class E is declared for the board as tested. A finished rendered wall is assessed as a complete system, so the wall's fire performance comes from the system holder and the project fire strategy, and the board class stays on the specification as a board class.
Why UK Specifiers Choose the 80 mm Section
- 2.50 m²K/W declared at 80 mm: the main-wall step, reached at a conductivity of 0.032 W/mK, so the section stays shallower than a white board needs for the same declared resistance.
- Same labour per square metre as a thinner board: bonding, the 24-hour wait and plugging do not change with section, so depth bought here is the cheapest performance on the elevation.
- ± 1 mm on thickness and ± 2 mm/m on squareness: tight tolerances close butt joints cleanly across a full elevation, keeping the rasping pass light rather than corrective.
- Declared stability of ± 0.2% and ≤ 2% at 70 °C: a steel-grey board runs warm on a south elevation, and stability at 70 °C is the declared figure that speaks to that condition.
- Ordered by the single board: elevation quantities can be matched to a survey rather than rounded up to pallets, and cutting allowance sits where the details actually are.
How to Install Polystyrene EPS Grafit 80mm — Bonding, Fixing, Reinforcement
Fitting Polystyrene EPS Grafit 80mm follows the manufacturer's sequence for grey boards, and two instructions carry most of the risk: the adhesive family and the wait before drilling.
- Sand the bonding face immediately before fixing. The data sheet recommends abrading the board surface to raise adhesion, and on graphite boards that pass works best done as each board goes up rather than in a batch beforehand.
- Bond with a permitted adhesive only: cement-based adhesives intended for grey graphite boards, polyurethane foams, or water-dispersion bituminous compounds, taken from the EPS adhesives basecoats range and used to its own data sheet for coverage and open time.
- Keep organic solvents away from the boards in storage and on the working face, which rules out several general-purpose site sealants, cleaners and thinners.
- Wait at least 24 hours before mechanical fixing. Plugging is carried out no earlier than 24 hours after bonding; fixings come from the insulation fixing accessories range, and both plug length and pattern are set by the fixing manufacturer's table and the project wind-load calculation rather than by a rule of thumb — the fixing pattern and spacing guide explains how that layout is derived, and the plug length for an 80 mm board is confirmed against the plug manufacturer's own table before ordering.
- Build the reinforced layer next. With boards bonded, plugged and rasped flat, the reinforced layer goes on with rendering mesh embedded in fresh basecoat, in the sequence described in the EWI system build-up and layers guide.
Storage, Solar Protection and Site Handling
Graphite boards need shading, and on a whole-elevation job the stack is on site long enough for it to matter.
- Shade the boards, absolutely: the steel-grey colour means the surface is protected from direct sunlight, brief and prolonged, in storage and during installation — opaque sheeting over the stack and fixing off a shaded face are the working version of that instruction.
- Keep the packs dry: pallets arrive shrink-wrapped but not weatherproof, so on-site cover is the customer's step and a worthwhile one before the first bonded course goes up.
- Store away from ignition sources, solvents and their vapours, and protect boards from mechanical damage in transit and on the stack.
- Work to the declared flatness: with ± 5 mm on file, a straightedge across the fixed face before rasping shows where the basecoat would otherwise be asked to carry the correction.
How the 80 mm Compares With the 50 mm and 90 mm Grafit Boards
| Board | Declared RD | Where it earns its place |
|---|---|---|
| EPS Grafit 50 mm | 1.55 m²K/W | Parapet returns, depth-restricted elevations |
| EPS Grafit 80 mm (this board) | 2.50 m²K/W | Main-wall area on domestic retrofit |
| EPS Grafit 90 mm | 2.80 m²K/W | Main wall where the target needs more section |
All three are declared from the same document at the same conductivity, so the choice is one of section and declared resistance alone: 1.55, 2.50 and 2.80 m²K/W as the board deepens. The 10 mm step from 80 to 90 mm adds 0.30 m²K/W for no change in installation method, which is the arithmetic worth putting in front of a designer before the section is fixed.
Price, Pack Format and Delivery Terms
The listed price is £5.60 per board, August 2026, for the 1000 × 500 mm format shown on the listing, with the board currently listed as available. One board covers 0.5 m², so £5.60 ÷ 0.5 m² = £11.20 per m² of wall at 80 mm, board only, before adhesive, fixings and the reinforced layer. No VAT label is displayed on the price endpoint, so confirm the VAT position at checkout or with the sales desk.
- Board and pack: 1000 × 500 mm boards, listed at 7 boards and 3.5 m² per manufacturer pack.
- Processing: orders are processed the same day where stock is available, with restocking times advised where it is not.
- Carriage, site-wide: parcels up to 25 kg next day; pallets up to 1200 kg next day, or two business days on the economy option.
- Delivery is kerbside only, so arrange offloading and a dry, shaded store before the pallet arrives — insulation is bulky rather than heavy, and two people with a covered area handle it comfortably.
- Local delivery runs in the company van up to 15 miles from the Southampton headquarters, with a per-mile charge beyond that to a 60-mile limit.
Is the 80 mm Grafit Board Right for Your Project?
- Specify it for main-wall area on domestic retrofit and rendered new-build, with the thinner sections kept for reveals, soffits and returns on the same elevation.
- Step up to the 90 mm Grafit board where the fabric calculation asks for more, since 2.80 m²K/W comes off the same declared table for the same fixing sequence.
- Drop to the 50 mm Grafit board at parapet returns and wherever a boundary, a planning condition or an existing feature caps the projection.
- Settle the material question first where fire drives the specification: the graphite EPS and mineral wool comparison sets out how the two are declared and assessed.
- Confirm the section against the target, not the board — for new-build work the Future Homes Standard guidance and the fabric calculation decide it, with the declared resistance above as one input.
- Order the grade, the plant and the quantity together so the Declaration of Performance arriving with the delivery matches the boards going on the wall.
FAQ — Ordering and Fitting the 80 mm Graphite EPS Board
How many boards do I need per square metre?
Each 1000 × 500 mm board covers 0.5 m², so 1 m² takes two boards and the listed 7-board pack covers 3.5 m². For an 80 m² elevation that is 80 m² × 2 = 160 boards before waste, plus a cutting allowance sized to the reveals, soffits and service penetrations on the survey rather than a flat percentage.
Which adhesives suit a graphite board?
Cement-based adhesives intended for grey graphite boards, polyurethane foam adhesives, and water-dispersion bituminous compounds are the three families named for this board. Anything containing organic solvents is excluded, and each adhesive's own coverage and open time govern on site.
What changes between the 50 mm, 80 mm and 90 mm boards?
Section and declared thermal resistance change: 1.55, 2.50 and 2.80 m²K/W, from the same declared table at the same conductivity. Bonding, the 24-hour wait and the reinforced layer are identical, so the decision is about available depth and the target the calculation is working to.
Can these boards go below the damp-proof course or under paving?
Compressive strength is not declared for this board, so a plinth carrying backfill, paving or traffic loads is served by a board declared for compression and moisture exposure. Above ground on a facade, this is exactly the duty the board is intended for.
Does class E mean the finished wall carries class E?
Class E belongs to the board as tested and declared. A rendered wall is assessed as a system, so its fire performance comes from the system holder and the project fire strategy, and the board class is quoted as a board class on the specification.
Technical Documentation for This Board