Description
Polystyrene EPS Grafit 150mm is the thickness UK deep-retrofit and new-build specifications converge on, and the figure that matters is the declared one: 4.65 m²K/W of thermal resistance from a single 150 mm bonded layer, with every other number on this page taken from the manufacturer's declaration sheets rather than a rule of thumb.
What EPS Grafit 150mm Delivers on a UK Solid Wall
Polystyrene EPS Grafit 150mm carries a declared thermal conductivity of 0.032 W/mK under EN 13163:2012+A1:2015, and at 150 mm that gives 4.65 m²K/W in one bonded layer of a rendered external wall insulation build-up. The board sits at the deep end of the graphite-enhanced EPS insulation boards range, and the practical payoff is depth in one pass: one bonding operation and one fixing pattern instead of doubling thinner boards.
A wall U-value comes from a calculation across the whole build-up, never from the board alone, so 4.65 m²K/W is the input a SAP assessor or Building Control file needs rather than the finished answer. That distinction is what keeps a specification defensible when the assessor asks where the number came from.
- Solid masonry retrofit: brick and block walls where no internal floor area can be lost to insulation.
- Deep new-build masonry: a single 150 mm layer keeps bonding, fixing and rasping to one sequence per elevation.
- Reveal and soffit continuity: thinner boards in the same declared range carry the detail on the same adhesive.
Why Specifiers Choose the 150mm Graphite Board
Five properties decide this board on a UK facade, and each is a declared line on the manufacturer's technical card rather than a marketing claim.
- Declared λD 0.032 W/mK: the graphite content lowers conductivity against standard white expanded polystyrene insulation, so a given resistance is reached in less depth.
- 4.65 m²K/W declared at 150 mm: taken from the declared resistance table, not from thickness divided by lambda, which is the figure a calculation will accept.
- Bending strength ≥ 75 kPa: the board stays flat while it waits between bonding and fixing, which matters on a full-height lift.
- Tensile strength ≥ 80 kPa perpendicular to the faces: the property the adhesive and the reinforced layer both pull against.
- Thickness tolerance ± 1 mm: board-to-board steps stay small, so the basecoat covers a flatter plane and rasping time drops.
Declared Specifications to EN 13163:2012+A1:2015
Every value below is copied from the GENDERKA EPS 032 FASADA EXTRA technical card W32FE and its Declaration of Performance, and applies to the board as a product, not to a rendered build-up containing it.
| Declared property | Value |
|---|---|
| Thermal conductivity λD | 0.032 W/mK |
| Declared thermal resistance at 150 mm | 4.65 m²K/W |
| Reaction to fire (board) | Class E |
| Bending strength | BS75, ≥ 75 kPa |
| Tensile strength perpendicular to faces | TR80, ≥ 80 kPa |
| Thickness tolerance | T1, ± 1 mm |
| Length and width tolerance | L2 and W2, ± 2 mm |
| Squareness / flatness | Sb2, ± 2 mm/m / P5, ± 5 mm |
| Dimensional stability, laboratory conditions | DS(N)2, ± 0.2 % |
| Dimensional stability, 70 °C | DS(70,-)2, ≤ 2 % |
| Assessment route | System 3, ITB notified body 1488 |
| Board format supplied | 1000 × 500 mm, 4 boards per pack, 2.0 m² |
Two readings worth correcting: W2 is a width tolerance of ± 2 mm, not a water-absorption grade, and water absorption is declared NPD on this DoP, so no absorption figure belongs on the page. Class E is the board's own reaction to fire and is not the classification of the wall it sits in; where a fire strategy calls for non-combustible insulation, the trade-offs at these depths are set out in the graphite EPS and mineral wool facade comparison.
How to Confirm the Declared Range Before You Order
GENDERKA declares two graphite facade ranges whose figures differ, and the previously published version of this page carried the EPS 031 Fasada Extra Plus set. Renders World publishes the stricter of the two declarations here, and both are shown side by side so a specifier can see exactly which line is being relied on.
| Declared property | EPS 032 Fasada Extra (published above) | EPS 031 Fasada Extra Plus |
|---|---|---|
| λD | 0.032 W/mK | 0.031 W/mK |
| Resistance at 150 mm | 4.65 m²K/W | 4.80 m²K/W |
| Bending strength | ≥ 75 kPa | ≥ 100 kPa |
| Tensile strength | ≥ 80 kPa | ≥ 100 kPa |
| Reaction to fire (board) | Class E | Class E |
Ask the trade desk to confirm the range and the producing plant on the order, then take the Declaration of Performance number from the delivery paperwork for the assessment file. Both ranges are declared separately from five GENDERKA plants, so the DoP is confirmed at order rather than quoted from a shelf listing — a step worth getting right where the file will be audited.
How to Install EPS Grafit 150mm Boards
Installation of Polystyrene EPS Grafit 150mm follows the manufacturer's card, and three of its instructions are specific to grey graphite boards rather than general good practice.
- Bond with a dedicated grey-board adhesive — cement-based, polyurethane foam or water-dispersion bitumen — from the EPS adhesives basecoats range; solvent-bearing products attack the bead structure.
- Rasp or sand the bonding face immediately before bedding, which the card recommends specifically to raise adhesion of the mortar to the factory skin.
- Leave a minimum 24 hours before mechanical fixing. Plug the boards no earlier than that, using insulation fixing accessories matched to the substrate.
- Set the pattern from the system designer's fixing schedule, since density and plug length are manufacturer and system figures; the layouts UK installers work to are covered in the board fixing pattern and spacing guide.
- Build the reinforced layer next, embedding mesh from the rendering mesh range before the finish coat. The full sequence and drying intervals sit in the EWI system build-up guide.
On storage the card is unusually firm: the steel-grey face must be protected from direct sunlight, briefly and long term, so keep packs sheeted and out of the sun on the scaffold as well as in the yard. Boards also travel best strapped and lifted by their long edges.
How the 150mm Board Compares With the 100mm and 160mm Siblings
All three thicknesses share one declaration, so the comparison is a straight read of the declared resistance table.
| Board | Declared resistance | When it is the right depth |
|---|---|---|
| 100 mm graphite board | 3.10 m²K/W | Standard retrofit depth, tighter reveals |
| 150 mm (this board) | 4.65 m²K/W | Deep retrofit and fabric-first new build |
| 160 mm graphite board | 5.00 m²K/W | Maximum depth before reveals are reworked |
Stepping from 150 mm to 160 mm buys 0.35 m²K/W of declared resistance for 10 mm of extra build-up, which is the arithmetic that usually decides window reveals and sill depth. How that resistance turns into a wall U-value is set out in the U-value and insulation thickness calculation guide.
Choosing 150mm for Your Project
Four checks settle whether this is the right board on the drawing.
- Specify it when the target resistance needs 4.65 m²K/W from one layer and reveals, sills and verges can absorb 150 mm of build-up.
- Step down to 100 mm where the calculation is satisfied at 3.10 m²K/W and the detailing budget is tight.
- Check the fire strategy first on anything other than low-rise housing; the board's own class is E and the designer decides what the wall requires.
- Model the moisture path on solid walls before committing to depth, using the dew point and condensation risk guide, and read the direction of travel in the Future Homes Standard 2026 guide.
What to Order Alongside the 150mm Boards
Boards alone do not make a build-up. Renders World ships the whole system on one consolidated order, and the trade desk quotes pallet quantities and delivery before anything leaves the warehouse.
- Measure the wall area, divide by 2.0 m² per pack and add 5 to 10 % for cutting around reveals and penetrations.
- Add adhesive, basecoat, mesh and fixings in the quantities the system designer's schedule sets out for a 150 mm board.
- Confirm delivery on the order: orders are processed the same day when stock is held, pallets run next working day or two business days on the economy option, and deliveries are kerbside.
FAQ — EPS Grafit 150mm Coverage, Fixings and Fire
How many packs cover 100 m² of wall?
Each pack holds 4 boards at 1000 × 500 mm and covers 2.0 m². For 100 m²: 100 ÷ 2.0 = 50 packs, plus 10 % for cutting waste = 55 packs. Confirm the pack format against the delivery note before a large order is placed.
Which adhesive and plug suit a 150 mm graphite board?
Adhesive must be one of the types the manufacturer names for grey graphite boards: cement-based, polyurethane foam, or water-dispersion bitumen. Plug length and density come from the fixing manufacturer's own selection table for the substrate and board depth, which is why no length is quoted here.
Is 150 mm or 160 mm the better choice?
The declared resistance rises from 4.65 to 5.00 m²K/W across that 10 mm step. Where the calculation lands inside 4.65 m²K/W, the thinner board keeps reveal and sill detailing simpler; where it does not, 160 mm is the next declared point.
What limits apply during storage and application?
Three declared limits: protect the grey faces from direct sunlight at all times, keep organic solvents away from the boards, and leave at least 24 hours after bonding before mechanical fixing.
Does the class E board decide the wall's fire performance?
Class E is declared for the board on its own. A finished external wall is classified as a build-up by the project fire strategy, so the slab or board class is never carried onto the completed facade.
Technical Documentation — Declared Performance Sheets
All four documents below were retrieved live for this page.