Description
Polystyrene EPS Grafit 100mm is the graphite façade board most solid-wall work standardises on — one step deeper than the 90mm board and the last depth before the range jumps to 150mm. The declared figure to specify against is a thermal resistance of 3.10 m²K/W.
Where the 100mm Graphite Board Fits on a UK Façade
Polystyrene EPS Grafit 100mm installs as the thermal layer of a bonded render system, declared to EN 13163:2012+A1:2015 with a thermal resistance of 3.10 m²K/W, which is the figure a wall U-value calculation takes. Renders World holds it inside the graphite EPS insulation boards ladder, between the reveal strips at the shallow end and the deep-retrofit depths above.
The practical appeal of 100mm is repeatability. It is a round number on a take-off sheet, it lands on the same declared row for every elevation of a terrace, and it uses exactly the same bonding, fixing and reinforced-layer sequence as the boards either side of it, so a change of thickness never rewrites a method statement.
The manufacturer's data sheet lists the uses this board type is intended for, and main-wall insulation is only the first of them:
- walls in bonded render systems, which is the principal façade application;
- walls behind cladding with a ventilated air gap;
- lintels and reveals, where the 0.5 m² board cuts down without waste;
- soffits insulated from below within a render system;
- ring beams and reinforced concrete slabs used as permanent shuttering under render.
Why Specifiers Order 100mm Rather Than a Neighbouring Depth
Six things settle the depth once the elevation has been surveyed, and each of them reads off a declaration rather than off a brochure.
- Declared resistance of 3.10 m²K/W at 100mm, taken from the declared table rather than calculated, so the number entering a wall U-value calculation is the one the declaration of performance carries.
- Declared λD 0.032 W/mK, constant across the range, which means moving up or down the thickness ladder changes the declared resistance and nothing else in the specification.
- A 0.30 m²K/W step up from the 90mm board for 10mm of extra projection — usually the cheapest resistance available on a wall that has the reveal depth to spare.
- Reaction to fire class E, declared for the board itself. That is a board property; the behaviour of a finished rendered wall is a system question, which the graphite EPS and mineral wool comparison takes up.
- Tight geometry classes — thickness ±1 mm, length and width ±2 mm, squareness ±2 mm/m, flatness ±5 mm — which is what allows butt joints to close cleanly across a long elevation instead of opening up under the mesh.
- A documented adhesive restriction. Only products dedicated to grey graphite boards are permitted, keeping the choice inside the EPS adhesives basecoats range rather than open to any bag on the van.
Declared Figures for the 100mm Board — Resistance, Lambda, Fire, Tolerances
Every value below comes from the Genderka EPS 032 Fasada Extra data sheet and its declaration of performance, both fetched this session, with the scope of each declaration stated alongside it.
| Property | Declared value | Scope of the declaration |
|---|---|---|
| Harmonised standard | EN 13163:2012+A1:2015 | EPS 032 Fasada Extra, all thicknesses |
| Thermal conductivity λD | 0.032 W/mK | EPS 032 Fasada Extra, all thicknesses |
| Thermal resistance RD at 100 mm | 3.10 m²K/W | Declared table, 100 mm row |
| Reaction to fire | Class E | The board, not a rendered build-up |
| Bending strength | ≥ 75 kPa | EPS 032 Fasada Extra |
| Tensile strength, perpendicular to faces | ≥ 80 kPa | EPS 032 Fasada Extra |
| Compressive stress at 10% deformation | Not declared (NPD) | Declaration of performance, Table 1 |
| Water absorption, immersion and diffusion | Not declared (NPD) | Declaration of performance, Table 1 |
| Freeze–thaw resistance | Not declared (NPD) | Declaration of performance, Table 1 |
| Thickness / width tolerance | ± 1 mm / ± 2 mm | EPS 032 Fasada Extra |
| Dimensional stability, 70 °C condition | ≤ 2% | EPS 032 Fasada Extra |
| Board format | 1000 × 500 mm | This product listing |
Three blanks in that table are worth reading as carefully as the figures. Compressive strength, water absorption and freeze–thaw resistance are all declared NPD, so no value for any of them appears on this page. Where a project needs a declared compressive or water-absorption figure — a plinth, a paved perimeter, anything below damp-proof course — that calls for a board declared for the duty rather than a façade board asked to cover it.
One point of care on the classification code, because it is regularly misread: the W2 class in the designation string is a width tolerance of ±2 mm, not a water-absorption class. Nothing on this declaration supports a water-absorption claim of any kind.
Two Genderka Declarations, and Which One to Calculate With
Two documents circulate for the grey Genderka façade board and they do not declare the same numbers. EPS 032 Fasada Extra declares 0.032 W/mK, 3.10 m²K/W at 100 mm, bending ≥75 kPa and tensile ≥80 kPa. EPS 031 Fasada Extra Plus, declared for the Wschowa plant, gives 0.031 W/mK, 3.20 m²K/W at 100 mm and 100 kPa for both strength classes.
This page publishes the stricter set and names both, which is the right way round for a calculation that has to survive Building Control. As a purchasing instruction: specify against 0.032 W/mK and 3.10 m²K/W, and ask the Renders World trade desk to confirm the range name and production plant printed on the delivery paperwork before a U-value is signed off. If the paperwork comes back as Fasada Extra Plus, the calculation gains a little margin rather than losing any.
Why the Declared Row Beats Dividing Thickness by Lambda
Dividing thickness by conductivity gives 0.100 m ÷ 0.032 W/mK = 3.125 m²K/W, while the declared row for 100 mm reads 3.10 m²K/W. The gap is rounding, and it always favours the calculation that was never declared. Only the declared value appears on the declaration of performance, so only the declared value belongs in a compliance file — which is also why no wall U-value is printed on this page. A U-value belongs to a whole build-up of substrate, adhesive, board, reinforced layer and render; the assembly method sits in the EWI layer build-up guide, and the energy efficiency requirements themselves are set by Approved Document L, Volume 1: Dwellings, now published in a 2026 edition alongside earlier editions that still apply to earlier work.
How to Install 100mm Boards — Bonding, the 24-Hour Wait, Plugging
The sequence follows the manufacturer's installation section, and the timings in it shape the programme rather than padding a data sheet.
- Abrade the bonding face. The sheet recommends sanding the board surface immediately before bonding to raise mortar adhesion — fast work with a rasp, and it lifts the smooth factory skin that graphite bead leaves behind.
- Bond with a product dedicated to grey boards. Permitted types are cement-based adhesives, polyurethane foam adhesives and water-dispersion bitumen compounds intended for graphite boards, each used to its own data sheet.
- Wait at least 24 hours before mechanical fixing. Plugging comes no earlier than a day after bonding, so it plans best as an overnight break rather than an afternoon push — worth sequencing two elevations so nobody stands still.
- Plug to the system designer's pattern. Counts and layout come from the system figure, never a rule of thumb: the fixing pattern and spacing guide explains how it is arrived at, the hardware sits in the insulation fixing accessories range, and plug length is read from the manufacturer's own table by the method in the plug length guide.
- Build the reinforced layer. Basecoat with alkali-resistant rendering mesh embedded in it follows the fixing stage, and it is the layer the render finish keys into.
Two site conditions run right through storage and installation, and both are unconditional in the document: keep organic solvents and their vapours away from the boards, and protect the steel-grey faces from direct sunlight, briefly and over time. Opaque sheeting handles the second while the scaffold is up, and it also keeps the faces cool enough to be comfortable to cut.
Comparing 100mm With the 90mm and 150mm Graphite Boards
All three sit on the same declared table, so they differ in declared resistance and in how far the finished wall projects. Nothing else in the specification moves between them.
| Board | Declared resistance | Where it earns its place |
|---|---|---|
| 90mm graphite EPS board | 2.80 m²K/W | Elevations where reveals and sills will not give up the last 10mm |
| 100mm (this board) | 3.10 m²K/W | The repeatable default on solid masonry with normal reveal depth |
| 150mm graphite EPS board | 4.65 m²K/W | Deep retrofit, where detailing is redesigned rather than preserved |
The arithmetic is worth seeing plainly: 3.10 − 2.80 = 0.30 m²K/W for the step from 90mm, and 4.65 − 3.10 = 1.55 m²K/W for the step to 150mm. That is why 100mm is so often the settled answer — the step down saves very little depth, and the step up buys a great deal of resistance but changes every window reveal, sill projection and verge detail on the building.
Choosing the 100mm Board for Your Elevation
Four checks settle the order.
- Fit 100mm where the reveal and sill survey allows the projection and the calculation needs more than the 90mm board's declared 2.80 m²K/W contributes.
- Let the calculation set the target, not the thickness. New-build targets are covered in the Future Homes Standard 2026 guide; retrofit work answers to Approved Document L and the project's own assessment.
- Check the funding route before ordering on grant-supported work, since scheme paperwork often fixes the specification — the EWI grant funding guide sets out what the schemes ask for.
- Take the non-combustible route where the fire strategy requires it. This board is declared class E, and the stone wool comparison above is the place to start that conversation.
Ordering the 100mm Board — Price, Stock and Delivery
The listing shows £7.00 as displayed in August 2026 and the board is in stock at the same date. The listing does not state which selling unit that price covers, so no per-square-metre figure is published here; confirm with Renders World whether it buys one 1000 × 500 mm board or a pack, and the quantity arithmetic follows straight from the answer.
- Delivery is costed after the order. Dimensions and weights vary too much for automatic calculation, so the customer service team quotes the cheapest method and confirms it.
- Parcels up to 25 kg travel next working day by courier; pallets up to 1200 kg go next working day, or two business days on the economy option.
- All deliveries are curbside and pallets are shrink-wrapped rather than weatherproofed, so arrange somewhere dry to move the boards to on arrival.
FAQ — Quantities, Adhesives and Compliance for the 100mm Board
How many boards cover a square metre, and how many for an 80 m² elevation?
At 1000 × 500 mm each board covers 1.000 m × 0.500 m = 0.50 m², so 1 m² ÷ 0.50 m² = 2 boards per m², and an 80 m² elevation takes 80 ÷ 0.50 = 160 boards before any cutting allowance. Set the allowance from the surveyed elevation rather than a flat percentage, since reveals, soffits and service penetrations differ sharply between house types.
Which adhesives may be used with a grey graphite board?
The data sheet permits cement-based adhesives, polyurethane foam adhesives and water-dispersion bitumen compounds, in each case products dedicated to graphite (grey) boards and applied to their own manufacturer's instructions. It also asks for the bonding face to be abraded immediately beforehand, which is the step most often skipped on graphite work.
What changes between the 90mm, 100mm and 150mm boards?
Only declared resistance and depth: 2.80 m²K/W at 90mm, 3.10 m²K/W at 100mm and 4.65 m²K/W at 150mm, all at the same declared 0.032 W/mK and the same declared strength classes. Bonding, the 24-hour wait, plugging and the reinforced layer are identical, so the method statement carries across unchanged.
How soon after bonding can the boards be plugged?
Mechanical fixing follows no earlier than 24 hours after bonding, with the reinforced layer after that. Two restrictions apply throughout: no contact with organic solvents or their vapours, and no direct sunlight on the grey faces, short-term or long-term, in storage or on the wall.
What fire class does the 100mm board carry?
Reaction to fire is declared as class E under EN 13163:2012+A1:2015. That class describes the board, not a finished wall, because a rendered build-up is assessed as a system with its own evidence — so where a fire strategy calls for non-combustible insulation, a stone wool slab is the specification to price instead.
Why does this page publish 0.032 W/mK when another sheet says 0.031?
Two Genderka declarations cover grey façade board, Fasada Extra at 0.032 W/mK and Fasada Extra Plus at 0.031 W/mK, and this page publishes the stricter one so that no calculation rests on the more generous figure. Confirm the range and plant on your paperwork at order, and the calculation can be tightened afterwards if the Plus declaration turns out to apply.
Technical Documentation for the Grey Graphite Façade Board
- Genderka EPS 032 Fasada Extra — technical data sheet (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 divergent range document
Declarations are issued per production plant, and Genderka declares from five of them, so the document that belongs on a compliance file is the one covering the plant that supplied the delivery. Confirm it at order and it can be filed alongside the calculation.