Description
Graphite boards at 30 mm do two jobs on a UK facade: they close lintel and reveal returns that a main-wall slab cannot reach, and they laminate onto a thicker board where a build-up needs a non-standard depth. Polystyrene EPS Grafit 30mm carries a declared thermal resistance of 0.90 m²K/W, taken from the manufacturer's own declared table rather than from thickness divided by lambda.
Where the 30mm Graphite Board Earns Its Place on a UK Facade
Polystyrene EPS Grafit 30mm is a graphite-loaded expanded polystyrene board declaring λD 0.032 W/mK and 0.90 m²K/W of thermal resistance at 30 mm, the thickness UK installers fit at lintels, reveals and soffits. It is one thickness in the graphite EPS insulation boards range, which runs from reveal strips up to deep-retrofit slabs.
The manufacturer's technical sheet names the uses this board is made for, and they line up closely with the detailing work a UK installer meets on a solid-wall job. Renders World stocks the slim thicknesses alongside the main-wall pallets for that reason: the junctions consume a small area but decide how tidy the finished reveal looks.
- Walls in bonded external insulation systems — the board's primary declared use, as the insulation layer beneath a reinforced basecoat and render.
- Lintels and window reveals — named on the sheet as a distinct application, which is where a 30 mm profile fits without crowding the glazing line.
- Ring beams as permanent formwork under render, keeping the beam face flush with the insulated wall.
- Soffits insulated from below within a bonded system, where depth is tight and the board is fixed overhead.
- Walls with cladding and a ventilated cavity, where the board sits behind a separate rain screen.
Why Specifiers Choose the 30mm Thickness
Selection at this thickness turns on geometry and declared numbers rather than on marketing grades. Five reasons come up repeatedly on trade orders.
- 0.90 m²K/W declared at 30 mm from the manufacturer's declared resistance table, so the figure entering a fabric calculation is the declared one rather than a derived one.
- λD 0.032 W/mK across every thickness in the type, meaning a junction board and a main-wall board share the same declared conductivity and the calculation stays consistent.
- Tolerances tight enough for junction work — thickness to ±1 mm and flatness to ±5 mm, which is what keeps a reveal return flush with the board face beside it.
- Dimensional stability of ±0.2 % in normal conditions and ≤2 % under the specified temperature and humidity test, both declared on the sheet and the declaration of performance.
- One adhesive and fixing routine carries across the thicknesses, so the bedding pattern used on the main wall transfers to the junction boards without a second product on the pallet.
Declared Specifications, and What the Sheet Leaves Undeclared
| Property | Declared value |
|---|---|
| Declared thermal conductivity λD | 0.032 W/mK |
| Declared thermal resistance RD at 30 mm | 0.90 m²K/W |
| Reaction to fire, board | Class E |
| Bending strength | BS75, ≥ 75 kPa |
| Tensile strength perpendicular to faces | TR80, ≥ 80 kPa |
| Dimensional stability, normal conditions | DS(N)2, ± 0.2 % |
| Dimensional stability, temperature and humidity test | DS(70,-)2, ≤ 2 % |
| Thickness, length and width tolerance | T1 ± 1 mm, L2 ± 2 mm, W2 ± 2 mm |
| Squareness and flatness | ± 2 mm/m and ± 5 mm |
| Designation | EPS EN 13163 T1-L2-W2-Sb2-P5-BS75-DS(N)2-DS(70,-)2-TR80 |
| Compressive stress at 10 % deformation | Not declared |
| Water absorption | Not declared |
| Density | Not stated on the sheet |
Every figure above is transcribed from the technical sheet and the declaration of performance for EPS 032 Fasada Extra, both dated to the manufacturer and read this session. The three undeclared lines matter as much as the declared ones, because a compressive strength or a density quoted for this board would have no document standing behind it.
Reading the Designation String Correctly
The W2 inside the designation is a width tolerance class of ±2 mm, not a water-absorption result — the declaration lists water absorption by immersion and by diffusion as undeclared. Anyone building a moisture assessment reads that as a board with no declared water figure, which is normal for a facade EPS sitting above damp-proof level behind a render.
Reaction to fire is declared as Class E for the board, and the declaration also states that the classification does not change with age. The rendered wall it sits in is classified separately by whoever holds the system, so take the build-up figure from the system holder and compare materials first in the graphite EPS and mineral wool facade comparison.
Confirming the Declared Type at Delivery
Two graphite facade types circulate under similar grey-board descriptions, and the difference is worth a glance at the paperwork. The document on file for this group is EPS 032 Fasada Extra at λD 0.032 W/mK and R 0.90 m²K/W at 30 mm with BS75 and TR80; the same manufacturer separately declares EPS 031 Fasada Extra Plus at λD 0.031 W/mK and R 0.95 m²K/W with BS100 and TR100.
This page publishes the EPS 032 figures, the lower of the two, so a calculation built on them holds whichever type arrives. Check the declared type printed on the pack label against your specification when the pallet lands, and the fabric figures need no revisiting later. The method for feeding declared resistance into a wall calculation is set out in the U-value and insulation thickness calculation guide.
How to Install 30mm Boards at Lintels, Reveals and Soffits
Bonding is where a slim board rewards care, and the sheet is specific about what may touch it. Grey graphite boards take cement-based adhesives formulated for graphite boards, polyurethane foam adhesives, or water-dispersion bitumen masses, each used to its own manufacturer's instructions — a cement-based product from the EPS adhesives basecoats range covers the junction and main-wall work in one mix.
Sanding the board face immediately before bonding is recommended on the sheet, and it makes a measurable difference to grip on a small return where there is little area to spare. Keep organic solvents away from the boards entirely, since solvent-bearing products attack the bead structure.
- Grind the bonding face with a rasp or abrasive board just before buttering, then bed the board to full contact so no void sits under a 30 mm profile.
- Leave mechanical fixing until at least 24 hours after bonding, the earliest point the sheet allows plugging, using short plugs from the insulation fixing accessories range where the specification calls for them.
- Work to the declared tolerances — ±1 mm on thickness and ±5 mm on flatness — by rasping the joint line flush before the basecoat rather than filling it afterwards.
- Wrap the reinforced layer continuously around the return with fibreglass reinforcing mesh embedded in the basecoat, so the two planes move as one surface.
- Keep packs sheeted from direct sun, briefly and long term, which the sheet requires because of the steel-grey colour, and fix boards the day they are unwrapped.
The sequence that follows — basecoat, mesh, primer, render — sits in the EWI system build-up and layers guide, and fixing density across a board face is covered in the insulation board fixing pattern and spacing guide. Both are worth reading before the first pack is opened, because the junction detail is set by the main-wall layout around it.
How the 30mm Compares With Neighbouring Thicknesses
| Board | Declared RD | When to choose it |
|---|---|---|
| EPS Grafit 20 mm | 0.60 m²K/W | Tight reveals where a deeper profile fouls the frame |
| EPS Grafit 30 mm, this board | 0.90 m²K/W | Lintels, soffits and composite top-up layers |
| EPS Grafit 50 mm | 1.55 m²K/W | Depth-constrained elevations carrying insulation duty |
All three declare the same λD 0.032 W/mK and the same mechanical classes, so the only variable across the table is declared resistance against available depth. The step from 20 mm to 30 mm adds 0.30 m²K/W for 10 mm of depth, which is usually the deciding arithmetic at a window head.
Deeper thicknesses in the same type carry the main wall, and the 30 mm board is the one that laminates onto them when a total depth has to land on an exact figure. Where that combination is planned, dry-fit the two boards at the opening before any adhesive is mixed.
What to Order Alongside It, and How It Ships
The published format for this board is 1000 × 500 mm at 20 boards per pack, 10 m² per pack, read from this product page rather than lifted from the manufacturer sheet, whose pack table is written against its own agreed formats. Renders World lists no price, stock state or lead time in the data this page could read, so treat quantity as the planning figure and confirm cost and availability directly.
- Order processing runs the same day where stock is available, with the customer service team advising on restocking or alternatives.
- Small parcels up to 25 kg ship next day by courier; pallets up to 1200 kg go next day, or two business days on the economy option.
- Deliveries are curbside, so arrange handling from the roadside and keep pallets covered, as the shrink wrap is not weatherproof.
- Pair the boards with adhesive and mesh on the same order, so the junction material and the reinforcing layer arrive together rather than in two consignments.
Is This the Right Board for the Job?
- Specify 30 mm where a lintel, reveal, ring beam or soffit needs an insulated face and the declared 0.90 m²K/W fits the depth available at that detail.
- Use it as a top-up layer laminated onto a thicker board where a build-up must reach an exact total depth, with the reinforced layer taken across the whole composite face.
- Step up to the EPS Grafit 80 mm board for main-wall duty on a domestic retrofit, keeping 30 mm for the junctions around it.
- Take the fire question to the system holder where the facade classification governs the specification, since Class E is declared for the board and not for the finished wall.
- Confirm the thickness against a calculation rather than a rule of thumb, using the Future Homes Standard 2026 insulation guide for new-build context.
Ready to order, or sizing a whole elevation? Compare the other graphite board thicknesses and add this pack to the same delivery, and the Renders World team can price the full board schedule from your areas.
FAQ — Pack Quantities, Adhesives, Comparisons and Fire Class
How many packs cover a reveal and lintel schedule?
Work from area, then add waste. A 40 m run of reveals at 0.3 m deep is 40 × 0.3 = 12 m²; at 10 m² per pack that is 12 ÷ 10 = 1.2 packs, and a 10 % cutting allowance takes it to 13.2 m², so two packs are ordered. Complex profiles and short offcuts push waste higher than 10 %, so measure per elevation rather than per building.
Which adhesives may be used with these grey boards?
The sheet permits cement-based adhesives formulated for graphite boards, polyurethane foam adhesives, and bitumen masses based on water dispersion, each applied to its own product instructions. Anything containing organic solvents is kept away from the boards altogether, and mechanical fixing waits at least 24 hours after bonding.
What does the 30 mm give over the 20 mm board?
Declared resistance rises from 0.60 to 0.90 m²K/W for 10 mm of extra depth, with identical declared conductivity and mechanical classes either side. Depth at the opening usually settles it: where the frame allows 30 mm, the deeper board is the better use of the same labour.
Can 30 mm serve as the main insulation layer?
At 0.90 m²K/W it suits junction and composite duty, and main-wall thicknesses are chosen by calculation across the whole build-up rather than by a single board figure. The calculation guide linked above shows how declared resistances stack, and the deeper boards in the same type carry the wall.
Is the Class E rating the rating of the finished wall?
No — Class E is declared for the board on its own, tested as a product, and it stays a board property whatever sits over it. A finished render system is classified as an assembly by the organisation that holds that system, and that document is the one a designer relies on.
Technical Documentation