Description
This 90mm EPS insulation is a grey graphite polystyrene board, 1000 × 500 mm, for insulating the outside of a wall before it is rendered. At 90 mm it is made for the open face of the wall, the large areas between windows, doors and corners. It is one of eleven thicknesses in the Renders World graphite board range, so thinner insulation from the same system can line the reveals.
One sheet of this insulation covers 0.5 m²; declared thermal conductivity is ≤ 0.031 W/mK.
90mm EPS Insulation: What You Get
Every board of 90mm EPS insulation is 1000 mm long, 500 mm wide and 90 mm deep. Graphite added during production makes the polystyrene grey and raises its insulating performance, so this EPS does more work for its depth than white polystyrene.
| Property | Declared value |
|---|---|
| Thermal conductivity λD | ≤ 0.031 W/mK |
| Reaction to fire | Class E |
| Thickness tolerance | T1 (± 1 mm) |
| Length and width tolerance | L2, W2 (± 2 mm) |
| Squareness | S5 (± 5 mm per 1000 mm) |
| Flatness | P5 (5 mm) |
| Bending strength | BS100 (≥ 100 kPa) |
| Tensile strength perpendicular to the faces | TR100 (≥ 100 kPa) |
| Dimensional stability, normal conditions | DS(N)2 (≤ 0.2 %) |
| Dimensional stability, set temperature and humidity | DS(70,-)2 (≤ 2 %) |
The Class E rating applies to the insulation alone. Once meshed and rendered, the wall is classified as a system, and that classification belongs to the system specification. To see what 90 mm does for your own wall, follow the U-value and insulation thickness guide.
A Board for the Façade
90mm EPS insulation is built for one place, the outside face of a wall:
- bonded to the masonry, fixed, meshed and finished with render;
- not laid flat under a screed or a slab, and not buried in the ground.
Below ground, on the foundations and around the plinth, different insulation takes over. Renders World stocks a 90 mm foundation board for that zone, sold as its own product.
Why Choose a 90mm Graphite Board
- Depth for the main wall. Ninety millimetres is a full insulation layer for the open façade, not a lining for openings.
- Graphite efficiency. At ≤ 0.031 W/mK the EPS insulates more per millimetre than plain white polystyrene.
- Quick to set out. Each sheet is half a square metre, which makes counting simple, and six fill a pack.
- Straight joints. ± 1 mm on thickness and ± 2 mm on length and width keep the EPS flush and the joints tight.
- Takes the render layer. The EPS is rated for at least 100 kPa in bending and in tension.
- Little movement. In normal conditions the size changes by 0.2 % at most.
- Works with the rest of the range. From 20 mm up the format is the same, so the reveal insulation meets the 90 mm wall insulation cleanly.
Where a 90mm Board Goes
- External walls, bonded and rendered, or fixed by the light-dry method.
- Stud walls, across the outside face.
- Cavity walls, in the enclosed or the ventilated slot.
- Loggias and balconies deep enough for a 90 mm build-up.
Suitable backgrounds: concrete, cement and cement-lime plaster, bare brick, block and hollow block in ceramic or silicate, and aerated concrete.
How Many Boards of 90mm EPS Insulation to Order
Each square metre of wall takes a pair of sheets of 90mm EPS insulation. A full pack holds 6 boards and covers 3.00 m².
- A 24 m² elevation needs 24 ÷ 0.5 = 48 boards, which is exactly 8 full packs.
- Take the window and door openings off the wall area, then order the reveal insulation in a thinner size as a separate item.
- Keep the larger offcuts of EPS for the corners and the top course under the eaves.
Fitting the Board
Bond 90mm EPS insulation with a cement-based or polyurethane adhesive from the adhesives and basecoats for insulation boards. Start on a wall that is frost-free, load-bearing, even and sound, cleaned of dust, dirt, lime, oil, grease, wax and old emulsion or oil paint.
- Prime and make good. An over-absorbent surface, weak cement or cement-lime plaster and rough aerated or cinder block are primed with Uni-Grunt priming emulsion. Large holes and hollows are filled first with ZW 330 mortar or Plastering Mix M, listed in the shop as One Coat Dash Cover.
- Edge strip and dabs. Put a continuous band of adhesive at least 3 cm wide around the EPS and 6 to 8 dabs of 8 to 12 cm in the field. Aim for at least 40 % coverage, rising to 60 % after pressing.
- Fix at once. Push the EPS into place with no more than 10 mm of adhesive behind it. On an even, smooth wall you can instead notch-trowel the adhesive across the whole back, for a 2 to 5 mm bed after fixing.
- Rub down before the base coat. The surface has to be frost-free, flat, clean and stable; sanding and dusting graphite insulation first is advised.
Mechanical fixings and the mesh layer follow. See the insulation fixing accessories, the board fixing pattern and spacing guide and the EWI build-up and layers guide.
Keep Graphite Boards Out of the Sun
On a bright day 90mm EPS insulation needs the same three habits as all graphite insulation:
- Fix it cool. EPS that heats up during fixing or while the adhesive first sets can lose its bond.
- Stack it in shade. Keep the packs wrapped and away from direct sun, which can warp the EPS.
- Cover the scaffold. Use scaffold sheeting and stop work in snow, rain or a strong wind.
Long exposure, above all to UV, can leave a yellow tint on the face; sand it off before the base coat. Keep acetone, nitro thinners, benzene and other solvents away, as they dissolve polystyrene.
On a wall of doubtful strength, test first: glue 8 to 10 polystyrene cubes, 10 × 10 cm, at different points and pull them off after 3 days. If the cube breaks inside itself, the wall is fine; if it brings adhesive or part of the wall with it, the insulation design must set out the remedy.
90mm Among the Other Thicknesses
From 20 mm up the sizes share one 1000 × 500 mm format:
| Thickness | Sheets per m² | Full pack |
|---|---|---|
| 10 mm | 2 | order by the sheet |
| 20 mm | 2 | 30 sheets, 15.00 m² |
| 30 mm | 2 | 20 sheets, 10.00 m² |
| 50 mm | 2 | 12 sheets, 6.00 m² |
| 80 mm | 2 | 7 sheets, 3.50 m² |
| 90 mm (this board) | 2 | 6 sheets, 3.00 m² |
| 100 mm | 2 | order by the sheet |
| 150 mm | 2 | 4 sheets, 2.00 m² |
| 160 mm | 2 | 3 sheets, 1.50 m² |
| 180 mm | 2 | 3 sheets, 1.50 m² |
| 200 mm | 2 | 3 sheets, 1.50 m² |
Whether your wall needs 90mm EPS insulation or another depth comes from a U-value calculation for the full build-up; the 80 mm and 100 mm insulation sits either side of this one.
Ordering, Delivery and Returns
Renders World processes orders the same day when the stock is there.
- Delivery: quoted by the team after the order; parcels up to 25 kg go next day, pallets next day or in two business days on the economy option, always kerbside.
- Collection: from the counter at Unit 9A, Central Trading Estate, Southampton SO14 5JP, Monday to Friday 7am to 5pm and Saturday 7am to 12pm.
- Returns: goods bought directly from Renders World can go back within 14 days in their original condition; special orders and promotion purchases are excluded.
FAQ
What size is one board?
1000 × 500 × 90 mm, covering 0.5 m². Two boards make a square metre.
How many boards are in a pack?
6 boards, which cover 3.00 m².
Can I use it for floor insulation?
No. This is a façade board. Floors need a board designed for floor loads, and the foundations and plinth take the 90 mm foundation board.
What is its thermal conductivity?
λD ≤ 0.031 W/mK. The U-value depends on every layer of the wall, so it is worked out for the whole build-up.
Which adhesive should I use?
Cement-based or polyurethane, applied as an edge band with dabs to cover at least 40 % of the insulation, never more than 10 mm thick.
Is this the same as a 90 mm PIR board?
No. This is expanded polystyrene with graphite, made to be bonded, meshed and rendered on an external wall.
What goes in the window reveals?
Thinner insulation from the same range, cut to the depth the frame allows, so the insulation carries on into the opening.
Technical Documentation