Description
This 80mm EPS is a grey graphite polystyrene board, 1000 × 500 mm, for external wall insulation under a render finish. Eighty millimetres gives the open wall a proper insulating layer while keeping the build-up moderate, which helps where sills, eaves or a boundary leave limited room. It belongs to the Renders World graphite board range of eleven thicknesses, all cut to the same face size from 20 mm up.
Half a square metre per sheet of 80mm EPS; declared thermal conductivity ≤ 0.031 W/mK.
80mm EPS: What You Get
An 80mm EPS board is 1000 mm long, 500 mm high and 80 mm thick. Graphite is added to the polystyrene as it is made, giving the EPS its grey colour and a better insulation value than white polystyrene of equal thickness.
| 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 %) |
Class E is the rating of the EPS itself. The finished, rendered wall is classified as a whole system, and that rating comes from the system specification. For the U-value an 80 mm layer gives on a real wall, use the U-value and insulation thickness guide.
Wall Insulation, Above Ground
80mm EPS does its job on the wall above the plinth:
- it is bonded and fixed to the façade, then meshed and rendered;
- it does not go under a floor, under paving or into the ground.
Where the insulation continues down over the foundations, the plinth or below ground level, change to the 80 mm foundation board, which Renders World sells as a separate product for those areas.
Why Choose an 80mm Graphite Board
- A real wall layer at a moderate depth. 80 mm insulates the open façade without pushing the face of the wall as far out as the thickest EPS in the range.
- Graphite performance. ≤ 0.031 W/mK gives more insulation from each millimetre than white polystyrene.
- Simple counting. Two boards per square metre and seven to a full pack.
- Close tolerances. ± 1 mm on thickness and ± 2 mm on length and width help the joints close up tight.
- Strong enough for the system. Bending and tensile strength of at least 100 kPa each.
- Stable once fixed. At most 0.2 % change in size in normal conditions.
- Two ways to bond. Cement-based or polyurethane adhesive.
Where an 80mm Board Goes
- External walls, bonded and rendered or fixed by the light-dry method.
- Loggias and balconies with room for an 80 mm layer.
- Stud walls, over the outside face.
- Cavity walls, in the enclosed or the ventilated slot.
It bonds to concrete, cement and cement-lime plaster, bare brick, block and hollow block in ceramic or silicate, and aerated concrete.
How Many Boards of 80mm EPS to Order
Count two boards of 80mm EPS for every square metre of wall. A full pack holds 7 boards and covers 3.50 m².
- A 35 m² rear wall takes 35 ÷ 0.5 = 70 boards, which is 10 full packs.
- Deduct the openings first, then add the thinner reveal EPS as its own line.
Fitting the Board
Use a cement-based or polyurethane adhesive from the adhesives and basecoats for insulation boards. The wall must be frost-free, load-bearing, even and sound, and free of dust, dirt, lime, oil, grease, wax and old emulsion or oil paint.
- Prime and fill. Over-absorbent surfaces, weak cement or cement-lime render and rough aerated or cinder block take a coat of Uni-Grunt priming emulsion. Big hollows and gaps are filled beforehand with ZW 330 mortar or Plastering Mix M, shown in the shop as One Coat Dash Cover.
- Butter the EPS. A continuous edge strip at least 3 cm wide and 6 to 8 dabs of 8 to 12 cm across the middle, covering at least 40 % of the back and 60 % after pressing.
- Press it home. Fix the EPS straight away with a maximum of 10 mm of adhesive behind it. On a smooth, even wall the adhesive may instead be notched over the whole back, leaving 2 to 5 mm once fixed.
- Sand and clean. Before the base coat the EPS must be frost-free, flat, clean and firm; sanding and dusting graphite EPS is advised.
Then come the fixings and the reinforced layer: 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
Three site rules apply to 80mm EPS on a sunny job:
- Don't fix warm EPS. Keep each sheet from heating up while it is fixed and while the adhesive first sets, or it may come loose.
- Store in shade. Leave the EPS wrapped and out of direct sunlight, which can distort it.
- Sheet the scaffold. Use scaffold covers and pause the work in snow, rain or high wind.
Weeks of exposure, UV in particular, can turn the face yellowish; sand it off before the base coat. Solvents such as acetone, nitro thinners and benzene damage polystyrene and must stay well away.
If the wall may be too weak to hold the EPS, bond 8 to 10 polystyrene cubes, 10 × 10 cm, at several points and pull them after 3 days. A clean break inside the cube is a pass; a cube that takes adhesive or part of the wall with it is a fail, and the insulation design has to answer it.
80mm Among the Other Thicknesses
From 20 mm upwards every thickness of EPS uses the same 1000 × 500 mm face, so different depths can share one elevation:
| 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 (this board) | 2 | 7 sheets, 3.50 m² |
| 90 mm | 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 |
The 50 mm and 90 mm sizes are the neighbours of 80mm EPS; which of them suits your wall is a U-value calculation for the whole build-up.
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 × 80 mm, which is 0.5 m². Two boards cover a square metre.
How many boards are in a pack?
7 boards, enough for 3.50 m².
Can I use it for floor insulation?
No. It is made for walls. Floors need a board rated for floor loads, and the plinth and foundations take the 80 mm foundation board.
What is its thermal conductivity?
λD ≤ 0.031 W/mK. The U-value of the wall is calculated from all of its layers.
Which adhesive should I use?
Cement-based or polyurethane, laid as an edge strip with dabs that cover at least 40 % of the EPS and stay under 10 mm thick.
80 mm or 90 mm?
Both go on the open wall. The 90 mm board insulates a little more; the 80 mm keeps the wall face 10 mm further in, which can matter at sills and eaves.
Does the EPS need protecting on site?
Yes. Keep it wrapped and in shade, fix it cool and work behind scaffold covers.
Technical Documentation