Description
These 30mm polystyrene sheets are grey graphite polystyrene, 1000 × 500 mm, for walls that are insulated from outside and then rendered. Thirty millimetres is the step up from the thinnest polystyrene in the range: deep enough for wider reveals, lintel faces and shallow returns, and still slim enough to keep a window frame from disappearing behind the insulation. The sheets belong to the Renders World graphite board range, eleven thicknesses from 10 mm to 200 mm.
Each of the 30mm polystyrene sheets covers half a square metre. Declared thermal conductivity: ≤ 0.031 W/mK.
30mm Polystyrene Sheets: What You Get
A single sheet measures 1000 mm by 500 mm and is 30 mm deep. The polystyrene has graphite blended in at the factory, which gives it the grey colour and lets it insulate better than plain white polystyrene of the same depth.
| 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 polystyrene on its own. A rendered façade is assessed as a complete system, so the fire classification of the finished wall comes from the system specification, not from the polystyrene. How 30 mm affects the heat loss of a particular wall is shown step by step in the U-value and insulation thickness guide.
Made for Walls and Openings
These sheets have one job, and it is on the wall:
- a façade board, cut to 1000 × 500 mm to match the thicker wall boards in the same system;
- meant for vertical faces that are bonded, meshed and rendered, not for walking on.
The foundations, the plinth and any work below ground take a different board. Renders World stocks a 30 mm foundation board for exactly those places, as a separate product.
Why 30 mm Works Around Openings
- Room for a deeper reveal. Where a jamb allows more than 20 mm, the extra 10 mm of graphite polystyrene keeps more heat in around the opening.
- Less to cut away. Strips for jambs, heads and sills come from polystyrene that already matches the reveal depth, so there is less trimming on the scaffold.
- Same face as the main wall. The 1000 × 500 mm format is shared from 20 mm up, so joints between the reveal lining and the wall boards line up.
- Accurate to the millimetre. Thickness is held to ± 1 mm and flatness to 5 mm, which keeps a narrow reveal face true for the base coat.
- Firm under the mesh. Bending and tensile strength are each at least 100 kPa.
- Stays put. In normal conditions the polystyrene changes size by no more than 0.2 %.
- Your choice of adhesive. It takes either a cement-based or a polyurethane adhesive.
Where a 30mm Board Goes
- Window and door reveals deeper than a 20 mm lining needs.
- Lintel faces and heads, where the frame leaves room for 30 mm.
- Loggias and balconies, on their shallow side walls and soffits.
- Expansion joints, as the joint filling.
- Stud walls and cavity walls, on the outer face of the studs or in the enclosed or ventilated slot.
The polystyrene sheets bond to concrete, to cement and cement-lime plaster, to bare brick, block and hollow block in ceramic or silicate, and to aerated concrete.
How Many 30mm Polystyrene Sheets to Order
Order 30mm polystyrene sheets two to every square metre. A full pack holds 20 sheets and covers 10.00 m².
- Twelve windows with reveals of about 0.75 m² each give 9 m², so 9 ÷ 0.5 = 18 sheets, a little under one pack.
- Reveal strips are narrow, so work out how many strips one sheet gives at your reveal depth and order whole sheets from that count.
- Where the main wall is a thicker board, list the 30mm polystyrene sheets as a separate line on the order.
Fitting the Board
Use a cement-based or polyurethane adhesive from the adhesives and basecoats for insulation boards. The background has to be free of frost, load-bearing, even and sound, and clean of dust, dirt, lime, oil, grease, wax and old emulsion or oil paint.
- Get the background right. Very absorbent surfaces, weak cement or cement-lime plaster and rough aerated or cinder block get a coat of Uni-Grunt priming emulsion. Larger hollows and gaps are filled first with ZW 330 mortar or Plastering Mix M, which appears in the shop as One Coat Dash Cover.
- Apply the adhesive. Run a continuous strip at least 3 cm wide around the edge of the polystyrene and add 6 to 8 dabs, 8 to 12 cm across, inside it. That should cover at least 40 % of the polystyrene, and 60 % once it is pressed on.
- Press it straight on. Keep no more than 10 mm of adhesive behind the polystyrene. On a smooth, even surface the adhesive can be combed over the whole back of the polystyrene with a notched trowel instead, finishing at 2 to 5 mm.
- Sand and dust. Before the base coat the face must be frost-free, flat, clean and firm. Sanding graphite polystyrene and removing the dust is recommended.
Next 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
Graphite sheets must not go on the wall warm, so 30mm polystyrene sheets need a little care on site:
- Cool sheets only. Do not fix polystyrene that has heated up, and keep it shaded while the adhesive takes its first set; heat can make the adhesive let go.
- Packs in the shade. Leave the sheets wrapped and out of direct sunlight, which can bend them.
- Sheeted scaffold. Work behind scaffold covers and stop when it snows, rains or blows hard.
A face left uncovered for weeks, especially in strong UV, can turn yellowish; sand that layer off before the base coat. Acetone, nitro thinners, benzene and similar solvents eat into polystyrene and must be kept away.
If you doubt the wall's strength, bond 8 to 10 polystyrene cubes of 10 × 10 cm across it and pull them after 3 days. A cube that tears through its own middle shows a wall that holds; one that comes away with adhesive or a skin of the wall shows one that does not, and the insulation design has to deal with it.
30mm Among the Other Thicknesses
From 20 mm upwards all the polystyrene in the range shares one 1000 × 500 mm face:
| Thickness | Sheets per m² | Full pack |
|---|---|---|
| 10 mm | 2 | order by the sheet |
| 20 mm | 2 | 30 sheets, 15.00 m² |
| 30 mm (this board) | 2 | 20 sheets, 10.00 m² |
| 50 mm | 2 | 12 sheets, 6.00 m² |
| 80 mm | 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 |
A common pairing is a thick board on the open wall with 30mm polystyrene sheets lining the deeper reveals, and the 20 mm sheet where the frame leaves less room.
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 × 30 mm. One sheet covers 0.5 m², so two cover a square metre.
How many sheets are in a pack?
20 sheets, enough for 10.00 m².
Can I use it for floor insulation?
No. It is a wall board for façades and openings. Floors need a board built for floor loads, and foundations or the plinth take the 30 mm foundation board.
What is its thermal conductivity?
λD ≤ 0.031 W/mK. The U-value is calculated for the whole wall, layer by layer.
Which adhesive should I use?
A cement-based or polyurethane adhesive, laid as an edge strip with dabs so it covers at least 40 % of the polystyrene and stays under 10 mm thick.
20 mm or 30 mm for my reveals?
Measure the gap between the frame and the edge of the reveal. Where 30 mm fits without covering the frame, it insulates better; where it does not, use the 20 mm sheet.
How do I store the sheets before fixing?
Flat, wrapped and out of the sun and rain. Let warm polystyrene cool before it goes on the wall.
Technical Documentation