Choose the thickness by how much heat you need to keep in and how far the panel must span. Thicker panels give a lower U-value and longer spans: 0.71 W/m2K at 30 mm, 0.48 at 40 mm and 0.25 at 80 mm.
What the U-value tells you
The U-value is the rate of heat loss through the panel. A lower number means less heat escapes. Our U-values are calculated to EN 14509, the standard for factory-made double skin metal faced insulating sandwich panels. The core is rigid PIR foam at about 40 kg per cubic metre, with a thermal conductivity of 0.023 W/mK. The core is bonded between steel sheets, which gives the panel strong spanning capability.
The options
- 30 mm PIR or PUR: U-value 0.71 W/m2K and 7.42 kg per square metre. The PUR version has one steel sheet on top and a foil underside.
- 40 mm PIR: U-value 0.48 W/m2K and 7.4 kg per square metre.
- 80 mm PIR: U-value 0.25 W/m2K and 9.0 kg per square metre.
Span and load
The product pages for 40 mm and 80 mm carry load and span tables for wind and snow pressure and for wind suction. As an example, at 1.00 kN/m2 pressure a single span can be 2.65 m at 40 mm and 4.06 m at 80 mm. Always check both pressure and suction for your site, as the tables advise. A thicker panel can span further between purlins, which can mean fewer supports.
Fire performance
The 40 mm and 80 mm PIR panels are classed B-s2,d0 to EN 13501-1, with an external fire performance of BROOF (t4) to EN 13501-5.
Fixings, pitch and finish
The fixing length rises with the panel: 6.5 mm fixings are 100 mm long for 30 mm panels and 150 mm long for 80 mm panels. The minimum roof pitch is 4 degrees on every panel. The panels have a 1000 mm cover width, with ribs 30 mm deep at 333 mm centres.
Anthracite is available in 30 mm, 40 mm and 80 mm PIR. Dark/Moss Green is available in 30 mm PIR only.
Lengths and delivery
Cutback panels are stocked in 3.075 m to 7.075 m lengths with a 75 mm cutback. Panels with no cutback come in 3 m to 7 m lengths. Briarwood makes the PIR and PUR panels at its own plant in Italy. They are delivered by lorry to the kerbside in an estimated 6 to 10 working days, to England, Wales and mainland Scotland, and unloading assistance is required.
Choosing in practice
- If you want a balance of insulation and a lighter panel, look at 30 mm or 40 mm.
- If heat retention or the longest spans matter most, choose 80 mm.
See the full range: insulated roof panels. For help choosing, call 01278 228670 or email [email protected].