43 ETFE cushions
A rooflight or glazed roof from the tool's Fabric roofs group. With etfe cushion, three layers in a aluminium, no thermal break frame it has an overall U-value of about 2.16 W/m²K.
- U-value
- 2.16W/m²K
- Glass or infill
- ETFE cushion, three layers
- Frame
- Aluminium, no thermal break
- Frame share
- 4% of area
Against the Building Regulations
| New home in | U-value limit | This build-up, 2.16 |
|---|---|---|
| England | 2.20 W/m²K | Meets it |
| Wales | 2.20 W/m²K | Meets it |
| Scotland | 1.40 W/m²K | Misses by 0.76 |
These are the limits for a single element in a new home. In England a new home usually needs better figures to pass the whole-house target. All UK U-value limits.
How the U-value is made up
For glazed systems the U-value combines the glass or infill (centre U-value 2.00 W/m²K), the frame (U-value 5.90 W/m²K, 4% of the area) and the heat lost at the glass edges, following BS EN ISO 12631. Frames and edges usually make the overall figure noticeably worse than the glass alone.
Other fabric roofs
Figures come from the Build-up Atlas's own calculation, with generalised values for typical products, for an England new home with default settings. They are indicative, for design and teaching: check the manufacturer's declared values and the current regulations for your project. Rules and standards last checked 21 October 2026.