17 Small precast or GRC cladding panels
An external wall from the tool's Concrete walls group. With the layers below it has a U-value of 0.20 W/m²K, is 350.5 mm thick, and has about 62 kgCO₂e/m² of embodied carbon.
- U-value
- 0.20W/m²K
- Overall thickness
- 350.5mm
- Embodied carbon
- 62kgCO₂e/m²
- Fire
- Worst class E
Against the Building Regulations
| New home in | U-value limit | This build-up, 0.20 |
|---|---|---|
| England | 0.26 W/m²K | Meets it |
| Wales | 0.18 W/m²K | Misses by 0.02 |
| Scotland | 0.17 W/m²K | Misses by 0.03 |
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, about 0.18 for walls. All UK U-value limits.
Section, drawn to scale
Layers, outside to inside
| # | Layer | mm | λ, W/mK | R, m²K/W | kgCO₂e/m² | Fire class |
|---|---|---|---|---|---|---|
| 1 | GRC cladding panel outside the ventilated cavity: not counted | 20 | 0.9 | – | 16.0 | A1 |
| 2 | Ventilated cavity behind cladding outside the ventilated cavity: not counted | 40 | – | – | 0 | – |
| 3 | PIR board | 120 | 0.022 | 5.455 | 13.4 | E |
| 4 | Bitumen felt or roofing membrane | 3 | 0.23 | 0.013 | 1.4 | E |
| 5 | Dense concrete block | 140 | 1.13 | 0.124 | 28.0 | A1 |
| 6 | Unventilated cavity or dab gap | 15 | – | 0.171 | 0 | – |
| 7 | Plasterboard | 12.5 | 0.21 | 0.060 | 3.5 | A2-s1,d0 |
| Total, with surface resistances | 350.5 | 6.082 | 62.3 |
U-value worked out to BS EN ISO 6946 from the total resistance, plus 0.040 W/m²K of corrections for fixings, gaps or brackets. Carbon is stages A1 to A3 for the layers.
Moisture and rain
Fails: condensate builds up year on year Up to 0 g/m² at , with some left after 12 months. Surface factor 0.95 (needs over 0.71 and at least 0.75).
Rain: Zone 2 of max 4 for exposure zone 2 (moderate).
Other concrete walls
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.