Concrete slab, PIR and screed
A solid ground floor from the tool's Typical UK floors group. With the layers below it has a U-value of 0.15 W/m²K, is 315 mm thick, and has about 103 kgCO₂e/m² of embodied carbon.
- U-value
- 0.15W/m²K
- Overall thickness
- 315mm
- Embodied carbon
- 103kgCO₂e/m²
- Fire
- Worst class E
Against the Building Regulations
| New home in | U-value limit | This build-up, 0.15 |
|---|---|---|
| England | 0.18 W/m²K | Meets it |
| Wales | 0.15 W/m²K | Meets it |
| Scotland | 0.15 W/m²K | Meets it |
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.
Section, drawn to scale
Layers, outside to inside
| # | Layer | mm | λ, W/mK | R, m²K/W | kgCO₂e/m² | Fire class |
|---|---|---|---|---|---|---|
| 1 | Reinforced concrete | 150 | 2.3 | 0.065 | 64.8 | A1 |
| 2 | PIR board | 100 | 0.022 | 4.545 | 11.1 | E |
| 3 | Sand-cement screed | 65 | 1.15 | 0.057 | 27.3 | A1 |
| Total, with surface resistances | 315 | 4.877 | 103.2 |
U-value worked out to BS EN ISO 6946 from the total resistance. Carbon is stages A1 to A3 for the layers.
Moisture and rain
Not checked Ground-bearing floors need 2 m of soil in the model and ground temperatures (BS 5250 13.2.2.3), which this tool does not do.
Rain: Not checked for exposure zone 2 (moderate).
Other typical UK floors
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.