U-Value Calculator

Build up wall, floor or roof layers and calculate the U-value. Check compliance with UK Part L building regulations.

Element Type

Outside → Inside

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Total thickness 0 mm

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U-Value

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W/m²K

Total R

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m²K/W

Part L limit

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W/m²K

Margin

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W/m²K

External wall (new) 0.26 W/m²K

External wall (refurb) 0.30 W/m²K

Roof (new) 0.16 W/m²K

Roof (refurb) 0.18 W/m²K

Ground floor (new) 0.18 W/m²K

Ground floor (refurb) 0.22 W/m²K

Party wall 0.20 W/m²K

Mineral wool 0.033–0.044

PIR rigid board 0.020–0.026

EPS 0.030–0.040

Dense brick 0.77

Concrete block 0.19–1.13

Timber 0.13

Plasterboard 0.21

Glass 1.05