Flooring U-values	Semi Detached House
Perimeter Length to Area Ratio U-Value W/m²K 1:1 0.46 0:9 0.45 0:8 0.44 0:7 0.42 0:6 0.4 0:5 0.38 0:4 0.35 0:3 0.3 0:2 0.26 0:1 0.17

The heat loss in a floor is greater at the exposed perimeter edge of the floor. To calculate the U-Value, the exposed perimeter edge to area ratio needs to be worked out e.g. - a 100m² area, semi-detached house with 3 external walls of 10m each has a perimeter edge to area ratio of 0.3 (i.e. 30m ÷ 100m²=0.3) which, using Foil-Tec Single, gives a U-Value of 0.3 W/m²K.