Fig. 6.2 Solid ground floor.
Figure 6.2 illustrates the floor plan of a detached house. The sub-soil is clay, and the floor is uninsulated. First, calculate the perimeter to area ratio:
P = 2 x (10.2 + 6.7) = 33.8 m A = 10.2 x 6.7 - 3.5 x 2.7 = 58.89m2 P/A = 33.8/58.89 = 0.57 m/m2
The U-value is found from Table 6.1, using the column for zero thermal resistance. The Approved Document recommends that the row nearest to the actual P/A value is used; in this case the nearest row to 0.57 is P/A = 0.55. It is not necessary to interpolate between rows because the change in U-value between rows is not large enough to warrant the extra work. The U-value of this floor is therefore:
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