Amendment No. 1 to BR497 2nd Edition 2016
1. At Page 37, the material properties associated with the diagram should be as follows to obtain the quoted result: 360mm flat roof mineral insulation (0.040 W/mK), 50mm sloping roof rigid insulation (0.022 W/mK), 175mm sloping roof rigid insulation (0.027 W/mK).
2. At Page 40, the material dimensions on the diagram should be as follows to obtain the quoted result: the cavity (low-e) behind the plasterboard should be 25mm in all cases. The inner rigid foil-faced insulation (0.022 W/mK) behind the 25mm cavity should be 37.5mm. (The rigid insulation in the centre of the wall is correct at 75mm). The calculation at Step 5 should quote Q2D as 11.3197 W/m.
3. At Page 41 Table B5 the value of Rsi given for downward heat flow is incorrect. The value of 0.10 m²K/W should be 0.17 m²K/W. This is also the case at Page 42 Table B6 and at Page 44 Table B7.
Notes & clarifications:
1. At Page 44 Step 4 the equation is not as given on Page 23 for a suspended floor.
For consistency, the equation used here in Example 7 should have been the same as given on Page 23. Note that either equation will provide the same result for psi‑value since the heat flow to be subtracted from the total heat flow will calculate to be the same.
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