37


Specifying external wall insulation


By Dr Jeremy Richings, technical director of PermaRock Products Ltd T


he use of external wall insulation (EWI) is now commonplace for new buildings and for the refur- bishment of existing buildings, both residential and


non-residential. By providing the insulation layer to the outside face of the


primary structure the building designer can overcome many of the problems associated with cavity insulation, in particular that of thermal bridging (cold bridging), which occurs whenever a material of higher thermal conductivity passes through an


insulation layer or wherever there is a break in the insulation continuity, a frequent problem encountered in both traditional cavity walls and in frame constructions. In the former, insulation continuity might be interrupted at


heads and jambs of windows as a result of the building design, and thermal continuity might be compromised because of poor installation resulting in gaps in the insulation layer. Gaps between insulation boards inside a cavity wall are not visible and are not readily rectified, so such cold bridges can go


Continued overleaf... respond online at www.architectsdatafile.co.uk


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44