Pitched Roofs
Pitched roofs can be insulated at ceiling level or at rafter line: applying insulation at rafter line brings all the building volume within the insulation envelope (Figure 56).
By insulating at rafter line:
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the insulated space enclosed by the building envelope is substantially increased without altering the structural design; the additional space can be used as part of the initial design or converted for use at a later date.
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the whole of the building fabric is kept at a similar temperature, thereby reducing the risk of condensation on structural members.
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thermally induced movement is reduced because the roof structure is not subject to extremes of temperature.
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a board insulated roof offers greatly improved resistance to wind driven rain and fine snow.
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pipes, tanks and services in the loft space are protected from freezing temperatures.
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pipes and wiring at ceiling level are not hidden by insulation.
Insulating warm roofs
Warm roofs may be formed with the insulation installed part above and part between the rafters (Figure 57).
Warm pitched roof constructions are not covered by any British Standard, although some guidance is contained in BS 5250, BS 5534 and BRE document ’Thermal insulation: avoiding risks’
STYROFOAM™ Solution
The STYROFOAM solution for insulating pitched roofs at rafter line is ROOFMATE RL-X, a tongue and grooved STYROFOAM board (Figure 57).
