The thickness of roof insulation is determined by the U-Value requirements. It is common to use the same thickness of insulation between the rafters as you have used above the rafters. The table below is based on a typical warm roof construction with insulation above and between the rafters. To calculate U-Values specific to a different warm roof design, use our free online U-Value calculator.
|Insulation above rafters (mm)|
|Insulation between rafters||60||70||80||90||100||110||120||125|
|Thickness (mm)||U-value (W/m2K)|
U-value results above based upon pitched roof construction shown:
150mm deep rafters @400mm centres; Mannok Therm Roof / MR between rafters; Mannok Therm Roof / MR above rafters; vapour open underlay; 50mm cavity formed by counterbattens; large format concrete tiles. Calculations performed to BS EN ISO 6946, taking account of repeating thermal bridges.
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