Flat Roof Insulation

Insulation boards installed as part of a flat roof build-up to achieve the required U-value (typically 0.18 W/m²K under Part L). In a warm roof the insulation is above the structural deck; in an inverted roof it is above the waterproofing membrane. PIR (Celotex/Kingspan) or EPS boards at 150–200 mm depth are typical. The insulation thickness must also prevent condensation risk within the build-up.