Summary

Many flat-roofed buildings often lack sufficient insulation, leading to greater heat loss compared to pitched roofs. Insulating a flat roof is costly and is best addressed during roof replacement, which is now required by building regulations. Typically, a phenolic insulation board like Kingspan or Celotex is used to lay in between the roof timbers (cold deck), or alternatively the insulation board is laid straight on top of the existing flat roof (warm deck) and a whole roof covering is fitted over the top of the system.

Various flat roof coverings, such as EDPM rubber, fibreglass, and felt, can be selected based on cost, roof size, suitability, and contractor expertise.