Cold Deck Roof

Traditionally flat roofs simply consisted of a structural timber deck with a waterproof covering directly applied to the top of the deck.

Cold deck roof.

Contrasted with the cold deck roof this construction has a much lower risk of condensation as the void will be of a comparable temperature to the roof. The insulation in a warm deck roof is installed immediately below the roof membrane on top of the roof deck usually with a vapour control layer underneath the insulation. Cold deck definition is a stacked pack of playing cards. Where a cold flat roof does incorporate insulation this is.

In the case of a flat roof the roof deck and waterproof membrane are supported on joists the internal ceiling is attached to the underside of the joists and should have a vapour barrier to stop condensation penetrating the internal decor. Guidance advice on warm cold. Ventilation is required for these roofs. A cold flat roof insulation requires more work taking off old boards and replacing them and the roof surface.

Introduction warm cold roofs this guidance offers guidance on the difference benefits between warm and cold roofs. One prepared for surreptitious substitution for the pack in play. Traditional cold deck flat roof. Cold deck with epdm rubber roof.

The 18mm roof grade deck is then fixed on top of the rafters leaving suitable air flow between the insulation and the deck. This design dates back many years and flat roof insulation was somewhat of an afterthought with this type of roof. This system is called warm deck insulation and eradicates the condensation and venting issues associated with the cold deck system. A cold deck roof is where the insulation is placed between the joists rafters or in between the ceiling joists in the case of a pitch roof.

This is known as a cold roof because the roof deck and roof space are close to the external air temperature. A cold roof construction will normally comprise of a structural deck on joists or purlins with a ceiling layer fixed to the bottom of the joists purlins thereby creating an air layer or cavity within. Fortunately these days there is a better form of insulation available for your flat roof. The cold deck is the most common but also the least thermally efficient design of roof insulation.

The solution warm deck insulation.