Timber Cold Flat Roof Construction

The major difference between the warm flat roof and the cold flat roof has to do with the air flow between the roofing timbers known as joists that help to hold up the roof.

Timber cold flat roof construction.

One of the most essential considerations in a cold deck flat roof construction is the requirement for adequate ventilation in the form of a ventilated cavity of at least 50mm between the underside of the timber deck and the roof insulation below. Sizes of joists needed for flat roof construction. In a cold roof construction the sarnafil membrane is installed directly to the structural decking usually timber with firrings to fall. Old asbestos roofs are often replaced with flat roofs.

This is used for refurbishment e g. Hopefully this video will help explain the difference between cold flat roof construction and warm flat roof construction this videos show detailed drawings. There must be an adequate void minimum 50mm between the deck and the insulation traditionally mineral wool to allow free movement of air and to prevent moisture vapour being transmitted from the building outwards where it could condensate in the roof. The insulation is below the deck but above the plasterboard.

As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. A cold flat roof is one where the insulation is between or between and below the roof joists. This ventilation is necessary to prevent condensation from forming below the roof deck which can.