Timber Cold Flat Roof Construction

As you may imagine there is a fair amount of weight involved here in terms of boards felt etc.

Timber cold flat roof construction.

A cold flat roof is one where the insulation is between or between and below the roof joists. This is used for refurbishment e g. In the warm flat roof construction there is insulation packed into every possible space where air can flow. 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.

Hopefully this video will help explain the difference between cold flat roof construction and warm flat roof construction this videos show detailed drawings. Refurbishing an existing timber joisted flat roof which has no insulation. In a cold roof construction the sarnafil membrane is installed directly to the structural decking usually timber with firrings to fall. This ventilation is necessary to prevent condensation from forming below the roof deck which can.

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. So any timber joists that are used need to be strong enough to support this weight.