Cold Deck Flat Roof Detail

In terms of the thermal design of a flat roof what are the options and the best practices of flat roof build ups.

Cold deck flat roof detail.

Guidance advice on. Cold deck roof 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. The recognised flat roof build ups for best design practices are. Details both in 2d and 3d to give a clear understanding.

When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. The insulation is placed below the waterproof covering and is either mechanically fixed or bitumen bonded on to the top of the deck. Others would treat even steeper pitches as flat roofs. Ventilation is required for these roofs.

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 sandwich warm deck roof is the most common type of flat roof. Inverted warm deck roof. The insulation boards in an inverted warm deck are laid over the structural deck and the waterproof covering.

This video shows the key features of a flat roof cold deck construction and how to draw the details to a scale of 1 10. This cold deck construction is considered problematic in the humid temperate climate of the uk where the effective ventilation of restricted roof voids may be impractical particularly in sheltered built up areas. Hopefully this video will help explain the difference between cold flat roof construction and warm flat roof construction this videos show detailed drawings. Similar to the pitched roof a flat roof can be insulated as a cold or a warm deck.

Flat roof details and information relating to insulating a flat roof. The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal however some in the industry would consider up to 15 o as their definition of a flat roof. Introduction warm cold roofs this guidance offers guidance on the difference benefits between warm and cold roofs. The position of the insulation dictates which type it is.

The epdm rubber roof membrane is then installed using the contact adhesive onto the deck. In a cold roof construction the sarnafil membrane is installed directly to the structural decking usually timber with firrings to fall. This is known as a cold roof because the roof deck and roof space are close to the external air temperature.