Flat Roof Cold Deck Construction

Building regulations state that a ventilation gap of at least 50mm must be in place between the insulation and the underside of the flat roof deck.

Flat roof cold deck construction.

There is no need for additional ventilation. This is placed over the roof joists and a board normally external ply is laid on top. 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. Less thermally efficient than a warm roof construction cold roof construction remains the most common form of construction for existing flat roofs.

There are three recognised designs of flat roof construction. Warm cold and inverted. In a cold weather such roofs are inherently prone to condensation which can cause material decay and deterioration. Thickness varies according to the manufacturer s specifications.

Plywood the insulation is fixed directly on top often with. This arrangement allows the deck to become cold. Where the insulation is placed above the structural deck warm deck and either above or below the waterproofing. For both a warm and cold flat roof a vapour control layer must be installed.

Flat roof design guide. Others would treat even steeper pitches as flat roofs. Ashford building services can quickly and economically convert any cold deck flat roof to a warm deck insulated flat roof particularly where problems have been tackled sooner rather than later. In the case of cold roofs the residential flat roofs have the waterproof placed directly on the deck and any insulation would be placed above the ceiling.

In the case of a flat roof insulation is usually in the form of either a rigid board above the deck or a fibrous quilt immediately above the ceiling depending on the type of roof construction. A cold deck is constructed as follows. It is universally recommended that cold deck flat roof construction should be avoided. The insulation material is placed immediately above the ceiling between the rafters.