Flat Roof Cold Deck Construction

The insulation material is placed immediately above the ceiling between the rafters.

Flat roof cold deck construction.

Others would treat even steeper pitches as flat roofs. There is no need for additional ventilation. A cold deck is constructed as follows. Thickness varies according to the manufacturer s specifications.

Plywood the insulation is fixed directly on top often with. Warm cold and inverted. In a cold weather such roofs are inherently prone to condensation which can cause material decay and deterioration. Flat roof design guide.

Flat roof u value 0 18 w m2k 2 warm deck flat roof the type of insulation for this is usually of a rigid type and the thickness will vary depending on the manufacturer s specifications. It is universally recommended that cold deck flat roof construction should be avoided. 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. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off.

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. 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. 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.

This arrangement allows the deck to become cold. Where the existing roof deck is in satisfactory condition and of a suitable material e g. Where the insulation is placed above the structural deck warm deck and either above or below the waterproofing. 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.