Flat Roof Cold Deck Construction

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.

Flat roof cold deck construction. 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. Others would treat even steeper pitches as flat roofs. 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. Flat roof design guide.

It is universally recommended that cold deck flat roof construction should be avoided. Plywood the insulation is fixed directly on top often with. Where the insulation is placed above the structural deck warm deck and either above or below the waterproofing. A cold deck is constructed as follows.

This arrangement allows the deck to become cold. There are three recognised designs of flat roof construction. Where the existing roof deck is in satisfactory condition and of a suitable material e g. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off.

There is no need for additional ventilation. Thickness varies according to the manufacturer s specifications. 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. Warm cold and inverted.

Less thermally efficient than a warm roof construction cold roof construction remains the most common form of construction for existing flat roofs. In a cold weather such roofs are inherently prone to condensation which can cause material decay and deterioration. For both a warm and cold flat roof a vapour control layer must be installed. This is placed over the roof joists and a board normally external ply is laid on top.