Flat Roof Cold Deck Construction

Where the existing roof deck is in satisfactory condition and of a suitable material e g.

Flat roof cold deck construction.

Flat roof design guide. Warm cold and inverted. For both a warm and cold flat roof a vapour control layer must be installed. 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.

Thickness varies according to the manufacturer s specifications. This arrangement allows the deck to become cold. Less thermally efficient than a warm roof construction cold roof construction remains the most common form of construction for existing flat roofs. Plywood the insulation is fixed directly on top often with.

As the insulation is not required to take any loads quilts and other loose fill materials can be used as well as rigid insulation. There is no need for additional ventilation. In a cold weather such roofs are inherently prone to condensation which can cause material decay and deterioration. It is universally recommended that cold deck flat roof construction should be avoided.

Although not recommended today and actually banned in scotland until recently cold flat roofs were fairly common. 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. Where the insulation is placed above the structural deck warm deck and either above or below the waterproofing. There are three recognised designs of flat roof construction.

The insulation material is placed immediately above the ceiling between the rafters. In a cold roof the thermal insulation is laid between the joists below the structural deck. 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. A cold deck is constructed as follows.