Cold Flat Roof Design Detail

A roof is defined in bs 6229 as a flat roof if it has a pitch of 10 degrees or less.

Cold flat roof design detail.

Warm cold and inverted. The major difference between the warm flat roof and the cold flat roof has to do with the air flow between the roofing timbers known as joists that help to hold up the roof. It must provide adequate protection against the elements keeping the buildings structure and interior dry. Compact unvented roof assembly r value increased to r 50 in very cold climate zones to control ice damming.

Hopefully this video will help explain the difference between cold flat roof construction and warm flat roof construction this videos show detailed drawings. A flat roof must be strong durable and stable throughout its lifetime. The building regulations in the uk provide guidance on roof design. Basically there are two options to choose from when insulating a flat roof.

Optimum roof assembly design to enclose pool. Installing a warm roof can be extremely straight forward and simple to do. Flat roof types. Flat roof design guide.

Details both in 2d and 3d to give a clear understanding. A cold roof system sees the insulation placed immediately above the ceiling between the joists with ventilation space above the insulation. There are three recognised designs of flat roof construction. This arrangement allows the deck to become cold.

In a cold weather such roofs are inherently prone to condensation which can cause material decay and deterioration. Cold roof construction requires that a suitable ventilated air space exists above the insulation layer within which the air is constantly mobile being replenished by fresh incoming air whilst the air resident within the void space is being expelled via a natural vent action at another point. In cold climate zones the minimum total r value for the entire unvented roof assembly should be r 40. 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 very cold climate zones this minimum r value should be increased to r 50. A cold roof is roof in which the thermal insulation layer is located between the ceiling joists meaning that everything above the insulation such as the rafters and any roof space will be colder than the living space below it. Flat roof details and information relating to insulating a flat roof. There are design differences for each type.

When we talk about a warm roof vs a cold roof what we re really talking about is the insulation of the flat roof.