Warm Flat Roof Joist Construction

In the warm flat roof construction there is insulation packed into every possible space where air can flow.

Warm flat roof joist construction.

This video shows detailed drawing. If you put insulation under the decking and between the joists you lower the temperature of the decking and lower the due point thus bringing it closer to the danger point of being in the building. A flat roof usually consists of the following. Sizes of joists needed for flat roof construction.

Flat roof construction for residential. Old asbestos roofs are often replaced with flat roofs. There are two main types of flat roof systems to choose from. A roof is considered to be flat when it is of a slope of 1 5 o to the horizontal.

So any timber joists that are used need to be strong enough to support this weight. Flat roof with no permanent access and altitude not exceeding 100m 0 75 kn m udl 0 9 kn point load most areas exceeding 100m but not exceeding 200m excluding parts of scotland pennines north east england refer to bs 6399 3 1 kn m udl 0 9 kn point load. Waterproof membrane to prevent water penetrating the structure and interior of the. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off.

As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. This is placed over the roof joists and a board normally external ply is laid on top. 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. Hopefully this video will help explain the difference between warm flat roof construction and cold flat roof construction.

Although flat roofs are cheaper to build than pitched roofs they have a shorter life span. Good question theoretically when building a warm roof the vaper control layer goes on the warm side of the insulation. This approach uses insulation with no air gap either immediately above or below the roof deck. 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.