Warm Flat Roof Joist Construction

Sizes of joists needed for flat roof construction.

Warm flat roof joist construction.

Others would treat even steeper pitches as flat roofs. 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. A roof is considered to be flat when it is of a slope of 1 5 o to the horizontal. Although flat roofs are cheaper to build than pitched roofs they have a shorter life span.

Constructing a warm roof on a new extension with parapet walls i will have surplus amounts of insulation left over and am considering adding this insulation to the underside between the joists to double up the insulation would this install have any negatives. There are two main types of flat roof systems to choose from. This approach uses insulation with no air gap either immediately above or below the roof deck. 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.

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. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. Learn more about warm roof cold roof construction.

So any timber joists that are used need to be strong enough to support this weight. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. Old asbestos roofs are often replaced with flat roofs. Waterproof membrane to prevent water penetrating the structure and interior of the.

Flat roof construction for residential. The reasons for selecting either one will depend on the requirements of the build considering the level of insulation required heat loss and building regulations.