Garage Flat Roof Joist Construction

Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof.

Garage flat roof joist construction.

The starting point involves laying roofing joists across the two upright items which in most cases will be the walls of the structure. A flat roof garage built with joists span the gap between two walls. By way of metal flat roof joist hangers. There are key differences between constructing a flat roof compared to a pitched roof and it s important to understand the basic criteria.

Sizes of joists needed for flat roof construction. 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. Ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice. In the warm flat roof construction there is insulation packed into every possible space where air can flow.

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. Old asbestos roofs are often replaced with flat roofs. A cavity closer should be provided to the top of the walls to prevent fire spread and to stop damp air entering the roof space. Of course you don t need to live in a modern house to deal with a flat roof.

Yet for historic modern style buildings like this old house s cambridge tv project flat roofs are at the core of the architecture meant to reflect the broad horizontal lines of the natural landscape. Where a new flat roof abuts an existing external wall the joists can be hung on metal joist hangers which are fixed to a horizontal timber plate wall bolted to the wall. So any timber joists that are used need to be strong enough to support this weight. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc.

This article covers all manner of flat roofing venting methods and details on how to build a flat garage roof and how to frame a flat roof and also encompasses flat roofs roof decking roof coverings including flat roof felt how to prevent leaks at abutments timber flat roof construction details and parapets and common. Maximum clear span of flat roof joists in metres for sc3 timber spacing between joists size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42. I joist wood beams shaped like the capital letter i add strength to the garage and roof top.