Flat Roof Joist Detail

X 5 8 bolt brass alum.

Flat roof joist detail.

Detail for attachment to metal panel siding or fascia. This demo version is fixed at 1m clear span. Nail to backer block and joist with 2 rows of 10d nails 6 o c. The construction of the flat roof is similar to that of the timber upper floor.

In the warm flat roof construction there is insulation packed into every possible space where air can flow. Downspout strap detail 1 4 dia. On a basic level flat roof construction comes in the form of roofing timbers or joists as they are more commonly known or steels that are laid across two uprights walls in most cases. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls.

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. The full version allows any size. This detail for cmu installation only. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure.

Figure 3 i joist cantilever detail for balconies 1 1 2 x l4 minimum 4 maximum where l is length l of cantilever 2 x 8 min. Continuous ceiling joists or collar ties span from rafter to rafter. The flange material is typically laminated veneer lumber lvl or solid sawn lumber and the web is made with plywood or osb. There is no need for bearing posts under the ridge board which is nonstructural.

1 enter joist details 1 1 span and joist spacing. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. This is the distance between joist centres. Cantilever nails may be used to attach backer block if length of nail is sufficient to allow clinching.

In a typical roof framed with dimension lumber the rafters rest on the exterior wall top plate at the lower end and bear against a ridge board at the top. 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. 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. Usually 400 450 or 600mm but any value can be used up to 610mm max.

Minimum r value of exterior ci determined by total r value of insulated assembly see also.