Roof Joist Construction Details

The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls.

Roof joist construction details.

Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. This will give additional stability to the roof structure. Secure each tile with two large head roofing nails. End bearing in hanger supported by i joist s 44kb.

End bearing with rim joist. Double the tiles at eaves and project them 1 inch over the rear edge of gutters. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. End bearing with rim board.

I joists in floor and roof applications. End bearing in hanger on a top plate. Intermediate bearing with blocking panels. In addition to floor and roof framing details this guide includes recommendations for cantilevers and placement of web holes.

End bearing in hanger supported by a beam. Lay 10 or 12 inch tiles with 1 inch head lap on the sides of dormers. For additional stability you can also use steel joists that are built into one or both of the walls. The construction of the flat roof is similar to that of the timber upper floor.

In the uk a concrete tiled roof would normally have rafters at 600 mm 24 in centers roof battens at 300 mm 12 in centers and ceiling joists at 400 mm 16 in centers. The united states still uses imperial units of measurement and framing members are typically spaced sixteen or twenty four inches apart. Good installation begins with specification of the correct joist for the application.