Roof Joist Construction Details

Joist is a term used in construction for load bearing planks that run horizontally or nearly to horizontally to ground.

Roof joist construction details.

I joists in floor and roof applications. The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. They differ considerably from the conventional gabled roofs in shape and construction. Intermediate bearing with blocking panels.

Refer to the details. They are ideal for long spans including continuous spans over intermediate supports. End bearing in hanger supported by i joist s 44kb. Good installation begins with specification of the correct joist for the application.

In addition to floor and roof framing details this guide includes recommendations for cantilevers and placement of web holes. Secure each tile with two large head roofing nails. Two nails are used for widths up to 8 inches. Double the tiles at eaves and project them 1 inch over the rear edge of gutters.

In double coursing the under course is attached to wood sheathing with three nails or staples. Lay all tiles within 1 foot of hips ridges and abutting vertical surfaces in roofer s cement. With single course applications nails are driven one inch above the butt line of the succeeding course. So the only reason these planks are called roofing joists is because they run horizontally or nearly horizontally to the ground.

This will give additional stability to the roof structure. The construction of the flat roof is similar to that of the timber upper floor. For additional stability you can also use steel joists that are built into one or both of the walls. Include roof pitch roof geometry slope length and climatic factors such as heavy snowfall or rainfall.

Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. Whenever possible begin trim installation at the downwind end of the roof farthest away from the source of prevailing winds to al low flashing laps to face away from wind driven rain. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. Lay 10 or 12 inch tiles with 1 inch head lap on the sides of dormers.

End bearing in hanger on a top plate. End bearing in hanger supported by a beam. I joists are used extensively in residential floor and roof framing. Mono pitched roofs are also known by the names of skillion roofs shed roofs pent roof and lean to roof.

Because i joists are straight and true it s easier for builders to avoid crowning and maintain a level framing surface. End bearing with rim joist. End bearing with rim board. For wider shingles and shakes three nails are used.