Flat Roof Framing Detail

Although flat roofs are cheaper to build than pitched roofs they have a shorter life span.

Flat roof framing detail.

A flat roof has a slope of 1 8 per foot to 2 12. 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. The rise or height of the roof at its peak is the altitude of the triangle. Cad details document name pdf dwg download all cad construction details 37 1 mb 3 4 mb mc01 identification of roof areas 694 kb 167 kb mc01a single layer underlayment 678 kb 302 kb mc01b double layer underlayment 711 kb 322 kb mc02 vent pipe flashing 626 kb 349 kb mc03 valley.

And the line length measurement from the roof peak to the building wall is the hypotenuse. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. Some roofs actually slope in several directions ensuring optimal water runoff. You can do this with a foam layer that exactly fits your roof.

But now flat roofs often are constructed with fewer layers because of improved waterproofing technology. So any timber joists that are used need to be strong enough to support this weight. The framing of a basic gable roof is based on a right angle triangle and the various roof framing components fit the triangle. Old asbestos roofs are often replaced with flat roofs.

Of course you don t need to live in a modern house to deal with a flat roof. This could mean flat roofs may not raise the same red flags they used to. Details for conventional wood frame construction the first approach to achieving a strong durable struc ture involving economical use of materials is to follow a. Flat roof construction for residential.

Think of a flattened hip roof. Some observers suggest it s harder to replace a flat roof than a traditional pitched shingle roof because of the labor required to remove its layers especially on older flat roofs. Sizes of joists needed for flat roof construction. Flat roofs are always built at a slight incline at least 1 8 inch per foot.

It is not ideal for snow or heavy rain but modern materials and proper drainage have helped. If you build a flat roof try to have it slope in multiple directions to drains or gutters. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. When framing a flat roof you will need to create a slight incline.

The run or half the building span is the base of the triangle.