Flat Roof Framing Detail

A roof is considered to be flat when it is of a slope of 1 5 o to the horizontal.

Flat roof framing detail.

The framing of a basic gable roof is based on a right angle triangle and the various roof framing components fit the triangle. Some roofs actually slope in several directions ensuring optimal water runoff. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. This will help you create a flat roof framing plan.

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. 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. Although flat roofs are cheaper to build than pitched roofs they have a shorter life span. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc.

When framing a flat roof you will need to create a slight incline. Old asbestos roofs are often replaced with flat roofs. And the line length measurement from the roof peak to the building wall is the hypotenuse. The rise or height of the roof at its peak is the altitude of the triangle.

So any timber joists that are used need to be strong enough to support this weight. Flat roofs are always built at a slight incline at least 1 8 inch per foot. A flat roof has a slope of 1 8 per foot to 2 12. Flat roofs are hard to replace.

Sizes of joists needed for flat roof construction. You can do this with a foam layer that exactly fits your roof. 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.

It is not ideal for snow or heavy rain but modern materials and proper drainage have helped. This could mean flat roofs may not raise the same red flags they used to. 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. If you build a flat roof try to have it slope in multiple directions to drains or gutters.

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