Flat Roof Framing Design

There are two types of flat roof system and they differ according to whether the insulation is above or below the structural roof deck.

Flat roof framing design. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. A flat roof has a slope of 1 8 per foot to 2 12. You can do this with a foam layer that exactly fits your roof.

It is not ideal for snow or heavy rain but modern materials and proper drainage have helped. Think of a flattened hip roof. When framing a flat roof you will need to create a slight incline. Some roofs actually slope in several directions ensuring optimal water runoff.

Flat roof framing is relatively straightforward. The span rise run and line length. In the past most were constructed by packing the insulation directly above the internal ceiling finish in between the joists with a ventilation gap above. Shed gable hip gambrel and mansard.

From there the flat roof system you choose will determine the materials you apply. This will help you create a flat roof framing plan. Roofs are framed in five basic designs. Building a flat roof right.

In order to build any but a shed type roof including trusses you ll need to first determine a few factors. 2x framing wood joists timber framing laminated beams steel concrete or sips. The gable is the most common and it can be complicated with multiple roof lines including valleys and dormers. If you build a flat roof try to have it slope in multiple directions to drains or gutters.

Flat roofs are always built at a slight incline at least 1 8 inch per foot. Underneath the basics flat roofs are usually constructed with a ceiling nailed to joists which support a deck usually wood in residential construction a vapor barrier insulation and a roof board. Depending on the span many different materials can frame a flat roof.