Flat Roof Framing Design

Roofs are framed in five basic designs.

Flat roof framing design. When framing a flat roof you will need to create a slight incline. It is not ideal for snow or heavy rain but modern materials and proper drainage have helped. Building a flat roof right. Flat roof framing is relatively straightforward.

If you build a flat roof try to have it slope in multiple directions to drains or gutters. Depending on the span many different materials can frame a flat roof. Think of a flattened hip roof. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof.

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. You can do this with a foam layer that exactly fits your roof. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. The span rise run and line length.

Some roofs actually slope in several directions ensuring optimal water runoff. A flat roof has a slope of 1 8 per foot to 2 12. In order to build any but a shed type roof including trusses you ll need to first determine a few factors. Shed gable hip gambrel and mansard.

From there the flat roof system you choose will determine the materials you apply. It can be framed like a floor system with horizontal framing members at 16 19 or 24 o c. On a basic level flat roof construction comes in the form of roofing timbers or joists as they are more commonly known or steels that are laid across two uprights walls in most cases. There are two types of flat roof system and they differ according to whether the insulation is above or below the structural roof deck.

This will help you create a flat roof framing plan. 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. The gable is the most common and it can be complicated with multiple roof lines including valleys and dormers.