Flat Roof Framing Design

Think of a flattened hip roof.

Flat roof framing design.

Some roofs actually slope in several directions ensuring optimal water runoff. When framing a flat roof you will need to create a slight incline. There are two types of flat roof system and they differ according to whether the insulation is above or below the structural roof deck. A flat roof has a slope of 1 8 per foot to 2 12.

Flat roof framing is relatively straightforward. 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. 2x framing wood joists timber framing laminated beams steel concrete or sips. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure.

You can do this with a foam layer that exactly fits your roof. Flat roofs are always built at a slight incline at least 1 8 inch per foot. It can be framed like a floor system with horizontal framing members at 16 19 or 24 o c. 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.

The gable is the most common and it can be complicated with multiple roof lines including valleys and dormers. This will help you create a flat roof framing plan. It is not ideal for snow or heavy rain but modern materials and proper drainage have helped. Shed gable hip gambrel and mansard.

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. In order to build any but a shed type roof including trusses you ll need to first determine a few factors. Roofs are framed in five basic designs. 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.

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. Depending on the span many different materials can frame a flat roof.