Flat Roof Framing Design

Some roofs actually slope in several directions ensuring optimal water runoff.

Flat roof framing design.

Building a flat roof right. 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. In order to build any but a shed type roof including trusses you ll need to first determine a few factors. If you build a flat roof try to have it slope in multiple directions to drains or gutters.

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. Think of a flattened hip roof. 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. Flat roofs are always built at a slight incline at least 1 8 inch per foot.

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. A flat roof has a slope of 1 8 per foot to 2 12. 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.

The span rise run and line length. 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. This will help you create a flat roof framing plan.

You can do this with a foam layer that exactly fits your roof. Depending on the span many different materials can frame a flat roof. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. The gable is the most common and it can be complicated with multiple roof lines including valleys and dormers.

Shed gable hip gambrel and mansard. Flat roof framing is relatively straightforward. It is not ideal for snow or heavy rain but modern materials and proper drainage have helped.