Wood Frame Flat Roof Detail

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.

Wood frame flat roof detail.

1 8 pitch is given so 24 x 1 8 equals 3 or unit of rise in inches. The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls. For additional stability you can also use steel joists that are built into one or both of the walls. Flat roofing under construction plywood decking is then used to cover the joists with the width in between also determined by the weight being placed upon them.

Conventional light frame wood structures may be built without the need for engineering analysis of each component. Figure 2 2 roof framing terms. Getting the balance right here is crucial as too much weight will inevitably lead to an unstable roofing structure. This will give additional stability to the roof structure.

Within limitations which include among others building size roof pitch and design loads the allowed span for conventional rafters can. The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure. Post and beam framing 42 roof slopes 44 flat roofs 45 pitched roofs 45 valleys 48 dormers 48 overhangs 48 ridge beam roof details 49 lightweight wood roof trusses 49 chapter 8 wall sheathing 53 types of sheathing 53 corner bracing 54 installation of sheathing 54 chapter 9 roof sheathing 58 lumber sheathing 58. From there the flat roof system you choose will determine the materials you apply.

If the unit of rise in inches is 3 then the cut is the unit of rise and the unit of run 12 inches or 3 12. The provisions for prescriptive roof construction are found in chapter 8 of the irc and in section 2308 of the ibc. Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. Of course you don t need to live in a modern house to deal with a flat 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. Line length is the hyptenuse of the triangle whose.