Gable Roof Ridge Beam Size

The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial.

Gable roof ridge beam size.

The ridge board s length will be the outside measurement of the building plus the length of the overhang at both ends. Choose a ridge board that is one size larger than your common rafters. This means the example porch would need a 6 inch by 8 inch beam. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.

Floor beam span tables of residential structural design we will now look at roof rafter and beam design. After they re up you can snap a line to mark and trim the tails in a nice straight line to make up for any ridge warp or marking cutting and fixing errors. Loading conditions are detailed below. Ridge beams are required by code if the roof slope is less than 3 in 12 irc section r802 3.

Let s consider a basic gable wood roof framing design. The typical gable roof diagram above shows the r length measured from the outside wall to the middle of the ridge beam the rafter section diagram below typical of a shed or patio cover roof shows the r length measured from the outside wall to the outside face of the ridge beam either one is acceptable depending on which type of roof you are building but if you are using the. A ridge beam is a structural member used to support the ends of the rafters at the ridge transferring it s loads to posts or gable end walls. Here we have a wood framed gable roof.

Refer to sfpa s publication southern pine headers beams download in publications that includes all size selection and allowable load tables. Calculate the initial value for d then round it up to the nearest inch. Some shed rafters do not incorporate ridge beams either due to small size or lack of technical know how. For 2 x 4 rafters use a 2 x 6 ridge board.

Gable roof framing calculator plan diagram with full dimensions for a good straight fascia add an extra inch or 2 to the tails of all your rafters total length. Continuing on from part 3. However our instructions include making shed rafters with a ridge beam. This sizing guide for roof rafters will help determine what you need for your small project.

Also see assumptions for table development. For each application a pdf download is available. There are several variables to consider when determining the proper rafter size. For 2 x 6 rafters use a 2 x 8 ridge board and so on.