Gable Roof Ridge Beam Size

Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

Gable roof ridge beam size.

This tells you the size of the beam needed to support the porch s roof. Also see assumptions for table development. Here we have a wood framed gable roof. This means the example porch would need a 6 inch by 8 inch beam.

There are several variables to consider when determining the proper rafter size. Loading conditions are detailed below. 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. The ridge board s length will be the outside measurement of the building plus the length of the overhang at both ends.

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. 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. Calculate the initial value for d then round it up to the nearest inch. For 2 x 6 rafters use a 2 x 8 ridge board and so on.

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. A ridge beam runs the length of the shed roof connecting every pair of rafters. Refer to sfpa s publication southern pine headers beams download in publications that includes all size selection and allowable load tables.

Continuing on from part 3. Ridge beams are required by code if the roof slope is less than 3 in 12 irc section r802 3. Choose a ridge board that is one size larger than your common rafters. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.

However our instructions include making shed rafters with a ridge beam. For each application a pdf download is available. This sizing guide for roof rafters will help determine what you need for your small project. Let s consider a basic gable wood roof framing design.