How To Size Roof Ridge Beam

Timber steel framing manual single span ridge beam.

How to size roof ridge beam.

It has been my experience to never use a beam smaller than a two ply 2 x 8. Multiplied by 40 pounds per square foot equals 8 000 pounds. These small areas are usually door opening on the interior and people are trained that these areas are the strongest place in a house to be in the case of an emergency. For 2 x 4 rafters use a 2 x 6 ridge board.

A ridge board is a non structural member that serves as a prop for opposing rafters to rest against and connect to. Multiply the load per square foot by the total area of the roof. Versa lam lvl size chart laminated beam span tables charts. Also see assumptions for table development.

Ridge beam sizing is based on the span of the beam between supports and the amount of roof load supported by the beam. Ridge beams are required by code if the roof slope is less than 3 in 12 irc section r802 3. Ridge beam height above top of slab height of wall z. Loading conditions are detailed below.

For each application a pdf download is available. If an example roof is 10 feet by 20 feet the total area is 200 square feet. The ridge board s length will be the outside measurement of the building plus the length of the overhang at both ends. This number represents the total load that your roof must carry.

Refer to sfpa s publication southern pine headers beams download in publications that includes all size selection and allowable load tables. For 2 x 6 rafters use a 2 x 8 ridge board and so on. The formula for determining the finished height of the ridge beam from the top of the slab to the top of the ridge beam is. Step 1 choose a ridge board that is one size larger than your common rafters.