How To Size Roof Ridge Beam

If an example roof is 10 feet by 20 feet the total area is 200 square feet.

How to size roof ridge beam.

Loading conditions are detailed below. Step 1 choose a ridge board that is one size larger than your common rafters. It has been my experience to never use a beam smaller than a two ply 2 x 8. 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. This number represents the total load that your roof must carry. Timber steel framing manual single span ridge beam. The ridge board s length will be the outside measurement of the building plus the length of the overhang at both ends.

Refer to sfpa s publication southern pine headers beams download in publications that includes all size selection and allowable load tables. Once the ridge beam has been positioned in place and supported by roof framing members you can determine the placement of a rafter by measuring down from the top of the beam y height and making a mark on the beam. For each application a pdf download is available. Also see assumptions for table development.

Multiplied by 40 pounds per square foot equals 8 000 pounds. Versa lam lvl size chart laminated beam span tables charts. No matter what the specs say. For 2 x 6 rafters use a 2 x 8 ridge board and so on.

For 2 x 4 rafters use a 2 x 6 ridge board. Multiply the load per square foot by the total area of the roof. Ridge beam sizing is based on the span of the beam between supports and the amount of roof load supported by the beam. 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.