How To Support 20 Foot Roof

Calculate the weight the beam must support.

How to support 20 foot roof.

Multiplied by 40 pounds per square foot equals 8 000 pounds. This number represents the total load that your roof must carry. For a 20 foot span wood beam needs to be minimum 18 inches deep. If smaller beam will sag ugly.

Just keep in mind that if the length of the board size is more than 20 feet then you need to use a more expensive type of lvl board and not a traditional pine board for this longer length. For a flat roof with snow loading this is 25 lbs. If an example roof is 10 feet by 20 feet the total area is 200 square feet. The vertical rise of the top chord per 12 horizontal inches is the roof pitch or slope.

For rooms which are heavily frequented it may be 50 lbs. I want to know if i take 2x4 s and routed 2 1 2 in channels the length of the 2x4 and used 1 2 inch x 5 inch plywood sandwiched between will support the 26 foot span of roof read more. Per square foot for northern areas of the u s. If you think you d prefer an overhang style truss adjust the measurements for your top chords accordingly.

Multiply the loading per square foot by the area in square feet of the surface which the beams will be supporting. This sizing guide for roof rafters will help determine what you need for your small project. Finally the truss calculator will compute the best dimensional method to connect the pieces of the truss with steel joints and a bridge. Feet more in presence of snow.

Almost any wood will do the same geometry of beam or truss is the important thing. Multiply the load per square foot by the total area of the roof. Better design with truss 2 feet deep or more depending on snow load. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.

For larger porches such as wrap around porches you will want to make sure that the support is more than you need. There are several variables to consider when determining the proper rafter size. Minimum roof loading is 20 lb sq. The larger the roof is the more support that you are going to need.

For example 4 12 pitch means 4 inches of rise in 12 inches of run. Your top chords can protrude beyond the bottom chord anywhere from 1 3 feet 0 30 0 91 m. The steeper the roof the more expensive the trusses get because the longer the boards get and the more roof area increases.