How To Support 20 Foot Roof

If you think you d prefer an overhang style truss adjust the measurements for your top chords accordingly.

How to support 20 foot roof.

Per square foot for northern areas of the u s. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. This sizing guide for roof rafters will help determine what you need for your small project. For rooms which are heavily frequented it may be 50 lbs.

The vertical rise of the top chord per 12 horizontal inches is the roof pitch or slope. Multiply the load per square foot by the total area of the roof. Your top chords can protrude beyond the bottom chord anywhere from 1 3 feet 0 30 0 91 m. For a flat roof with snow loading this is 25 lbs.

Calculate the weight the beam must support. For a 20 foot span wood beam needs to be minimum 18 inches deep. For larger porches such as wrap around porches you will want to make sure that the support is more than you need. If smaller beam will sag ugly.

Large 8 x 8 posts are necessary for the use of supporting a porch roof. 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. On some roof trusses the 2 top chords extend down over the edges of the bottom chord creating a built in overhang. I have a span of 26 feet.

Better design with truss 2 feet deep or more depending on snow load. Multiplied by 40 pounds per square foot equals 8 000 pounds. For example 4 12 pitch means 4 inches of rise in 12 inches of run. The steeper the roof the more expensive the trusses get because the longer the boards get and the more roof area increases.

Multiply the loading per square foot by the area in square feet of the surface which the beams will be supporting. If an example roof is 10 feet by 20 feet the total area is 200 square feet. There are several variables to consider when determining the proper rafter size. Almost any wood will do the same geometry of beam or truss is the important thing.

Minimum roof loading is 20 lb sq. Feet more in presence of snow. The larger the roof is the more support that you are going to need.