How To Support 20 Foot Roof

The steeper the roof the more expensive the trusses get because the longer the boards get and the more roof area increases.

How to support 20 foot roof.

For example 4 12 pitch means 4 inches of rise in 12 inches of run. For a 20 foot span wood beam needs to be minimum 18 inches deep. On some roof trusses the 2 top chords extend down over the edges of the bottom chord creating a built in overhang. Almost any wood will do the same geometry of beam or truss is the important thing.

Multiplied by 40 pounds per square foot equals 8 000 pounds. If you think you d prefer an overhang style truss adjust the measurements for your top chords accordingly. Minimum roof loading is 20 lb sq. For a flat roof with snow loading this is 25 lbs.

There are several variables to consider when determining the proper rafter size. Better design with truss 2 feet deep or more depending on snow load. Large 8 x 8 posts are necessary for the use of supporting a porch roof. 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. For larger porches such as wrap around porches you will want to make sure that the support is more than you need. This number represents the total load that your roof must carry. Your top chords can protrude beyond the bottom chord anywhere from 1 3 feet 0 30 0 91 m.

I have a span of 26 feet. Multiply the load per square foot by the total area of the roof. The vertical rise of the top chord per 12 horizontal inches is the roof pitch or slope. If an example roof is 10 feet by 20 feet the total area is 200 square feet.

Per square foot for northern areas of the u s. For rooms which are heavily frequented it may be 50 lbs. Feet more in presence of snow. If smaller beam will sag ugly.

The larger the roof is the more support that you are going to need. 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. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.