The higher the snow load the closer the purlin spacing required.
How far apart do you put boards for porch roof.
The other issue is the building code.
If you go that length you must block it every four feet which you need to do anyway for nailing the plywood.
While your beam size ultimately depends on design factors such as whether you include a covered roof structure or open lattice strips a familiarity with conventional beam spans gives you an idea of how far apart you can space your posts.
In this example the section of roof is 20 feet wide and 14 feet from the fascia to the peak.
That s a long span.
If so you may want to go to 2 x 8.
Do you get a massive amount of snow.
Too high a snow load means the purlins fail regardless of how close together you put them because a 2 4 or 2 6 flat can only span a certain distance between trusses as snow loads increase.
The best size board to use is 1x4 pieces that are 10 feet long.
When you cut the rafters you ll need to make 3 separate cuts.
Before you cut your boards you ll need to measure the width of your building and calculate the exact length of each rafter.
This translates to seven rows of strips 20 feet long spaced two feet apart or 140 lineal feet of.
If not the patio roof only bears it s own weight and the block stiffens the joists dramatically.
The ridge cut also called the plumb cut at the top of the rafter the birdsmouth cut which itself comprises 2 different cuts where the rafter meets the building s wall and the tail cut at the base.
You do not have to brace all the trusses just plumb the second gable.
The common 4 on center design is suitable for snow loads up to 60 for most applications.
However you will want to have boards that can be used as braces for the tresses.