How far can you span a pergola?
Considering this, how far can a 2x12 span for a pergola?
There's not quite enough information here to give a definitive answer, but for decks, a rule of thumb is when supporting joists that span 12 feet, a double ply beam can span in feet a value equal to its depth in inches. Thus, a double 2x12 beam could span 12 feet - with 20' beams, posts at 10' might look the best.
Also Know, how far apart should pergola posts be? Spacing the rafters 16 to 20 inches apart is common. The most important rule in spacing is to keep the distance consistent between all the rafters. Install the front and rear rafters first, fastening them to the face of the support posts above the girder.
Regarding this, how far can a 2x10 span for a pergola?
A 4x4 does make a good knee brace when 6x6 posts are used. Also a 2x10 can span 13'9" when being used as a deck joist so I am not sure why it couldn't easily carry 14 feet on a pergola which is going to halve 75 percent less load on it.
What size lumber can span 20 feet?
Re: 20 foot clearspan beam size In that case, you need something like a 12-16" GLULAM or LVL to span the 20' and can use simple 2x8-10 dimensional lumber 16"OC as floor joists.