Pergola Beam & Rafter Sizes & Spans

because the only load they carry is the dead load of their own weight or a slight dab of snow, the 2x8s will probably handle it, but proportioqantely they might look small. Since a pergola is decorative as much as it is functional, I would use 2x10s

Excellence is its own reward!

Off hand I'd agree with the 2x10 but 14'... plus it's cedar, that's got to be close, plus you need to apply the math on the elasticity when wet due to the exterior nature of the project. If you added a post no problem... 7' w/2-2x10 ... 14'... I don't know... even if the rafters are only 6' I wouldn't want to call it engineered to code.

But also I'd add that here in this county in CA they treat a pergola just like a roof so we still have to apply a 40# /sq ft live load I believe it's due to the fact someone is going to get up there, be it a painter, or the next owner stringing xmas lights or even someone might apply roofing, you now that corragated crappolla... so I'd check with you local buidling dept if you have any doubts.

http://www.altereagle.com/

http://decks-ca.com

http://kingofcrown.com

Alter Eagle Construction & Design

IS 8'-9" TOO FAR OF A PERGOLA BEAM SPAN WITH DOUBLED UP 2x10'S...THIS MEASUREMENT IS BASED OFF OFF 14' SPAN WITH 3' KNEE BEACES ON EACH SIDE..I DONT WANT ANY BEAM SAG...

Quick note - I built a pergola with notched components about 8 years ago.

It looks cool & worked well for when I needed to take the rafters down (before a hurricane).

However - water will collect in the notches. In my case, even with pressure treated lumber, it rotted in many spots where the notches are.

I'm rebuilding it with fasteners... and without notches :)

What size of beam do I need for a 12 x 18 foot pergola?

I am planning to build a pergola with 4 x 4 posts at 9.5 foot and 11 foot spans for the short and long sides respectively. There will be three beams. they will hold approximately 400 lbs of total weight of additional wood and I wish to be prepared for approximately 1536 lbs of snow at one time. (1.6 lbs per square foot at 1 inch, for 120 square feet) so Thus, the total weight the three beams might have to hold would be 1900 total lbs. which equals approximately 16lbs per square foot. (The reason for the weight of snow is I plan on putting a tarp over the top in winter. So the snow will accumulate. I suspect the safety net would be the tarp would tear before the wood beam would fail.) Thanks