Pergola Design and Rafter Sag

[Brad Ridgway]

I have posts in the grounds and will have beams up shortly...

posts are 6x6s which are layed out in two rows of three. they are 13' apart (26' width) and the rows are spaced 9' apart (deep). The beams will be (6) 2x10s sandwiched (and notched slightly) running the 9' depth with a slight overhang.

My struggle is the rafters which need to span 13' + the decorative overhang. I was hoping to use 2x8x16' and butt/anchor them together over the middle beam to get non-staggered look. Based on several calculators using minimal load i think that should be ok, but still worry about sag.

Thoughts?
-brad

[David Helm]

Since there won't be any load other than the weight of the rafters, they should be OK.

[Mike Wilkins]

I built a 12 X 14 foot patio cover a couple of years ago. I used a doubled 2 X 8 beam to span the 14' length, which was glued and screwed together. In the 2 years since construction, there has been no sign of sag or dip in this beam with the rafters spaced 16" OC. You should be OK, but if in doubt, you can always check span charts or hire an engineer.

[Dan Beckman]

I know this is an old thread but I will post anyway. I have the same question about beam design to span 14' between posts. The beams will support 2X8 rafters, 16" on centers. For the beams can I use 2X10's bolted to either side of the posts? Would 2X10's sandwiched together be stronger? I' m conned about avoiding long term sag of the beams.