pergola design help
I'm having a 14' x 11' pergola built in the back yard. The posts and beams are 6x6. The rafters are 2x6. I think it's a pretty simple design but I am concerned about the 14' span on the 6x6 beams. I fear that without a post in the middle of that 14' span there will be dipping and warping. Can you recommend a method to engineer the beams so they don't dip without putting a post in between? Maybe some connectors? Also please note that the beams are attached to the posts (not resting on top of them).
Please see the link below for design specs: