I'm building a new deck and pergola in my backyard. The deck is pretty much done, and the pergola posts are in. I'm now I'm trying to decide how to finish up the pergola.

Deck is roughly 12 feet wide and 24 feet long. It's a rectangular shape with the corner cut off, so it makes building the pergola interesting. I've decided to go with 5 posts for the pergola (all 6x6), with a cross beam over the cut off corner. I'm then planning on having the pergola rafters/joists overhang symmetrically with the cut off corner of the deck.

Deck is built on 9 posts, poured concrete 4' deep. The pergola posts are secured onto Pylex foundation screws 4' deep and then also secured to deck and blocked it (you can swing on them and they won't move). Everything is cedar (PT under the deck, but boards and posts and all the other pergola materials will be cedar).

I'm trying to decide what to do for the pergola beams and rafters/joists. I've had some feedback saying just use 2x8 for the beams and 2x6 for the joists, and then add strips running perpendicular on top to prevent rotation, although after searching around online I've seen people mention that 2x8 and 2x6 may look too small with the 6x6 posts.

I've attached a diagram of what I'm looking to do, along with a picture of it at its current state. The alternative I was thinking about was 2x10 beams with 2x8's for the rafters.

The overhang that I'm proposing to create is also a bit of a concern since I don't want the ends of the joists to sag.

I'm looking for structural feedback along with aesthetic feedback (if 2x8 and 2x6 will work but look like trash then I'd rather just go up a size).

enter image description here

  • 1
    Pergolas I've built on that scale have beams of full-dimension rough-cut 2x12 (doubled). To span 14 feet I wouldn't go smaller than 2x10 actual or 2x12 nominal. That said, this is really a matter of prerogative (design taste) since code probably doesn't apply. As such, it's off topic here. Good luck. Looks great.
    – isherwood
    Aug 4 '20 at 20:15
  • take your photo and draw in the pergola beams. compare the height of the beams you drew with the size of pole to find the ideal size for the look you want.
    – Jasen
    Aug 5 '20 at 8:43

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