enter image description hereI have a 12' x 12' deck with posts set at 6' on the sides & 4' on the front. There are 2 x 6 along the outside at the top of the posts. I would like to add pergola beams across the top,side to side to cut the sun a bit. Will the 2 x 6's hold those beams or should I add another 2 x 6 to the inside for more support?

Thank you.

  • A photo would most helpful. Post set at 6' and 4'? what does that mean. 2x6 at the top? how? more details and a photo please.
    – Alaska Man
    Apr 7, 2019 at 17:54
  • Also tell us what "pergola beams" mean in this case, including quantity.
    – isherwood
    Apr 7, 2019 at 22:00
  • Sorry, I don't know what the beams are called across the top of a deck that help block some sun, but I'm not putting trellis slats across after the 2 x 8's or 2 x 6's I space across the top. I'm debating on putting them every foot, so 12 boards in total.
    – Kim Dobson
    Apr 8, 2019 at 22:51

1 Answer 1


A 2x6 weighs about 2 lbs. per foot, so each 2x6 will weigh about 2 lbs. x 12’ span = 24 lbs.

Half the weight will be carried by one end, so the weight on each end will be about 12 - 16 lbs. per foot (if the 2x6’s are 12” o.c.) and there are miscellaneous 2x2 wood strips on top too.

A 2x6 roof joist support can carry about 150 lbs. per foot, depending on the species and grade.

So, structurally you do not need to add another 2x6 to support your pergola Beams (2x6’s), but you may want to for appearance.

See these designs

Remember, the best wood for exterior use and natural finish will be cedar or redwood...but you can always paint pressure treated wood.

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