Pergola build project?

I am building a 10’x20’ pergola made of pressure treated wood. Planned on using 3-8”x8” posts secured into the concrete patio and the other end into the brick on the house. 2-2”x10” sandwiched on either sides of the posts as well as for the rafters and spaced every 16” and 2”x2” slats spaced 8” on center.  Does this sound ok?  Thanks. 

2 Answers

  • 1 month ago

    strength against wind loads [and other pressures like clumsy guest hitting the post] comes from building structures with triangles, not right angles.  your proposed structure doesn't have any.  You NEED them at both the feet of your uprights and where the uprights connect to the headers [your 2x10s].  The longer these are, the more stable your structure will be.  AND they need to run in multiple directions -- at minimum, east-west and north-south [but preferably three directions].  Guy wires under tension from the upper ends to the ground might serve -- and you'll NEED serious ground anchors [like 1.5 inch iron pipe five feet long driven into the ground with a sledge hammer six or more feet away].  Next point:  Masonry is strong under compression loads but weak under tension.  your anchors in the brick might serve for downward force, but won't be useful against a pulling away from the wall motion.  Securing your house end  of the structure under the eaves [if this side has first story eaves] to the ends of the trusses using carriage screws would be far better.  If that's not possible, consider making a vertical [wood] brace that goes up to where the upper end can be attached [carriage screws] to either the wood behind the gable end of the house, or the wood in the second story wall, or the roof truss [yes, it would be far above if two stories tall].  Anchor the lower end into the brick work so that pulling motion away from the gazebo attachment in the mid area pulls against the bolts at top and pushes against the brick facade [it's a lever if you look at it] [this may require a guy wire from near the top of this vertical to at least half way out the gazebo -- or all the way to the posts].  -- grampa

  • Edwena
    Lv 7
    1 month ago

    The brick facade on a house is decoration, not structural.  Likewise, your posts need to be rigid in the ground, not bolted to the top of the concrete patio.  Your pergola will rack from a lateral wind load.  

Still have questions? Get answers by asking now.