I’m looking to build a pergola, (outside shade arbor) 4 posts, 12×12 foot spread. It will be free standing – not attached to any other structure. Couple of questions:
1. Post anchoring. I’ve had suggestions to sink the posts (either 4×4 or 6×6 wolmanized) in concrete, or to use post brackets into a concrete footing. Pros and cons for either?
2. I’m planning on using 2 x’s on both sides of the posts as headers. How should I size them. Would I need 2×12’s for the 12 foot spread or could I use less since no real roof loading?
3. I’ll be enclosing the posts with hollow round columns that I already have, that came with the foam base and top cap. What would be the best way on keeping the column centered and stable to the posts? The round columns would not be load bearing,
Thanks
Replies
With that load you could get away with 2x6's. To center the covers attach some 2x4 blocks on the posts that will touch the inside of the column cover on all four sides top and bottom then slip the covers over them. Be sure you leave a way for the water that will try to fill up the column cover to drain out of the bottom.
I'm curious about your foam base and cap - haven't seen that before. Are you sure they will hold up to the elements?
Kevin Halliburton
"I believe that architecture is a pragmatic art. To become art it must be built on a foundation of necessity." - I.M. Pei -
Thanks, glad to hear that proportion is my main concern. Don't know about the strength of the foam. Appears rigid enough, and probably more insect proof than wood.........Ed
Mister Ed, The load is maybe not what you want to be concerned with, it's the how's it gonna look that dictates the size of your beams.
You might want to cruise the web and see what turns up to get some idea of the kind of the proportions that work. Drive around town and you can find the examples of what doesn't, they stand out.
Joe H
I'm planning the same type of project for my patio. One side will be anchored to the house. I was thinking of sinking galvanized pipe into holes, filling the holes with 'crete and slipping the columns over the pipe. I was going to cut some 2X wheels to epoxy to the pipe, top and bottom, for fastener purchase through the columns. My thought was to cut the top wheels a little loose so I could adjust the column plumb and tap some shims in between the inside of the column and the wheels, then good poly adhesive and fasteners.
I'm stumped with how I want the joists (is that what you call the horizontal members of a pergola?) to connect to the house.
Ditch
Reduced.Ditch
Ditch,
That looks like a beautiful place for a pergola. Good luck with that. I'm sure it will look great!
Mr. Ed,
Have just finished making a few of these....
2x8 headers on both sides of the posts
2x6 cross slats.
The larger dimensional lumber gives you the opportunity to make some really nice scroll work on the ends and looks better in the overall scale. Don't worry about any "load".
Be careful not to use any dimensional lumber that is too small. For instance, some folks like to include 2x2 cross slats on top of the first set of cross slats. Then they get those crazy vines to grow up the pergola and since the vine is so strong it takes the small lumber anywhere it wants to go. Even without vines and such, smaller lumber will have a tendency to whoop all over the place at the unsupported ends and look untidy. Of course the way around this is to not let any smaller lumber hang out very far from any support.
Good luck
Rob Kress
Thanks for all the reply's.
I'd like to rephrase the post question. I'd prefer to use the metal brackets to the concrete, rather than sinking the posts. Longer posts, tougher to find straight lumber. If the top of the posts are well connected, similar to a table top, shouldn't the brackets be stable and strong enough? I'd think the ability to fine tune squareness, and plumb with the brackets would trump the additional strength of sinking the posts. What do you think?
If you go this route I would recommend a kicker brace from the post to your headers in all four directions. A top heavy free standing structure will need the additional bracing if you don't sink the posts.Kevin Halliburton
"I believe that architecture is a pragmatic art. To become art it must be built on a foundation of necessity." - I.M. Pei -