Need help with building a two post arbor

[Joshua Welch]

I am wanting to build a two post arbor. This will be over an existing concrete slab. Will be posts, either 4x4 or 6x6. Then will sandwich something like 2x8s around the posts at the top. Then a few cross pieces 16" apart across the top, to make it look like a bigger pergola. A few questions I have, though.

1) Will some Simpson strong tie brackets hold this ok?
2) I was thinking of also putting in a floating bench. Would this help stabilize the whole thing?
3) How should I secure the bench? I thought some right angle Simpson brackets should be ok to secure it.
4) If I use cedar, I can stain/seal it immediately, right?

[Jim Terrill]

I am wanting to build a two post arbor. This will be over an existing concrete slab. Will be posts, either 4x4 or 6x6. Then will sandwich something like 2x8s around the posts at the top. Then a few cross pieces 16" apart across the top, to make it look like a bigger pergola. A few questions I have, though.

1) Will some Simpson strong tie brackets hold this ok?
2) I was thinking of also putting in a floating bench. Would this help stabilize the whole thing?
3) How should I secure the bench? I thought some right angle Simpson brackets should be ok to secure it.
4) If I use cedar, I can stain/seal it immediately, right?

If you are putting 2x8 on either side, you can just use carriage bolts. It's up to you, but I would use stainless, the galvanized can stain the cedar. Same fixation strategy goes for the bench, a single 3/8" bolt will support more than enough weight, go to 1/2" if you really want to go nuts. As for the finish, it depends on the moisture content. I have bought cedar decking at Lowes that was literally dripping wet, getting a finish to soak in was pretty tough and I had to refinish the chairs a year later. It also depends on what your finish is, I had good results with Australian Timber oil, even with the wet wood, but covering wet wood with spar varnish would be asking for trouble. The cross pieces could be done with metal braces, but I'm more of a fan of the TimberLok screws, they have more than enough strength and look a lot better. Just screw them in from the bottom of your cross pieces up into the "pergola" pieces. It will cost more than using a metal bracket but will look better.

[Ben Davis]

I agree with Jim.

The strongties are going to be just fine. The 4x4's will be more than enough, the 6x6's will probably look better. Wood magazine has a set of plans for a pergola that look great. They modified them to make a two post arbor between which they hung a gate. We're not allowed to post links, but you can easily find it on their website. Hope this helps!