pergola support

[Bope]

We are having a paver patio put in and I was planning on building a pergola over it. The pergola is going to be free standing, not attached to the house. My thought was to put in some sonotubes and use a bracket on top to connect the post. At the top I would have some cross braces for support. The contractor putting in the patio didn't think that would be good enough. He thought there would still be too much movement in the posts. His suggestion is to sink the post in the concrete. I think his biggest concern is that 2 of the posts will have mock pillars about 3'-4' up around them. The way the pavers are designed there is a hole just big enough for a 4x4 to go up through the middle. I could attach the one side to the house but I have no experience dealing with the vinyl siding and figured it would just be easier to put in the extra posts. The posts next to the house would not have pillars around them. If I use a bracket on top of the concrete I would put the concrete level with the pavers and use molding around the bottom to hide the concrete. The contractor suggests putting the posts in the concrete and leaving that low enough to put gravel and pavers up to the post. My concern is the longevity of the posts and pergola. If the posts are bolted to footings they can be replaced. If the posts are sunk in the concrete replacing them would be impossible with out re doing the patio. The posts will be 4x4 PT wrapped in 1x cedar for looks. Any thoughts?

[jasfrank]

Find square tubing or weld some up then set those in the concrete. Drop your posts into them and run some screws and you should be as good as if the posts were in the concrete, but easy to replace at some point

[Mr_Mike]

The contractor is right. By setting the post below grade, you create a cantilever which will resist side loading way better than a post sitting on top of a pillar. Basically this is why a pole barn is so stout.

You could put diagonal supports between the uprights and the upper horizontal members. That would imply you have robust horizontal members both north/south and east/west. Many pergolas only have such members in one direction.

I do like jasfrank's suggestion of sleeved concrete, but it is also an expensive solution and you have to find suitably sized steel. The steel should be about 1/2" bigger than the post and you fill the gap with fine sand to make the post plumb.

[nowright]

Pergolas don't have any shear built in and acquire it by sinking the posts.  Need to sink at least 1/4 the height.  Put gravel in the hole, set post, pour concrete.  Gravel drains water from the post bottom and it'll last far longer.

[EdL]

Sink the posts.....and make darn sure you buy ones rated for ground contact.

Ed

[Lynden]

My thought was to put in some sonotubes and use a bracket on top to connect the post. The contractor suggests putting the posts in the concrete. My concern is the longevity of the posts and pergola. If the posts are bolted to footings they can be replaced. If the posts are sunk in the concrete replacing them would be impossible with out re-doing the patio. The posts will be 4x4 PT wrapped in 1x cedar for looks. Any thoughts?

There is an alternative to sinking the posts in the footings. Simpson makes the MPB44Z post base which is embedded in the top of the footing. The base is attached to the 4x4 post with screws. The MPBZ bases are pricy, but probably cheaper than custom-made sleeves.

https://www.strongtie.com/standoffpostba...ase/p/mpbz

http://www.dhcsupplies.com/resize/Shared...jpg?bh=400

[johndi]

I would be leery of sinking the posts in concrete, even those rated for ground contact.
Just removed a small fence I built because 4 of the posts that I sunk in concrete failed after 5 years.
Definitely need to sink post for sheer strength but need to provide drainage.

[Jasen]

I'm big on using post bases, Simpson Moment post bases are nice.
I hate posts set right into concrete, so do my guys seeing they just dug out the concrete of a rotted deck post in a tight spot on slop. A new post, 4 bags of Sakrete and a Moment post base and all is right in the world again, or at least the clients deck.

[Bope]

There is an alternative to sinking the posts in the footings. Simpson makes the MPB44Z post base which is embedded in the top of the footing. The base is attached to the 4x4 post with screws. The MPBZ bases are pricy, but probably cheaper than custom-made sleeves.

https://www.strongtie.com/standoffpostba...ase/p/mpbz

http://www.dhcsupplies.com/resize/Shared...jpg?bh=400

These look interesting. I originally was thinking of the post connectors that bolt to the top of the concrete footer with a J bolt. Where would I purchase these? My google search sis not turn up a place to buy them. Any tips on setting these? It looks like they want 4" of concrete around the MPB44Z post base, that means a 12" sonotube. Witht he posts covered with the stone pillars that should be easily hidden. The posts by the house I was hoping to only use a 6" tube therefore being able to hide the top of the the concrete with trim.

[MstrCarpenter]

The "big orange store" has 9' long 4x4 post sleeves for about $23. They have a little play to help plumb your posts, and you could still provide necessary drainage. I would still make sure the posts are rated for structural ground contact. (it used to be that common P.T. was .40 and structural ground contact was .60. In my opinion, the older treatment was a lot better.)
I think with a little research and a few calls, you might find that steel tube with leveling plates welded on the bottom and connection plates welded on top would yield superior results for the same or less $ as the Simpson hdwr. and they would last forever if protected from water. Your 10"-12" dia, footing could stop at the bottom of your pavers with 4 anchor bolts sticking up. The posts would be leveled and plumbed with nuts on top and bottom of the leveling plate, then the remaining space filled with structural flow-able grout. I've only brought this up because, even with a "lifetime warrantee" against rot or decay, I would not want to replace the posts in ten or fifteen years when the grape vines or roses have evolved into a permanent (prominent) part of your landscape.