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-   -   Pergola footings for new concrete patio slab (https://www.diychatroom.com/f19/pergola-footings-new-concrete-patio-slab-627506/)

braydon2k 05-17-2018 10:59 AM

Pergola footings for new concrete patio slab
 
Hello everyone

First post so let me know if I need to give any additional info

I will be pouring a new concrete patio soon to replace my old wood deck. It will be aprox. 4 inch thick fiber reinforced with wire mesh reinforcements as well. The whole slab will be about 750 sq. ft total.

I have an existing 12x12 (14x14 total roof overhang)gazebo with 4x4 posts(posts will probably be replaced with 6x6) and I would like it to sit on top of the new patio like it did on the old deck.

I have heard the preferred way to do this is to pour footings about 4ft deep(i live in Michigan) with sonotubes and attach Simpson strong tie brackets to them for mounting the posts.

My question is, can I dig out the holes for sonotubes and just do 1 big uniform pour where the footing tubes fill but then just become part of the patio slab? this way the footings are invisible and you would never know they were there. Or should footings be completely separated from patio concrete?

If they should be separate, do i just use like an expansion joint between where footers and patio touch? or can the thickness of the sonotubes act as a barrier to separate them?

Hopefully you have a good idea of what I'm trying to accomplish

Thanks in advance

Nealtw 05-17-2018 11:14 AM

Re: Pergola footings for new concrete patio slab
 
Your footing is deep for frost protection but the slab will be on the surface where it could be moved with frost. We try the get the top of the concrete pier level with the slab. you can fill the top of the tube sides to make it square and about the size of the post for the top 6".
Cut a 5" square hole in a piece of plywood and center that hole over the tube reach inside and trace the shape with a pencil. Now you have a pattern for the 2x6 to add to the plywood that fits in the tube.

braydon2k 05-17-2018 11:28 AM

Re: Pergola footings for new concrete patio slab
 
Thanks for the info Neal

im trying to picture what you mean. So I take the 8 inch sonotube and create a wood pattern to narrow the top 6 inches of the footing into a square at the top? does that sound right.

so would you pour footings separate and wait for them to set before I pour patio? do you pour patio and have it touch right up with footing or do you have anything acting as a barrier between footing and patio? like sonotube walls or expansion joint?

Thanks

Nealtw 05-17-2018 11:47 AM

Re: Pergola footings for new concrete patio slab
 
Quote:

Originally Posted by braydon2k (Post 5499234)
Thanks for the info Neal

im trying to picture what you mean. So I take the 8 inch sonotube and create a wood pattern to narrow the top 6 inches of the footing into a square at the top? does that sound right.

so would you pour footings separate and wait for them to set before I pour patio? do you pour patio and have it touch right up with footing or do you have anything acting as a barrier between footing and patio? like sonotube walls or expansion joint?

Thanks

Word salad.
Footing the bottom of a bearing point or wall usually about 8" thick, square and bigger than a pier or wall to spread the load over a bigger area.
Concrete pier formed with a lumber or tube on top of a footing usually with rebar inside the concrete may or may not be connected to the rebar in the footing.

Depending the weight of the structure and the soil condition sometimes the footing is not needed the size of the tube would be good enough.
Back to your question. we just let the concrete slab run into the pier but I have see others worry about it and put spacers between. Then you see a frame out of 1x4 loosely fit around the pier and wedged in place for easier removal. Or just wrap the pier with 1/2" foam board and leave that there.

jlhaslip 05-17-2018 03:00 PM

Re: Pergola footings for new concrete patio slab
 
Another approach is to place the footings and sonotube to the underside of the slab, pour them as a seperate pour and then pour the slab over top. Mount the Simpson brackets.
After the pour, use a diamond blade to cut a square pattern to release the slab and caulk the cut so water doesn't get in. This allows the slab to move in frost but the posts remain stable.


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