cement pad over deck pilings

Lincada · 06-08-2012, 01:47 PM

Hi there, I am building a raised deck (9' in the air), and having a cement pad poured under it for the patio. I will have to have a 12' x 12" hole dug for the piling. The piling will end up being under the patio, and someone told me to use a sonotube for the portion of the piling that will be in contact with the patio...so that the piling and patio will be effectively separate (cement for piling and patio is being poured at the same time). Does this sound appropriate, and will the top edge of the sonotube be showing on the surface of the patio (it will be flush with the surface of the patio). I'm having a stamped concrete finish.

Canarywood1 · 06-08-2012, 04:16 PM

Quote:

Originally Posted by Lincada

Hi there, I am building a raised deck (9' in the air), and having a cement pad poured under it for the patio. I will have to have a 12' x 12" hole dug for the piling. The piling will end up being under the patio, and someone told me to use a sonotube for the portion of the piling that will be in contact with the patio...so that the piling and patio will be effectively separate (cement for piling and patio is being poured at the same time). Does this sound appropriate, and will the top edge of the sonotube be showing on the surface of the patio (it will be flush with the surface of the patio). I'm having a stamped concrete finish.

Well,first off pilings are usually driven into the ground,are you maybe talking about a pier for a footing??

danpik · 06-08-2012, 06:28 PM

A lot of this will depend on the area you are in. If you are in an area where there is frost heave. the sonotube footers/posts will have to come up thru the finished concrete surface. The tops can be even with the finished surface but need to be separate so the slab can move up and down as the seasons change. If you put the slab over the tubes, the slab will try to lift and the tubes will not. The results will be cracking of the slab.

The best way to do this is to set the tubes to the height of the finished patio and fill them with concrete. After they have set for a couple days, pour the patio slab. If everything is done correctly the tops of the slab will be flush with the tops of the tubes. The sonotube cardboard will eventually rot away and leave a nice even joint aroungd the foorings.

Lincada · 06-18-2012, 12:41 PM

Alright, so I talked with the guys pouring the cement. They recommend that I pour the piling, and the patio over it, all at once (no sonotube). Then when it's set, drill a hole thru the patio into the piling and insert a saddle for the deck post to sit in. They recommended against the sonotube because it will look terrible, and also because I already have one deck post that is cemented into a piling (as in, I have a deck, but I am adding to it, so will be putting in another post for the new deck). Since I already have a post/piling that the patio will be going around/over, I can't really use a sonotube around that one...we do get frost, but the piling will go well below the frost line by about 8 feet. My concern is: does this sound like an ok thing to do...or is it going to crack the patio?

drtbk4ever · 06-18-2012, 01:49 PM

Quote:

Originally Posted by danpik

The tops can be even with the finished surface but need to be separate so the slab can move up and down as the seasons change. If you put the slab over the tubes, the slab will try to lift and the tubes will not. The results will be cracking of the slab.

I have to agree with danpik.

Canarywood1 · 06-18-2012, 07:34 PM

Quote:

Originally Posted by Lincada

Alright, so I talked with the guys pouring the cement. They recommend that I pour the piling, and the patio over it, all at once (no sonotube). Then when it's set, drill a hole thru the patio into the piling and insert a saddle for the deck post to sit in. They recommended against the sonotube because it will look terrible, and also because I already have one deck post that is cemented into a piling (as in, I have a deck, but I am adding to it, so will be putting in another post for the new deck). Since I already have a post/piling that the patio will be going around/over, I can't really use a sonotube around that one...we do get frost, but the piling will go well below the frost line by about 8 feet. My concern is: does this sound like an ok thing to do...or is it going to crack the patio?

If that pier will be 8 feet below the frost line i'd do it the way your guy's suggest,much neater installation.

danpik · 06-18-2012, 09:16 PM

Quote:

Originally Posted by Canarywood1

If that pier will be 8 feet below the frost line i'd do it the way your guy's suggest,much neater installation.

In Sarasota you might be able to get away with it. In areas where there is frost there is heaving. When the ground freezes it raises up. If the piers were 100' deep the patio slab will still heave up in the winter and the posts will not. Something will have to give and the failure point will be right around the connection area of the slab and the pier