footings Raising how to fix?


Old 08-10-07, 08:53 AM
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footings Raising how to fix?

My footings on my 12' by 15' deck are raising the deck sits on 9 posts cemented into the ground the 3 by the house are fine the other six have defiently raised. The deck is now slanting toward the house. I was hoping to put the deck on floaters or and easy fix. Any help would be graetly appreciated.

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Old 08-10-07, 10:25 AM
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footings Raising how to fix?

Are you in a freezing climate?

If so, your deck post footing may not be deep enough, so the frost could heave them up. Trying to float them would be no good if the ground freezes again.

It sounds like the footings next to the house were protected or had better soil under them, but the others may have gotten frost under them.

The other possibility is that you could have expansive soil that lifted the concrete.

Old 08-10-07, 07:01 PM
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Welcome to and the Deck forum.

Dick told you both of the possible reasons why this has happened. What he didn't mention was the cure. Either way, you need to repour the footings and get them deeper. If you are in a frost area, ask your local bldg. dept. what the frost level is and go 6" deeper.

What I would do is to go half way between the existing interior footings and dig new ones, leaving the existing in place temporarily to support the deck. It won't be any fun to dig the holes (they never are), and it will be more difficult with the deck already in place above you. The proper size for the footings is determined by how far your beam is spanning and how far apart your beams are from each other. In a frost area, if your footings need to be 18" square, or 24" square, and say 15" thick, that's what needs to be at the bottom of the hole. The bottom of the footing needs to be as much as 42" below grade. That means that you dig the hole to the proper depth (42" in my example), fill the bottom 15" or 18" with concrete, then add a sonotube at the center of the footing and fill that so that it brings you about 6" above grade. Fill the sonotube with concrete and backfill around the outside of it with dirt as you come up. Work one footing at a time, because all of the concrete has to be done in a monolithic pour so that it binds together.

Once the interior footings have cured for a few days, cut new posts and lower the beam to the proper level. You'll probably need a couple of 6 ton bottle jacks to accomplish that.

Once the beams are lowered, then dig and pour the 2 outside footings. Once those have cured, post up to the beams.
Old 08-10-07, 08:26 PM
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footings Raising how to fix?

As usual, Lefty knows the best way to do things and I just analyze for the most part.

Don't let the up to 42" inches sacre you since we have 4 or 5 feet here. Most areas have much less. The important thing is for the bottom to be below what the local authorities have determined to be adequate based on history.

If you are not in a freezing area, but are in an area with some expansive soil, a larger footing with a Sonotube form to support the new post will also prevent soil heaving. The larger footing prevents uplift and the smooth sides of the Sonotube prevent the expanding soil from pushing the concrete upward.

Hand dug dug or rough-sided holes make it very easy for frost or expansive soils to raise post supports. The waxed cardboard is too slippery and uses less concrete.
Old 08-11-07, 04:54 PM
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4 or 5 feet! Dick, I sure am proud to be in the South. Gee, how do y'all deal with that? We get by with 18" or 24" depending on the soil. Great answers from you and Mike.
Old 08-11-07, 07:11 PM
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footings Raising how to fix?

We just build basements for the cheapest square footage you can get.

For decks, we just go a little deeper for the one time we build decks. - Then we get to enjoy the deck for the 5 days of summer but can use it to grill all winter.

Not enough snow - it is bad when your frost depth is more than the total annual snow fall.


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