Deck raised again due to frost heave!

[user1234]

2 summers ago we put in a new deck. Unwise at the time, we didn't know that we required a permit to replace a deck so no permit was used. We did use a sonotube but we put the post in the tube along with the concrete at the advice of a local lumber yard. We found out after that we should have placed the metal connector on the top of the concrete at the top. I don't know if this has anything to do with the problem we are now having as the issue that I became aware of was that it could cause the wood to prematurely rot. We did put the concrete down to 5' instead of the recommended 4' (Ottawa) since we thought this would protect even more against frost heave.

Last year, our deck raised around 3" and we accepted that it could just settle that way. This year around 3" more! We have a definite slope towards the house now. I'm not sure what to do to fix this. Should we rip out these posts and replace them? We have a high water table, so could that be the problem - should we not have gone to 5'? Should we undo the bolt at the top and cut the post shorter? Is there anything that we can do that would prevent this from happening again???

All assistance is greatly appreciated!

 

[nealtw]

You will probably have to do this again,the five feet should have been enough, next time try to make the bottom of the hole a little bigger around and hold the tube up a little so you create a footing at the bottom, slide in a couple peices of rebar and use a saddle. Don't know why you are having problems but you could shorten the post as temp fix.

 

[joecaption]

Just because you put the post in concrete does not mean it's going to rot as long as you were using pressure treated lumber that's below ground rated.
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[user1234]

You will probably have to do this again,the five feet should have been enough, next time try to make the bottom of the hole a little bigger around and hold the tube up a little so you create a footing at the bottom, slide in a couple peices of rebar and use a saddle. Don't know why you are having problems but you could shorten the post as temp fix.

We did bell the bottom and lifted up the sonotube to help create the footing. I would have thought it would be enough. I hadn't thought about the rebar and will include that if we do end up pulling it all out - as well as the saddle.

 

[nealtw]

Are you sure your house isn't sinking? It should have worked.

 

[siriuschaos]

It is possible that if you built the deck at the same time as the house (say in 1 of those cookie cutter subdivisions where new houses pop up daily) that the
soil surrounding the home hasn't settled sufficiently. If this is the case, its a good bet to play the waiting game for a year before attempting attached projects outside. Even though your new home has sod or a lawn doesn't necessarily mean the sub soil was compacted properly. Back filling is usually done with a back hoe but rarely is it compacted sufficiently (due to possible collapse of the foundation from incorrect or excessive compacting) Its always best to let Ma Nature do the compacting. On the other hand if the home is a half a dozen years old or more, an upheaval of the magnitude you describe would indicate forces at work somewhere. Is there road construction nearby?
Have you spoken to your neighbors to see if they experienced similar problems?
Was the concrete aerated around the post initially? Was the diameter of the sonotube sufficient enough to carry the point load of the timber used? IE. 6x6 post= minimum 12" diameter. There are a number of variables involved if your structure is moving that much.

 

[nealtw]

Did the concrete come up or did the post come up thru the concrete and how deep is the post, all the way to the bottom?