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  1. #1
    Join Date
    May 2009
    Location
    Wisconsin
    Posts
    4

    Exclamation Massive heaving on deck and patio in clay soil

    I had a deck built in 2006. The deck is over a walkout basement. Every winter the deck heaves in certain areas about 6" causing the upper patio door to pinch shut. The deck posts are on 12" diameter sono tubes and 4 1/2' deep (which according to the city I live in is below frost depth). Also, I had a patio and outdoor kitchen installed that also heaved 3+" causing damage to my siding on the house, pinched the basement patio door shut and now that spring is here, has not leveled out with the spring thaw. I have had 2 patios installed (1 concrete which was removed last year in favor of a paver patio). The new patio was set on about 18" of washed stone with a drain tile system to daylight with crushed limestone and the pavers on top. The kitchen area has pulled away from its retaining wall it was built against and the granite countertop has cracked in half. The kitchen was built on the original concrate patio so it only has about 4" of crushed road gravel underneath the slab. I am in desperate need of some advice on how to resolve this. There had been some water issues the past few years with city water junction boxes leaking. Could I have water from the city under my house causing this? What can I do? Any responses would be very appreciated. If you have any further questions, please ask!

  2. #2
    Join Date
    Apr 2008
    Posts
    74

    Default Re: Massive heaving on deck and patio in clay soil

    I'm no expert, but is it possible the house itself is heaving/uplifting and/or sinking and not the deck and/or patio?

    Perhaps it is a footing problem with the house and not the add-ons and it just wasn't noticed before they were added on (i.e. they are stationaly and the house is "falling" onto them, giving the appearance of heaving)?

    Just another option to look into.

    Good luck, Tim

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Massive heaving on deck and patio in clay soil

    Every winter the deck heaves in certain areas about 6" causing the upper patio door to pinch shut
    .
    Is this door on the exterior wall of the house or is this door part of a structure on the deck ?
    Typically a raised deck would be attached to a ledger connected to the house framing. If the deck is heaving this area shouldn't be moving.

    The deck posts are on 12" diameter sono tubes and 4 1/2' deep (which according to the city I live in is below frost depth).
    Two things come to mind ....

    1 ) are they indeed 4 1/2 feet deep ?
    2 ) is they area where you live silty soil or possibly low lying with fill brought in for house building.?

    The idea of the piers being the size and the depth they are to bear the weight of the deck structure as well to resist movement from frost heave. Depending on the soil conditions you may need a footing for the piers to sit on. The footings we use for these appilcations are those called " Big foot " which are wider at the base. The sono tubes are attached to them and when filled with concrete they become a monolythic component. The flared out portion of the " Bigfoot " provides the stability of dispersing the load but also helps to lock the pier down into the ground preventing heaves.

    I wouldn't think your house is moving as much as 6 inches .... if it were here would plently of cracks visable inside the home that would indicate hat.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  4. #4
    Join Date
    May 2009
    Location
    Wisconsin
    Posts
    4

    Default Re: Massive heaving on deck and patio in clay soil

    Thank you Canuk. Tha patio doors are on the wall exterior of the house. The house is not moving, just the deck moves at the posts up and down as much as 6". The deck is attached by a ledger board. I did some more investigating and dug down to the footing on my house and found what I think is ground water pooling under my house about 4' down which may be the cause of this. It may also be unstable soil. Would you still recommend the Big Foot footings? Any other ideas? Thanks.

  5. #5
    Join Date
    Jun 2009
    Location
    NY
    Posts
    35

    Default Re: Massive heaving on deck and patio in clay soil

    I recommend talking to a civil engineer in the area who is familiar with the soils. Installling a bigger footing will not solve this problem. You need to stabilize the soil in the area
    of the pier. Perhaps they can inject something into the soil. it is like a dock floating on a lake, Not an easy problem to solve.
    Or figure out some kind of drainage system to remove the water.

    http://www.westchester-architects.com

  6. #6
    Join Date
    May 2009
    Location
    Attleboro, MA
    Posts
    26

    Default Re: Massive heaving on deck and patio in clay soil

    Quote Originally Posted by DECK AND PATIO HEAVER View Post
    I had a deck built in 2006. The deck is over a walkout basement. Every winter the deck heaves in certain areas about 6" causing the upper patio door to pinch shut. The deck posts are on 12" diameter sono tubes and 4 1/2' deep (which according to the city I live in is below frost depth). Also, I had a patio and outdoor kitchen installed that also heaved 3+" causing damage to my siding on the house, pinched the basement patio door shut and now that spring is here, has not leveled out with the spring thaw. I have had 2 patios installed (1 concrete which was removed last year in favor of a paver patio). The new patio was set on about 18" of washed stone with a drain tile system to daylight with crushed limestone and the pavers on top. The kitchen area has pulled away from its retaining wall it was built against and the granite countertop has cracked in half. The kitchen was built on the original concrate patio so it only has about 4" of crushed road gravel underneath the slab. I am in desperate need of some advice on how to resolve this. There had been some water issues the past few years with city water junction boxes leaking. Could I have water from the city under my house causing this? What can I do? Any responses would be very appreciated. If you have any further questions, please ask!
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  7. #7
    Join Date
    Sep 2009
    Location
    uk
    Posts
    13

    Default Re: Massive heaving on deck and patio in clay soil

    I have known damaged underground drainage pipes cause this. Especially when work has been done in the area of works before. Maybe accidently or more often than not covered up on purpose from an uncompetent builder.
    Does any of the rainwater gulleys ever overflow?
    Last edited by sspaully; 09-10-2009 at 03:11 PM.

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