Ground heaves up under deck in winter

  • Netguy
    Minnetonka
    Posts: 3197
    #1794992

    I know there is water not draining properly. Do I contact a foundation guy or landscaper?

    Eelpoutguy
    Farmington, Outing
    Posts: 10512
    #1794996

    Got any Pics of the area in question?

    Dusty Gesinger
    Minnetrista, Minnesota
    Posts: 2417
    #1795019

    Do you have gutters or downspouts to get water away from the area?

    gixxer01
    Avon, MN
    Posts: 639
    #1795026

    Landscaper can install draintile to move the water. A foundation guy will be better equipped to tell you if your foundation tile is plugged, ineffective or nonexistent.

    TheFamousGrouse
    St. Paul, MN
    Posts: 11718
    #1795066

    I’d want to know about 2 things. First, where is all the water coming from? No downspouts, sloping wrong direction, water pooling under deck, etc?

    Second, what kind of footings are there under the deck posts? How deep, what type, what size?

    Grouse

    Netguy
    Minnetonka
    Posts: 3197
    #1795606

    The attached picture is from last winter. Note the angle on the AC condenser.

    The house is a walkout with a 3-season porch and a deck that span the length of the house. I had the deck redone >10 years ago and the new footings (8 or 10 inch diameter concrete) are deeper than the original ones. The original footings allowed upward movement on the porch and deck. The new footings have upward movement on the deck. I have been insulating the footings with ~1 ½ foam the past several winters which has stopped the movement as far as I can tell. My concern is the ground between the footings and the house and the tilting of my new AC condenser last fall. Last winter I insulated the entire area under the deck and the ground still heaved an estimate 4 inches in the middle.
    For water control:
    • All the water from the back side of the house and the deck side of the porch comes out a downspout about 10 feet past the deck. I made my version of Under Deck to ensure this.
    • The garage side of the porch drips to the ground but drains to the outside edge of the porch.
    • The back side of the garage has a gutter and drains to the opposite side of the house/garage as the other gutter.
    • The water table can be high in my back yard as there is a creek near the back property line, about 100 feet from the deck/porch.

    Attachments:
    1. Under-deck.jpg

    Dusty Gesinger
    Minnetrista, Minnesota
    Posts: 2417
    #1795611

    High water table, bad soil, frost jacking. When the new deck footings were installed, did they wrap them with plastic?

    Netguy
    Minnetonka
    Posts: 3197
    #1795855

    No, the paper tubes.

    Eelpoutguy
    Farmington, Outing
    Posts: 10512
    #1795866

    Have an excavator or landscaper properly grade the area.
    You should have 6″ min clearance from siding to grade, then 6″ of fall at 10′ from foundation.
    Make sure roof discharge is properly diverted away from foundation.

    Remember – Last year was one of the worst for frost depth.

    fyi – 8″ to 10″ dia footings at first would seem to be a bit undersized. Haven’t seen anything that small in quite some time.
    But would need to know the size of deck and how many footings to do the calcs.

    Sometimes there is not much you can do to totally eliminate seasonal movement.

    Dusty Gesinger
    Minnetrista, Minnesota
    Posts: 2417
    #1795867

    Yes the cardboard sauna tubes, but wrap them in plastic before they go into the ground.

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