Sinking garage floor?

I live in a house in eastern Massachusetts. We have lived in the house for almost 14 years.

The concrete floor of the two car garage (which is directly under the master bedroom) is sinking in one corner (one of the corners where the garage meets the house). I would estimate that it has sunk more than six inches. This has been occuring gradually, but seems to have accelerated in the last year or so.

What to do? Does this present a structural risk to the house?



Some additional detail: the concrete floor is cracked as a result of the floor sinking, but I don't see any cracking of the walls, and the door from the garage into the house (12 feet from the sinking corner) is not warped in any way.

4 Answers

  • ?
    Lv 6
    1 decade ago
    Favorite Answer

    Your house is still safe. If your foundation was sinking also then you have problems. The concrete floor in your garage was poured separately. It sounds like the corner where it is sinking was not prepared right.

    We dig to make sure there is a hard pan base, (rock etc) then we bring in fill and compact it and water it (when the water no longer soaks into the ground, you know the base will be solid) We also use mesh under the concrete for strength. They did not put enough base material and compact it enough in that corner.

    Check for other cracks in your garage and basement floor. also the outside foundation walls. cracks indicate movement.


  • maeda
    Lv 4
    4 years ago

    Concrete Garage Floor Sinking

  • 1 decade ago

    It depends on how large the area is, and whether it's just the floor or the foundation too.

    If it's just the floor, you are probably ok...but why is it sinking? If it was not compacted right before it was poured, it should really be done sinking by now. Another reason would be that some kind of organic material was buried there...a stump, or waste wood from the building...and the decay will change volume over time, causing it to sink. If the fill had a lot of organic materials, like reclaimed swamp, that can shrink and settle too.

    If you are getting any cracking of your drywall, doors or windows that stick, those are signs of structural shifting. Wrinkles in siding and roofing are indicators, too. If the house is brick, look for cracking along the mortar joints, and the same on concrete block.

  • 1 decade ago

    does water run toward your house/ garage? the first answer is very good, but just a thought here, water could be washing out the base under the floor. as the floor gets lower more water runs under it and washes away more base. since it is at the corner where the garage meets the house i am guessing the gutter down spout is right there and doing the washing out. make sure the ground is graded so the water runs out away from the foundation and use splash blocks or a pipe to direct the rain water well away from the house.

    Source(s): siding and roofer
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