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  • STRUCTURAL INSPECTION - Foundation Frost Heave

    I. Purpose of Investigation:

    At the request of the Contractor, a site inspection of recently poured concrete foundation
    walls was made on 6/18/02. Excessive cracking in two locations has become a concern.

    II. Description of Structure:

    The foundation consists of a residential basement, with an abutting garage foundation.
    8" poured concrete walls bear upon a strip footing. The basement foundation is
    approximately 4 feet below the garage foundation. The oveDrig required for the
    basement footing removed soil in such a way that the garage footing had to be terminated
    about 2 feet short of the basement wall. This 2 foot gap was bridged with 2x8 timber to
    support the wall concrete during the curing process.

    III. Observations:

    Excessive cracking was observed at the two locations where the garage and basement
    foundation meet. The crack pattern is consistent with soil heaving forces pushing up
    at the end of the garage footing. (See sketch). Recent weather included temperature
    ranges which could have taken the soil through freeze/thaw cycles. Because the footings
    do not have the typical 42" of frost protection, they are far more vulnerable to heaving
    forces.

    IV. Recommendations:

    Option #1:
    On each side of the garage, the cracked sections form a small region of wall which
    presumably can be removed and re-poured. The exposed jagged surface is good for
    bonding to the new concrete. It would be advisable to dowel into the existing wall
    with reinforcing bars. A specific design for this can be carried out if requested.

    Option #2:
    Pressurized concrete epoxy can be used to fill in the cracks, and bond the concrete back
    together. This should be done only by a contractor with the experience, equipment and
    training needed for this procedure. The epoxy contractor must determine if their
    procedure is suitable for this particular application. If the epoxy procedure is chosen,
    there will still be the problem of an uneven bearing surface at the top of the wall.
    Consideration for grinding this surface level must be made.

    For either repair, the exposed conditions leading to heave still exist. It should be
    considered that the same cracking may occur, so long as the air temperature is ranging
    above and below freezing, or the clay soil is swelling due to moisture during the wet
    season. Option #1 has a better chance of success due to the ability of the reinforcing
    bars to hold the concrete together until backfill can be carried out, and permanent frost
    protection is in place.



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1200 Troon Ct. SE
Grand Rapids, MI 49546
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