Foundation Repairs

By Nancy Nichols, P.E. | August 4, 2021

Your building has cracked foundation walls.  Is the foundation settling?  Are the cracks structurally significant?  What’s the problem, what’s the repair, and how much will it cost?  Who can do the work?

Initially, Team Engineering performs an assessment of the structural significance of foundation problems and contributing factors.  If your home is constructed on a hillside, the foundation wall on the upslope side of the foundation, as well as the structure that bears on it, may be deflecting downhill.  Due to our hilly and mountainous landscape, our buildings are commonly built into the hillside.  While some foundations are constructed without consideration of this geometry and perform well, others do not.  It depends on the geometry of the foundation, strength of the wall, differences in height of soil behind the upslope and downslope walls (a.k.a., unbalanced backfill), and drainage.

When the structural integrity of the foundation is deemed compromised, it must be repaired.  But when?  While foundation concerns generally do not develop rapidly, the rate of movement often increases over time.  Monitoring of the movement can give an indication of when repairs should occur.

For the repair of a leaning and cracking foundation wall that is deflecting downhill due to sizable unbalanced backfill and other conditions, the repair concept includes installation of tie back anchors.  The type of anchor will depend on soil conditions and site features. Due to the prevalence of large cobbles and boulders in New Hampshire soils, deadman tie backs are commonly installed.  This is a metal rod with a plate on its embedded end and a plate on the face of the wall.  Putting tension on the rod results in a retaining force on the wall face plate.  This retaining force resists the lateral soil pressure acting to push the foundation wall downhill. The cost of installation of deadman tie backs depends on factors such as number and length of anchors to be installed, access to the soil behind the wall, type of soil, and type of foundation wall.

There are numerous reasons why foundation walls do not perform as intended and a variety of solutions.  The solution needs to appropriately match the situation. We can give you the benefit of our experience assessing structural significance, extent and timing of repair, concept or design of repair and ballpark costs.

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