Foundations and Basements
Foundations
Donan Engineering has investigated thousands of foundation failures in residential, commercial, and industrial structures. Foundations are, of course, a building’s support to the earth’s soil. Settlement is the primary parameter when dealing with foundations. Many of our studies have been related to claims for original design and construction errors, product failures, storm and flood damages, vehicle impact damages, mine subsidence, earthquakes, and blasting vibrations.
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Photo 1 A failed mechanical connection on a buried 12-inch supply line beneath the pump station, resulting in the foundation soils being washed out from beneath it, which in turn caused the building to settle. |
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Photo 2 Water-saturated soils have resulted in the differential settlement of the foundation causing the stair-step crack beneath the window. The two most likely sources of water in a foundation are from inadequate perimeter ground slopes and from roof drains discharging too near the wall. |
Basement Wall Failures
Donan Engineering has investigated the cause and origin of thousands of basement wall failures in residential, commercial, and industrial structures. Many of our studies have been related to claims for original design and construction errors, product failures, storm and flood damages, vehicle impact damages, mine subsidence, earthquakes, and blasting vibrations.
The basement wall sustains the vertical load of the building and behaves like a simple beam supported at its top and bottom. It retains the earth’s lateral soil pressure and stops water intrusion into the basement. Cracks from lateral soil pressure in concrete block almost always take the form of horizontal cracks in the mortar joints. As the crack approaches the end walls, it decreases (in size?) and eventually stair-steps because the end walls offer horizontal support.
Typical Basement Wall Failure
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| Photo 1 Typical horizontal cracking in mortar joint. | Photo 2: Stair-step cracking at adjacent end wall. |
Wall cracks resulting from a bending failure are serious and should not be disregarded. Technically, as soon as the crack opens, the wall has failed, even though it has not yet collapsed.
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| Photos 3 and 4 |
Basement wall failure resulting from lateral soils pressures caused by too much backfill against an inadequately designed wall and poor surface drainage.
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| Photos 5 and 6 |
A backed-up city storm drain flooded the yard a few inches along the end of the house. The flooded water saturated the soils along the end of the basement wall causing hydrostatic pressure that rotated half of the wall inward at the corner.
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| Photos 7, 8 and 9 |
An overflowing creek resulted in 3 feet of flood waters quickly rising around this house. Hydrostatic pressure resulted in most of the basement walls collapsing.