Tips from the Inspector - Structural

FOUNDATION CRACKING

Probable causes and concerns:
Most foundation cracking is caused by shrinkage of the concrete during the drying & curing process. The key to determining the seriousness of foundation cracks is to check for signs of movement in the wall. If there are no signs of movement there is usually nothing to worry about.

Horizontal movement in the wall can be recognized by running your hand across the crack to determine if the concrete is uneven from one side to the other. When horizontal movement is present, the cause is usually a pressure from outside the foundation wall.

Vertical movement in the concrete wall is the most serious as it would likely indicate a broken footing. To identify this problem, imagine each side of the crack to be a piece of a jigsaw puzzle. The two pieces of the puzzle should be aligned horizontally.

Remedy:
Hairline cracks with no sign of movement can be filled with butyl caulking.

Cracks with signs of horizontal movement must be stabilized by alleviating the exterior pressure that has caused the movement. It may be necessary to lag bolt steel strapping across the crack to prevent further movement and then fill with butyl caulking or concrete patch.

Cracks with vertical movement require stabilization of the footing and possibly mud or hydraulic jacking if there is major vertical movement. This type of crack should definitely be inspected.

Cost:
Butyl caulking is cheap and economical to apply. Cracks with signs of movement in the wall must be assessed individually as to cost of repair.

Comments:
Most foundation cracks are of no concern and do not affect the structural integrity of the building. When signs of movement are present, it is not always a serious concern and should be assessed by a structural engineer. The key is to stabilize the wall and/or footings to prevent further movement.

CONCRETE FLOOR CRACKS

Probable causes and concerns:
Most concrete floor cracks are caused by shrinkage of the concrete during the drying process. Unless there are serious signs of movements or heaving, there is no need for concern.

Cost to repair:
These cracks are usually easily repaired with concrete patch for very little cost.

Comments:
It should be noted that concrete floors are not a structural component except with wooden foundation applications where the concrete pad acts as lateral support for the walls.

 

WET BASEMENT

Probable causes and concerns:

The most common cause of water entering the basement is improper landscape drainage near the foundation and under decks and steps.

Missing eaves troughs and inadequate downspout extensions are another common cause of water problems.

Occasionally, heavy rains over a long period will raise the water table to a level above the basement floor pad. A water table problem causes water to enter all around the perimeter of the basement floor, often where the concrete wall meets the floor pad, and through hairline cracks.

Remedy and Costs:
Leakage caused by landscape taper or eavestrough/downspout extensions are easily and economically repaired.

Water table problems can usually be remedied by the installation of a sump pump which will cost $600.00 to $800.00 installed. Sump pumps are a positive feature as properties that have never had a wet basement can suddenly be the victim of a rising water table.

Comments:
It should be noted that concrete is not water proof and that if water is allowed to pool near the foundation wall it eventually will find its way into the basement.

Small foundation cracks do not cause basement water problems and filling these cracks will not stop water problems. The source of the water must be found and remedied.

It is seldom necessary to excavate and water proof a basement to solve problems. This is a very expensive undertaking and seldom successful on its own.

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