Wider cracks at one end. Water seeps into the basement through a vertical crack. You need to worry about a crack in the base when it appears as a horizontal fracture that widens or as an uneven division of steps in the mortar. Fine, vertical cracks are usually benign, while horizontal and stepped cracks often suggest compromised soil conditions and require immediate attention.
Cracked foundations can lead to structure problems, roof problems, problems with doors and windows, and even leaks in basement walls. Correcting structural and foundation problems can be very costly and sometimes cracks in the foundation will be a warning sign of other structural problems in a house. Concrete can crack over time, often early in its useful life, as it cures and shrinks. Therefore, if you find a short, often vertical, thin crack in the wall of your foundation, especially if it occurs near the seam where the forms for the initial pouring of the foundation were joined, it may not be a cause for concern.
Cracks in the walls of foundations of this type usually do not represent a structural weakness that may worsen over time. However, if you are concerned about fine cracks, we would be happy to take a look at them as part of our free, no-obligation inspection. Now that you know that a crack in the base is just a fact of life, let's see when to worry about them and when is it time to repair some crack in the base. Horizontal cracks mean a major rupture of the wall due to external pressure.
Vertical cracks, when they are wider at the top, indicate a drooping base and a shaken center, and when they are wider at the bottom, they usually mean a lowered base and a descending center. Perspiration draws water out of the soil, and this drying of the soil causes it to compact a little, resulting in the downward settlement of the foundations. There are harmless cracks, inevitable cracks and severe cracks, but the fact is that any cracks in the base can indicate serious and expensive problems, which means that you should not ignore even one of them. Freeze-thaw cycles or hydrostatic pressure usually cause these cracks, which occur when rain water or snow (as it melts) from outside pushes against the foundation.
Of course, flooding is the most common cause of foundation damage, so be sure to check your home if you've been through one recently. This can be done by removing foundation plantings, installing gutters and downspouts, and adding soil to the yard along the foundation to create a slope of 2 percent or more away from the house that allows water to escape naturally from the foundation. Usually, this will lead to longer diagonal cracks emanating from the corners of the foundation wall, usually in the upper corners. While the crack must be sealed as described above, it is even more important to keep water away from the base wall.
Angular cracks will often occur in the upper 12-16 inches of brick walls laid directly on a concrete base. Newer houses often have foundation walls built from poured concrete and reinforced with steel bars. If the crack location is where the foundation wall meets the basement floor and is no more than half an inch wide, it must be sealed, but it is not likely to be a structural problem. A slab base above ground is built by removing the top layer of the soil, leveling the ground and pouring concrete on top.
Repairing a crack in the base in this width range is a simple DIY project that involves filling the crack with a putty that is compatible with concrete, such as Dap concrete and mortar sealant. Both types of foundation cracks are signs that your foundation wall is losing the battle with hydrostatic pressure. And if it turns out that you don't have a foundation problem, we'll be happy to give you that good news too. Cracks over a door or window can indicate expansion and contraction of materials and are not related to foundations, certainly something to watch for, but not a foundation problem that requires urgent attention.
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