Vertical cracks in foundations and concrete walls in the basement or under space can be a sign of serious issues. These small cracks may be the result of normal settlement or, possibly, differential movement due to varying humidity levels around or under the base. The location and direction of the cracks are essential to determine the cause. Most cracks shouldn't be cause for alarm, but it is important to evaluate them to ensure they are not a sign of a more serious issue.
Differential movement is usually due to inadequate drainage around the home, which can cause high pressure levels to press against foundation walls. A long horizontal crack near the center of the wall (vertically) may indicate pressure on the wall from the ground. A long diagonal crack may indicate base settling or lifting, especially if the crack is wider at one end. Concrete poured when the temperature is cold will have fewer shrinkage cracks than concrete poured when it is hot; and in general, the more water added when mixed for the first time, the more shrinkage cracks there will be.
They are typically constructed by pouring concrete into metal or wood forms, and then the forms are removed once the concrete has set or hardened. For example, concrete finishers can add too much water to the concrete mix to make it more malleable. This additional water dissipates or evaporates causing stress on the concrete that causes it to contract. Precast concrete walls are built off-site, trucked to the construction site, and then placed in place. If cracks appear soon after pouring the concrete base, it is possible that the concrete was mixed poorly or poured too quickly.
A cold joint is where a batch of concrete is poured and it has started to set or has hardened and then another batch of concrete is poured against the previous batch. A more massive vertical crack can occur when construction contractors improperly prepare concrete foundations and when the wall had poor steel reinforcement when workers poured concrete for the wall. Evaluating a crack in a concrete foundation wall is often different from evaluating a crack in a concrete block or brick foundation wall. Cracking cannot be prevented, but it can be significantly reduced or controlled by considering the causes and taking preventive measures. It is important to evaluate any cracks that appear in your foundation or walls to ensure they are not a sign of a more serious issue.
