Reasons Why a Concrete Foundation Is Not Square

Installation Problems

• Concrete block foundations that are not square often trace their problems back to poor installation practices. Installing a concrete block foundation without first measuring the site and marking the ground can result in foundations that appear square but are slightly off when measured. At each step of the process, workers must measure the diagonal spans of the foundation and compare them to one another as well as design documents.

Problems With Mortar

• Concrete block foundations use mortar to attach the blocks to one another. If the mortar is mixed improperly or applied in uneven layers, it can cause a foundation not to be square when it is completed. Only experienced masons must work on a building's foundation, using the right materials and working only when conditions are right for the mortar to cure properly.

Improper Framing

• A poured concrete foundation uses wooden frames to determine the size of the concrete slab that will serve as the foundation. In some cases, such as large homes or those with irregularly shaped basements, the foundation will require several individual frames. Constructing each frame to be square and squaring individual frames to one another are added challenges in getting a square foundation. Here again, frequent measurement is necessary to check for squareness throughout the process.

Pouring

• Pouring concrete presents another opportunity for building a foundation that is not square. Even if the framing is perfect, builders must mix the concrete properly and pour it before it begins to harden. Using the wrong mix can cause concrete to leak out of the frame or contract as it dries, leaving an irregular foundation shape. Pouring a foundation also involves leveling the concrete once it is in place. Failure to do so will cause the surface to be sloped once it dries, throwing off the rest of the construction project.