What Causes a Wall to Bow?

Water

• When water freezes, it expands or takes up more volume. During the wintertime in areas where the ground water freezes, the expanding water in the soil will press against the foundation walls with great force, causing them to bow. Ground water that sits below the house's foundation will also press up from below, causing the walls to bow. Sump pumps and waterproofing the house's foundation will help decrease the damaging effect of ground water on the house's foundation walls.

Soil

• Soil applies a lateral force to basement walls. Certain types of soil, such as clay, will expand when they get wet, pressing against the foundation walls even more. If you see horizontal cracks along the foundation in your basement, your walls are not only bowing, but they are beginning to give way to the soil pressure. A foundation repair specialist can install equipment to repair the crack and prevent the wall from failing.

Poor Construction Quality

• The mason who originally constructed your basement walls may have cut corners or otherwise compromised the quality of the walls for a number of reasons. Placing a sill plate that is incorrectly sized for the wall, because the mason is in a hurry during construction, will place too much lateral pressure on the wall and will lead to cracking and bowing later. The mason may rush and refill the earth around the foundation too soon, not allowing the fresh concrete enough time to cure properly from direct exposure to the air.

Tree Roots

• When trees, especially those that are larger, grow near the perimeter of your house, the possibility exists that roots from those trees are pushing on the foundation walls. The force of the tree roots against the foundation will eventually lead to bowing in the walls. A tree does not need to stand right next to the house for the roots to press against the foundation since the taller the tree, the further the roots can extend through the soil.

Drywall

• Drywall can bow as well, although for a different reason. Drywall begins to bow when whoever installed the drywall did not drive enough fasteners around the perimeter of the drywall sheet. Without sufficient fasteners, the drywall sheet will develop cracks around its perimeter from bowing. If you only patch the cracks, the problem of too few fasteners causing bowing still goes unaddressed, and the cracks will form again. This same problem happens with drywall sheets on the ceiling, although the bowing becomes more pronounced.