Cracks on a Horizontal Foundation

Causes

• Cracks can be caused by a build-up of pressure against the side walls, which forces them inwards until they begin to crack under the strain. Shrinkage cracks occur in newly poured foundations, caused by the concrete shrinking as it hardens. These cracks are usually vertical, less than 1/8 of an inch wide and located in the middle third of the length of wall. A horizontal crack visible in the basement wall indicates that the foundation may be failing, most commonly because of the weight of the soil surrounding it. A vertical crack usually indicates settling of the house on the foundation, and may be serious if the house continues to settle.

Effects

• Inward bowing of foundation walls or a horizontal crack in your basement foundation wall due to lateral pressure are usually early signs of a failing foundation, which can eventually cause the walls to snap. This will result in a full or partial collapse of the foundation, endangering the home and the people who live in it. Settlement cracks, if they continue to spread after initial settling, may eventually lead to foundation collapse. Most of these cracks result in water entering the foundation, which can further weaken the support of the house.

Repairs

• Making repairs to a cracked foundation is complex and requires specialized knowledge as well as adequate tools and equipment, so you may need a licensed, professional builder to do the work. The builder will support the house with beams and post jacks while he removes the section of damaged wall and replaces it with fresh walling. The builder may also need to install drainage to remove the water and prevent it from re-entering the foundation.

Prevention

• Examine your home for indications that the foundation may be settling or sinking, such as tiny, vertical cracks in your basement walls. Water is the main culprit in foundation damage, so check the base of the house for downspouts and adequate drainage. Ensure that pathways don’t slope in a direction that allows water to flow back toward the foundation. Remove any plants, trees and shrubs located within 8 feet of the base of the house, and keep sprinklers at least 5 feet away when watering.