What Causes Bricks to Crack on the Corner of a Home?

Environmental Changes

• Heat and humidity, or excess moisture can cause the soil, concrete slab, bricks and the wood frame to expand; cold and dryness causes the materials to contract. This repetitive movement is normal and should be expected to create hairline step cracks along the mortar as the home ages. When the cracks become large, have uneven width or cause breaks in the bricks, then further investigation is required to determine the exact cause and remedy.

Shifting Soil

• Minor shifts in the soil because of temperature and moisture levels is normal. However, extremes in the level of moisture and rapid changes cause the soil to shift, and concrete slabs may loose the underlying support. Once the soil moves from underneath, the weight of the house presses down on the slab, often causing the slab to break. If the home is built on a hill or the soil has a large amount of sand, be particularly attentive to erosion.

Vegetation

• Other dangers to a home's foundation and brick veneer are trees and shrubs. Watering shrubs and other vegetation around the home increases the water levels of the soil near the edges of the foundation, while the soil at the center of the footprint may remain dry. This creates an imbalance that can stress the concrete slab. Roots of trees planted near the home not only pull moisture from the soil, but their growth causes soil shifting. Tree roots that grow underneath the home may grow large enough to lift a portion of the concrete slab and compromise stability.

Weak Foundation

• If the cracks are horizontal, it could be a sign the foundation, typically a concrete slab, is unable to bear the weight of the home's construction. Horizontal cracks cause bricks to crack, and the cracks usually become wider and may reach from one corner to another. If horizontal cracks appear, immediately consult a professional.

Shifting Rafters and Frame

• A number of things can cause rafters and parts of the frame construction to shift, including the foundation. Step cracks or cracked bricks typically appear uneven, where a broken brick protrudes farther than its other half, or bricks at the top may lean outward or inward. Another cause of the bricks leaning outward is the lack of metal ties to hold the veneer to the home.