When Should I Be Concerned About Cracks in a Slab?

Cracks in the floor of a concrete garage can be a sign of serious structural problems or simply a cosmetic issue. As homebuyers or homeowners, it is important to know when to worry about these cracks. Foundations can crack for many reasons, including unstable soils, poor drainage, and sedimentation. In the United States, approximately 60% of homes are built on soils with a certain clay content; of these, more than half of homes will suffer damage due to this clay content.

This movement of the ground is just one of the reasons why foundations crack or fail. Plastic shrinkage cracks are common in reentrant corners (corners that point toward the slab) or with circular objects in the middle of a slab (pipes, plumbing fixtures, drains, and manholes). When the top of a concrete slab loses moisture too quickly, cracks are likely to appear. While unsightly, these cracks are not a structural concern.

As the concrete dries, even after it seems hard, it acts a bit like drying mud and is filled with a maze of cracks. The important thing in temporary and permanent solutions is to prevent more moisture from entering the crack. Types of foundation cracks, crack patterns, differences in the meaning of cracks in different foundation materials, site conditions, building history, and other evidence of building movement and damage are described to help recognize foundation defects and to aid in separating cosmetics or hazardous conditions from those that are likely to be important and potentially costly to repair. After you have fixed all the cracks in the concrete, consider adding an epoxy layer to the garage floor. Welded wire mesh can also help reduce shrinkage cracking, but only if placed in the middle or top half of the slab, but at least 2 inches below the surface. If concrete is poured in colder months, assuming it is laid on a good foundation, it will have fewer cracks and smaller.

A concrete slab without reinforcement will generally have more cracks, and the cracks will be wider than the cracks of a reinforced slab. Early cracking may initially be considered as a minor deficiency; however, it is recommended that building owners and building maintenance managers appoint qualified corrective repair contractors to properly repair these cracks sooner rather than later to help extend the life of the concrete structures. Adding water to ready-mix concrete increases the likelihood of segregation and excessive bleeding, which will make the concrete surface porous, weak, and prone to cracking. Low-viscosity epoxy resin is mainly used for structural crack repair when future movements (latent cracks) are not anticipated. Control joints are designed to weaken concrete in certain areas so that concrete cracks in a straight line in these spaces.

Active cracks change over time, widen and move in various directions while inactive cracks stay the same.