Understanding Foundation Cracks and Knowing When to Repair Them

The best way to know how to repair foundation cracks is to understand why they happened in the first place. In this post we’re outlining the different types of cracks, how they form, and letting you know when they need to be repaired. In some cases, cracks in your foundation aren’t always a cause for concern.

Types of Foundation Cracks

Hairline Cracks

These nonstructural foundation cracks are generally vertical, and aren’t a cause for concern. These cracks include settlement cracks and shrinkage cracks. They are generally less than 1/32″ in width.

Especially in new construction homes, some cracking from settling is normal, and to be expected. More serious settlement can cause larger cracks, but so long as the cracks remain hairline, they aren’t a cause for concern.

Shrinkage cracks appear within the first few years of the home being built due to stress caused by the concrete shrinking as it dries. These are common and aren’t structural in nature. On their own, shrinkage cracks aren’t a cause for concern.

Vertical Cracks

These types of cracks run straight up and down, or within 30 degrees of vertical. Vertical cracks in walls usually appear due to concrete shrinkage if you have a newer home.

Even if your home isn’t new construction and vertical cracks appear, they are not usually a structural issue. However, over time, this type of crack will allow for water and insects to easily enter your home.

You will want to watch for any moisture, or a rusty looking discoloration in or near the crack. To repair a vertical crack, or make it water-tight, we will use a high-density polyurethane foam to fill in any gaps and voids within the concrete. In some cases, we will use other waterproofing methods throughout the rest of the basement if needed.

Diagonal Cracks

Diagonal cracks are caused by differential settling of the foundation. Differential settling can happen at any time, whether the house is new or old. This type of settling is caused by a change in the ground conditions underneath the footings, which is why one end of the crack will generally be larger than the other.

Diagonal cracks can be repaired using the same method we mentioned earlier. However, with diagonal cracks, more foam is typically needed to account for additional future movement.

Horizontal Cracks

A horizontal crack in the foundation is a structural concern. Horizontal cracks are a sign that your foundation is failing.

Because the foundation can no longer withstand the pressure and weight of the structure, it bows inward, causing the foundation to crack. These cracks will appear on load-bearing foundation walls, and develop below grade. In brick or cement block foundations, a structural crack may sometimes appear to be stair-stepped instead of horizontal.

When In Doubt, Contact a Professional

Once you recognize the types of cracks you see in your foundation, it is very important to watch them closely. Cracks that expand are another sign of trouble.

If the cracks are structural in nature, simply sealing the crack won’t solve the underlying issues. In that case, we might need to stabilize your foundation in order to prevent further damage. In many cases we install foundation underpinning products such as ECP steel piers to stabilize and fix failing foundations.

For any of your foundation crack concerns and foundation repairs, contact us!