How Can I Tell If a Crack in My Wall Is Serious?

Marwa Hasan
Written by Marwa Hasan
Updated August 16, 2021
Woman putties at crack in wall
Svyatoslav Balan - stock.adobe.com

Catching a wall crack before it becomes a major issue will save your home and your money

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Have you noticed a recent crack in your home? 

Before you panic, most cracks are harmless, and they happen in almost every house, even in new builds. A hairline crack is simply a sign that the house is settling, which is purely cosmetic and can be easily fixed with putty and paint. 

However, if you notice some serious cracks on your wall that are large, long, or in certain key areas of the house, these can be signs of structural or foundation problems that require the intervention of a professional. They will be able to inspect the wall and confirm if any cracks are critical. 

Still, you might be able to examine the crack yourself to determine whether it’s a sign of structural damage. Look out for these warning signs.

1. Wide Cracks

Typically, wider cracks indicate more critical issues than thinner cracks. Measure the cracks with measuring tape; cracks that are quarter-of-an-inch wide and larger are often more serious than smaller cracks.

A one-inch-wide crack or a crack that allows daylight to come into your home means the wall is severely damaged, and it could be a sign of subsidence or structural damage.

2. Horizontal Cracks

The direction of how the crack runs on the wall can help determine whether it’s alarming or not.

If the crack on the wall is horizontal, it might mean there’s a problem, such as severe foundation shifting or water damage. 

Long, horizontal cracks that extend between interior walls and ceilings generally signify roof truss issues, which can cause ceilings to detach from walls. 

A concrete basement wall with a horizontal crack mid-height needs to be monitored to see if the size of the crack changes. If it does, a structural engineer’s review is recommended. If you inspect your foundation and notice a serious-looking crack, you should get professional help.

3. Vertical Cracks

Vertical cracks in concrete walls typically indicate foundation movement. Vertical cracks that are an eighth-of-an-inch wide or larger could be a sign of problems and may need a review from a pro. 

Some normal cracks in plaster walls get worse in time, so before grabbing your putty knife to repair cracks straight away, you should wait a while to see if they show any development. If cracks rapidly get bigger in length, wider, or change in any way, they may present serious issues. It's best to hire a structural engineer to inspect them.

4. Diagonal Cracks

A diagonal crack that appears in the wall, which can be wider at the top and tighter at the bottom, is usually caused by the foundation settling. A crack that runs at a jagged 45-degree angle is almost always a shear crack.

Some cracks start at the top of the concrete basement wall and move diagonally down to a corner. This is usually accompanied by inward tilting of the top of the foundation wall. The earth pushing against the basement wall can cause this type of crack.

If you are experiencing these on your wall or basement walls, a foundation repair pro should take a look at them.

5. Stair-Step Cracks

Stair-step cracks following the grout line between the bricks of your interior or exterior walls may be a sign of a structural issue in your property. The problem might be more serious if you have a complete separation in the cement between bricks or if the bricks are wiggling. If that's the case, call a foundation expert ASAP.

Stair-step cracks that appear at the corners of windows or doors generally imply settling or heaving foundations and may present pressing issues.

6. Nail Pops in Drywall

Examine the area surrounding the crack and look for nail or screw heads that might be visible on the surface of the wall. 

The nail or screw might have pulled away from the stud beneath the drywall. “Nail popping” is a common sign of an underlying structural problem, and you can see it with drywall cracks.

7. Wet Cracks

If there is water leaking into the crack or if there are white powdery stains, these could be cause for concern. If concrete, drywall, or plaster cracks feel damp, you may have a water infiltration issue that requires immediate attention.

8. Cracks in the Foundation Walls

Crawlspace foundation or garage foundation cracks are more affected by soils that expand and shrink during weather fluctuation. 

If the cracks in the foundation wall tend to open in the summer and close in the winter, then the foundation might need additional support. A structural engineer will assess the situation and give you a quote for the foundation repair cost.

Cracks that are a quarter-of-an-inch wide or bigger that run vertically in the basement or garage slab can be a sign of a failure of the ground below, and a review is recommended.

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