What Type of Cracks in a Block Foundation Are Bad?

There are many different types of block foundation cracks out there. Something to notice is that different types of cracks often foreshadow different potential problems you could be having. That means it’s a good idea to look closely and see exactly which cracks you’re dealing with. It could give you a hint as to the underlying problem.

Are you dealing with cracks? Match your block foundation cracks to one of these types. 

Horizontal Crack in Block Foundation

Horizontal Cracks:

These cracks typically mean that your home’s foundation is in trouble. More accurately, horizontal block foundation cracks appear because of significant pressure from the outside of the home pushing in on the walls.

When you see a horizontal crack, you should know that the next thing that could happen is the wall may start to bow inward. The hydrostatic pressure from outside the home will simply build to a point where it starts to bend the wall in on itself. If you continue to leave it to its own devices, the wall will crumble.

There are ways to fix horizontal cracks in a block foundation. However, you need to address the problem as soon as possible, so you don’t end up waiting until the wall collapses. If it’s catastrophic enough, that could take a significant part of the house along with it. 

Vertical Cracks in Block Foundation

Foundation Cracks - Vertical foundation crack in crawl space

What if the crack is vertical? Vertical cracks typically indicate that your home is settling overall. They generally mean that the home is settling more quickly or more substantially than it should, which can be devastating for your home in the long term.

One thing to note is that vertical cracks often grow over time. Not only do they grow wider, but they also grow deeper. As they do, they’ll eventually crack all the way through the foundation, allowing water to leak into the foundation area. That can cause problems all on its own as well.

Although vertical cracks typically aren’t an immediate concern, you should still talk to a JES expert as soon as possible to start work on repairing your home’s settling problems. You should also get more urgent help if you see vertical cracks appearing in more than one area. 

Stair-Step Crack in Block Foundation

Stair-Step Cracked Block

This stair-step pattern is most common in a cracked concrete block foundation or a brick wall. That’s because the grouting between the bricks offers a more “natural” place for the foundation to start cracking.

A stair-step pattern also indicates house settling, but in a different way than the vertical cracks. Typically, it indicates that the home is settling more on one side than on the other. When one side starts to shift more dramatically than the other, it puts excess weight on the other, which leads to stair-step cracks.

As with vertical cracks, this isn’t typically something to get help with urgently, but it still showcases problems that can lead to future structural damage, so it’s a good idea to consult JES. You should make your request more urgent if you start to notice the grouting falling out of the wall, or if the bricks in the foundation appear to be rotating out of place. 

Hairline Crack in Block Foundation

Vertical Wall Cracks

One type of crack you might not see as frequently is called a “hairline” crack. You can see hairline cracks in many different materials, and that includes your block foundation. These are called “hairline” cracks because they’re typically narrower than one-sixteenth of an inch, making them less wide than a strand of hair.

These are cracks that you often don’t need repair for. That’s because they’re so small, they often don’t show up if you have foundation problems, but instead just if you have shrinkage concerns.

Concrete shrinkage is a normal thing, so if you have a few hairline cracks, there’s not usually any need to worry. However, you may want to talk to a JES expert if you’re starting to see these hairline cracks form more than a year after the initial concrete pouring or if the cracks start to widen or deepen in any way.

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