Different Types of Foundation Cracks

The first thing to know is that there are many different types of foundation cracks. These cracks all have different problems associated with them and therefore different methods of repair. Along with having the knowledge of the types of foundation cracks you should also know how their significance may change due to different factors.

These are some of the different types of foundation cracks you may run into, as well as a description of how to deal with them in different situations. 

  • Hairline

Of all different types of cracks, hairline cracks are usually the cracks that cause the least potential for problems. Hairline cracks are typically less than one-sixteenth of an inch wide and aren’t uniform or connected to each other.

For the most part, hairline cracks are just cosmetic and don’t present a structural problem. You may want to look for the actual reason why; most commonly, it’s due to concrete shrinkage, which isn’t necessarily a problem. However, if it’s due to spalling or improperly placed steel reinforcement, you need to address it immediately. 

  • Uniform

Usually, uniform cracks also aren’t a significant problem. These problems may also occur due to shrinkage. As long as you find them near the center of the concrete, rather than at the edges or extending to the bottom, they usually don’t showcase a serious issue.

When it comes to uniform cracks, one thing you should notice is how wide they are. Cracks that are wider than one-sixteenth of an inch but narrower than an eighth of an inch are unlikely to showcase a structural problem. 

  • V-Shaped

What if the crack is wider at one end than the other? These are “V-shaped” cracks, and they may be important to pay attention to.

The first thing to determine is which side is wider. Is it wider at the top of the crack or the bottom? Cracks that are wider at the bottom tend to showcase more of a structural problem than those that are wider at the top, especially if they’re in a concrete block wall or a brick wall.

Another thing to notice is the placement of the crack. If the crack is V-shaped, wider at the top, and doesn’t extend to or past the bottom of the foundation wall, it’s likely to be a shrinkage problem. Contrast that to a crack that is V-shaped, wider at the top, but extends past the bottom of the foundation wall, which is more likely to be structural.

Additionally, a V-shaped crack that’s in the corner to an adjacent opening could showcase structural problems. Pay close attention to the wall adjacent to the opening, because even an otherwise safe crack can mean the area’s experiencing structural issues. 

  • Broken Bond Courses, Bowing

You may see these cracks in brick foundation walls. The concept of “broken bond courses” happens when the grouting between bricks starts to crack.

These cracks typically happen either at the same time or just before you start to see bowing in the basement walls. If the basement wall is bowing one inch or further, you need to treat it as a serious problem. It can happen because of settlement, movement or thermal expansion, and can result in problems as serious as collapse.

Broken bond courses can also make other types of cracks more serious. For example, even a V-shaped crack that’s wider at the top and doesn’t extend past the bottom of a foundation wall can showcase serious problems if it’s in the brick bond. 

  • Stair-Step

It’s most common to see stair-step cracks in brick walls because it’s typically the easiest way for brick to crack. However, you may also see it in concrete block foundations. These cracks typically happen because the foundation is settling further to one side than another.

Although this doesn’t inherently mean that a foundation is on the brink of collapse, it does mean you need to pay attention to other signs of house settling. If pieces of the brick bond are falling out or the bricks appear to be rotating out, you should also look for other structural issues. 

  • Horizontal

There are many types of horizontal cracks out there. Horizontal cracks can mean a variety of things for the home’s foundation, but one of the things it most commonly means is that the wall is on the brink of bowing.

One thing you should pay attention to is where on the wall the crack is. If it’s low, near the bottom, it can be a sign of early foundation failure, and it probably indicates that the home requires additional foundation support. Mid-height often indicates wall bowing, and you may find water if the crack was caused because of hydrostatic pressure. Horizontal cracks in the upper third of the wall often indicate frost damage. 

  • Vertical

Vertical or diagonal cracks tend to indicate structural concerns. This is especially true if you see very significant cracks, but some areas may indicate structural problems even if they’re otherwise pretty small.

An especially important concern comes if you’re seeing vertical or diagonal cracks at the center of the header or the corners of the building. This can be seen in brick or concrete foundations. These can be some of the worst cracks because they typically indicate foundation failure, and you should pay attention to them immediately.

Another type of vertical crack to note is one that happens underneath a ground-level window. If the crack reaches from the window all the way to the ground, it could indicate structural problems, especially in the initial construction of the window.

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