Foundation Cracks: When To Worry

Foundation Cracks: When To Worry - Image 1

You noticed a crack in your foundation, and you're wondering if it's a serious problem. Is this normal? Is my home okay? Should I break out the caulk and get to work??

Unfortunately, the answer to these questions is not a simple yes or no. It all depends on what type of foundation you have. 
In this post, we outline the most common types of foundation cracks you may find on your foundation walls. We'll explain what's normal, what's not, and when you might want to raise an eyebrow or two. Let's get… cracking (sorry... we had to).

Step one: Identify your foundation type

Slab-on-grade foundation

Slab-on-grade foundation

Block and base foundation

Block and base foundation

Pier and beam

Pier and beam foundation

Basement foundation

Basement foundation

Different foundations have different challenges due to the materials used in their construction. When you find a foundation crack, the first thing you need to do is figure out what kind of foundation you have. If you are unsure, here's a guide:

slab on grade foundation during construction

Slab on grade foundation during construction.

1. Slab-on-grade foundation

A slab-on-grade foundation is a concrete slab poured on a prepared lot. It hangs out on the soil surface without a lot of underground support, as there’s no basement or crawl space beneath the home.

2. Crawl space

There are two types of crawl space foundations:

  1. Pier and beam. This type lifts the home about one to three feet off the ground. In this setup, the space between the ground and your house is called a crawl space. Pier and beam foundations have a concrete beam deep in the ground around the entire house's perimeter. In the crawl space, you'll find additional support piers strategically placed to bear the weight of the home. 
  2. Block and base. Similar to pier and beam, block and base foundations also elevate the home above the ground by about one to three feet. However, these foundations do not have a concrete beam around the edges. Instead, support piers are spread out around the perimeter and middle to hold up the weight of the home.

3. Basement

This type involves a full underground level beneath the house. Builders dig a bowl-shaped hole, pour a concrete slab for the floor, and build the basement walls. In new homes, these walls are usually poured concrete or blocks, while older homes are typically bricks or stones. 

Basement foundation during construction

So why does the foundation type matter when it comes to cracking? 

Well, each foundation type has varying levels of soil support and is constructed with different materials. For instance, a slab-on-grade foundation that sits on the top layer of soil with minimal underground support will experience settling differently compared to a basement foundation, which is buried 8 feet underground. And therefore, the cracks will look different.

hairline crack

Tiny vertical cracks are typically just surface-level and don't impact the structural integrity.

Step two: Identify the crack type

1. Small, vertical cracks

Thin, short, and usually vertical. These types of cracks are hairline cracks and usually nothing to worry about. When concrete cures, it shrinks and, oftentimes, cracks. Cracks like this don’t represent a structural weakness and usually don’t get worse over time. Keep an eye on them to make sure they aren’t widening as time goes on, and call a professional foundation company if you’re concerned

Thrasher tip: If you spot a hairline crack, see if a nickel can snugly fit in it. If it doesn't fit, no need to stress. Check it again in six months, and if it has widened or lengthened, give us a call.

2. Diagonal cracks

Diagonal cracks, usually at a 45-degree angle, are signs that your foundation is settling or undergoing some movement. When a poured concrete basement wall experiences stress, it often fails at the corners, leading to these diagonal cracks that typically start in the upper corners of the foundation wall.

Thrasher tip: If you have a diagonal crack, monitor the angle. Upward indicates upward movement, and downward suggests settling. Call your local foundation repair specialist or us for a free, thorough home inspection.

outdoor diagonal crack

Upward diagonal crack.

diagonal crack in garage

Diagonal crack in garage.

Diagonal crack in basement

Diagonal crack in basement.

diagonal crack

Downward diagonal crack.

3. Stair-step cracks

stair-step crack

Stair-step cracks frequently appear in foundations with masonry walls and are one of the most common structural cracks.

Stair-step cracks get their name from looking like a set of stairs. These cracks show up at a 45-degree angle and might stretch across several rows of bricks or blocks, forming a kind of stepped pattern. You'll often find them in walls made of bricks, stone, or concrete blocks. The cracks follow the lines between the bricks or blocks because those joints are the spots where things tend to give when there's some movement happening.

There are two common reasons stair-step cracks occur: 

  1. Differential settlement. This means one part of your foundation settles more than the adjacent parts. As a result, the walls experience uneven stress and start to crack.
  2. Moisture issues. The pressure exerted by saturated soil creates movement and causes cracks to form along the mortar joints. 

Thrasher tip: Place a transparent plastic sheet over the crack. Regularly check for condensation or moisture accumulating underneath. Any moisture indicates ongoing movement and will require a professional evaluation.

Horizontal crack on basement wall

Horizontal cracks like this are severe and can indicate a compromised structural integrity.

3. Horizontal cracks

Block foundation walls sometimes give in at the middle, creating horizontal cracks and bowing inward as the mortar joints break. If your house has a block wall foundation, keep an eye out for cracks running horizontally around the middle of the basement wall.

These cracks are a clear sign that your foundation is going through some serious stress, and it's a cause for concern. It's a good idea to reach out to a professional foundation repair company for an expert opinion on cracks like these. The good news is they can be permanently repaired.

Thrasher tip: Place a pencil in the crack to gauge any width changes. If the pencil falls in deeper, it suggests it's widening. Reach out to a professional foundation specialist as soon as you can.

4. Cracks near windows & doors

If you spot a crack near the corners of windows and doors, it could mean your foundation is settling or shifting around.

These spots are sensitive to stress because when your foundation settles, the framework of your home, like the doors and windows, can get misaligned, leading to the formation of cracks.

Thrasher tip: Use a door-frame level to check for misalignment.

window crack

Downward crack near window.

crack in doorway

Horizontal crack near opening.

crack near window

Crack near window.

crack near door

Upward crack near door frame.

5.  Bulging or bowing walls

Bulging or bowing walls might not be cracks in the traditional sense, but they still point to some serious structural stress. These issues are often linked to sideways pressure from the soil (P.S. we wrote a great blog all about this pressure and the science behind it). 

Thrasher tip:  Press painter's tape along the bulge to track movement. If the tape stretches or breaks, this suggests ongoing stress. Reach out to a foundation specialist ASAP. 

rendering showing soil putting pressure on basement walls

Saturated soil exerts pressure on the wall, causing it to bow.

wall that's bowing inward

An example of a wall bowing inward.

What causes foundation cracks?

Foundation cracks can happen for a lot of reasons, and understanding them helps tackle and prevent issues. Here are a few common causes of foundation cracks:

  1. Foundation settlement. Over time, the soil beneath a foundation may settle or shift, leading to uneven support. This settling can make the foundation crack as it adjusts to changes in the ground.
  2. Soil expansion. Certain soil types, like expansive clay, can expand and contract significantly with changes in moisture. This movement puts pressure on the foundation, causing cracks.
  3. Poor soil compaction. If the soil beneath the foundation wasn't compacted well during construction, it may squish down over time, causing uneven settling and cracks in the foundation.
  4. Hydrostatic pressure. Imagine your home dealing with bad drainage or heavy rainfall. Excessive water can pool around the foundation, soak into the soil, and make it expand. This increased pressure can force water into the foundation, resulting in cracks as the home tries to handle the extra stress.
window not opening

Doors and windows can get misaligned and become hard to open.

How serious are foundation cracks?

Foundation wall cracks don't magically disappear; they actually tend to get worse over time. The tricky part is, they do it so slowly that you might not even notice them growing. It's easy to forget about them. But here's the catch: if you let these cracks keep expanding, there's a risk that the whole foundation wall could eventually fail, leading to a very messy, very expensive situation. 

Now, if your basement wall is showing some cracks, it might be causing issues all over your house that you didn't connect at first. Things, like windows sticking, floors sloping, and ceilings having gaps, can all be linked to a foundation that's sinking or settling. This means fixing your foundation might solve other problems throughout your home – or at least stop the damage from continuing.


When to worry

Not every crack in your foundation is an immediate red flag, but there are signs to watch out for that could signal a serious problem. Here's what to look for:

  • If the crack is wider than 1/8 inch (about as thick as a nickel).
  • Horizontal cracks are more concerning than vertical ones.
  • Stair-step cracks in bricks or blocks, especially if they’re widening over time.
  • Diagonal cracks indicate ongoing movement.
  • Multiple cracks can signal a widespread problem.
  • If doors and windows refuse to close properly, your foundation might be trying to tell you something.
  • Uneven or sloping floors.
  • New or expanding cracks.
  • Water leaks through foundation cracks are a definite cause for concern.

What to do about foundation cracks

Dealing with foundation cracks can vary based on the severity and underlying cause. The good news – you've got options!  

1.  Examine the size, location, and characteristics of the crack

The first step is to use the knowledge from this article to figure out what's going on in your world. Which way is the crack heading? Is it a big crack? Can a nickel squeeze in? Ask yourself these questions. And then check for other signs of foundation problems we mentioned in the section just before this one.


man pointing at wall crack

A visual representation of you monitoring the cracks. 

2. Monitor the cracks

Now, if you're not ready to reach out to us or any other foundation companies, you can monitor the cracks on your own. Wall cracks progress slowly, and chances are, your wall won't completely collapse if you give it a little time. Grab some measurements to keep tabs on any developments, and don't forget to follow our measuring tips for each crack style (you know, the ones we laid out above – just in case you missed that part...).

If you decide to keep an eye on the cracks before getting a pro involved, we recommend snapping a pic of the crack with your phone. It helps you note the date and makes it easy to see if there's been any changes over time.

3. Address water issues

Sure, you can't make the crack disappear. But you can help prevent it from getting worse. Most foundation issues are water-related and tied to poor drainage around the home. So what can you do? Clean those gutters, make sure the downspouts are channeling water at least 10 ft away from your home, invest in gutter guards, and check for any pooling water around your foundation after rain. 

If you find any issues, address them ASAP (and hey, we can help with that, too).

4. Consult the professionals

Now, let's get real. This is the part where we strongly suggest giving us a call. Not because we're all about that "money, money, money," but because we genuinely want to save your sanity and protect your home. Foundation issues are a double whammy: a lot for you to handle and a serious threat to your home's stability. 

Bringing in a foundation repair expert is the smart move. We're not here to speak for all the other folks in our line of work, but we visit your home, conduct a thorough inspection, break down the soil dynamics (the fun stuff) and then offer up a range of solutions at different price points. We're here to find what works best for you and your home. And hey, if there are no foundation issues, we'll let you know that too.

What is foundation repair?

house with helical piers and push piers

Push piers and helical piers may seem alike, but there's a key difference. Helical piers, seen on the right, resemble screws, while push piers, on the left, are pushed into the ground using hydraulic force to reach stable layers (in simpler terms, a cool machine pushes these steel rods down).

Foundation repair involves addressing structural issues or damage to your home's foundation. It stabilizes and strengthens the foundation, prevents further damage, and ensures your home is safe and stable. Here are some methods we use for foundation repair (and why):

  1. Helical piers: These are like screw-like supports twisted into the ground. They provide support and lift the foundation back to its original position.
  2. Push piers Strong steel pipes are driven deep into the ground until they reach stable soil, like bedrock, to support your home.
  3. wall anchors rendering

    Wall anchors are installed into a stable layer of soil away from the home. They link to steel plates on the inside of the wall using long steel rods. They hold foundation walls in their current position and tighten overtime to straighten the wall.

    Wall anchors: This system helps fix walls that are tilting, sliding, bowing, or buckling. It involves earth anchors embedded in stable soil away from your foundation wall, connected to steel anchors with long rods. When tightened, the anchors hold the wall securely in its current position.
  4. Wall braces: Wall brace systems use steel beams to support failing walls and restabilize the home. There are two systems available: PowerBrace involves steel beams secured against your walls, floor, and floor joists, tightening over time to reverse wall failure. EverBrace is for more severe wall failure, using steel corrugated panels, steel beams, and structural foam to create a new load-bearing wall and transfer the load off the failing wall.
  5. Carbon fiber: This system helps fix walls that are tilting, sliding, bowing, or buckling. It involves earth anchors embedded in stable soil away from your foundation wall, connected to steel anchors with long rods. When tightened, the anchors hold the wall securely in its current position.


When in doubt, call a professional

Now that you've learned about foundation cracks, the next step is to determine the best thing for you and your home. Are you ready to reach out to a professional foundation repair company, or do you prefer a temporary solution for now? The choice is yours.

And hey, nice to meet you! We didn't introduce ourselves earlier, but we're Thrasher Foundation Repair, a foundation and basement contractor with almost 50 years of experience. When it comes to foundations, we've got the know-how. If you happen to be in our service area, we’re here to help with any foundation questions, cracks you're seeing in your home, or even just chatting about life – we’re up for that, too. You can reach out to us by calling us at 1-800-827-0702, filling out this form, or starting a chat in the bottom right-hand corner. 

Article Categories:

Related resources

How to Identify and Repair Bowing Foundation Walls

June 7th, 2024

How to Identify and Repair Bowing Foundation Walls

Bowing and cracking basement walls can cause a lot of pressure! Read this article to learn how to spot warning...

Read more
What is the difference between Helical and Push Piers?

June 4th, 2024

What is the difference between Helical and Push Piers?

When looking into foundation repair solutions, two methods seem to be the most popular, helical piers and push piers. But...

Read more
Denver Soil Composition: How To Protect Your Home

February 6th, 2024

Denver Soil Composition: How To Protect Your Home

Learn about Denver's soil composition and learn essential tips to protect your home's foundation. Understand how Denver's soil types, from...

Read more
Why Your Basement Leaks & 5 Easy Ways To Fix It

July 26th, 2023

Why Your Basement Leaks & 5 Easy Ways To Fix It

Discover the most common causes of basement leaks, including hydrostatic pressure, wall cracks, poor sealing, and window flooding, while providing...

Read more