When Are Basement Cracks a Problem? 10 Types of Cracks You Should Know About!

What to do when you find relatively new foundation cracks in basement? How do you identify the cause of the cracks and find ways to fix them? This blog will guide you through the complete process of identifying basement cracks and what to do about repairs.

Concrete is one of the building blocks of the architecture industry. We use it for commercial and residential buildings to build walls, floors, dams, walkways, etc. In fact, it’s everywhere in our daily lives as we consider it a reliable material.

That said, concrete is not robust. It’s a porous material that can easily be penetrated by water. If there is enough pressure on the structure or if leaks occur, the foundation starts cracking. For residential properties, it becomes more problematic if the foundation leaks, especially in the basement area, are not identified on time. The delay could harm the residents and lead to further deterioration of the concrete structure.

Therefore, foundation cracks should be checked immediately to find out the real cause of the problem and fix it accordingly.

Types of Foundation Cracks in Basement

Identifying the cracks is as important as repairing them. You won’t be able to save the foundation of your property otherwise. Here are the types of basement cracks that you should know:

Horizontal Cracks

Horizontal cracks are serious as they are caused by hydrostatic water pressure and unbalanced soil affecting the foundation. If you notice foundation leaks in the basement and the foundation leaning inwards, then it’s due to the horizontal cracks.

Although horizontal cracks can occur anywhere, they are very common in colder areas. Due to the constant freezing and thawing cycle, these cracks occur in the foundation and harm the structure. If left untreated, horizontal cracks create unbalanced pressure on the basement walls.

Vertical Cracks

Vertical cracks are not as serious as the horizontal foundation cracks in basement. Therefore, there is no serious threat to the structure. There can be a few reasons for vertical cracks, but the most common ones are the concrete curing process and foundation settling.

As the concrete naturally settles and becomes harder over time, it can cause vertical cracks running up and down the wall. The same thing happens if the foundation does not settle well. Unlike horizontal cracks, vertical cracks do not require professional help. You can buy a DIY kit and fix the crack yourself using epoxy.

Stair Step Cracks

Stair step cracks start along mortar joints and become a threat to the foundation of any concrete structure. If your residential structure has block foundations, then stair-step cracks are imminent. There are two major causes of these cracks.

The first one is moisture-related. When the weather is too moist for the structure, you will see stair-step cracks in the foundation. The other reason is the foundation itself. If the structure is not sturdy and there is sinking in one or more areas, you’ll notice these cracks.

Hairline Cracks

Hairline cracks are common, so people usually do not worry about them too much. They are caused within a year of foundation as it settles and dries. All new constructions around the country have to face this problem. However, it is not dangerous to the overall structure of the house.

Hairline cracks can easily be fixed without professional help. You can begin a basement cracks repair DIY project to fix these cracks by spending a few hundred dollars. If you do not wish to repair it on your own, there’s always an option to hire a professional person for the job.

Diagonal Cracks

Like vertical and hairline cracks, diagonal cracks are harmless to the structural integrity. They are similar to vertical cracks except for a difference of 30 degrees in alignment with the basement wall. As the concrete becomes hard over time and the foundation settles, these diagonal cracks appear.

Epoxy crack injections are enough to fix these cracks. You can buy a $75 DIY kit to repair the cracks yourself or opt for the professional option if you can spare more money on the repairs.

Foundation Slab Cracks

Despite the different kinds of cracks, there are some basic causes for most of them. Foundation slab cracks are no different. With poured concrete slabs, it’s normal to think that the foundation cracks in basement are posing a threat.

However, if the reason is as simple as the natural curing of concrete, then foundation slab cracks are not dangerous. Besides the concrete settling and curing, there are some other non-threatening reasons like slab settlement issues due to poor soil conditions or workmanship and frost heave.

Shrinkage Cracks

When poured concrete dries and loses its moisture, it results in shrinkage cracks. They are similar to hairline cracks and start appearing within the first year of construction.

They are like vertical cracks and do not threaten the structural integrity of the foundation. However, if the property is located in an area with Radon Gas, then the high levels of the gas will pose a great risk to the basement. The gas can leak into the basement causing damage to the structure and leaving harmful side effects for humans.

Non-Structural Foundation Cracks

These types of cracks result in foundation leaks after the snow melts or during a rainstorm. Non-structural foundation cracks are not harmful to structural integrity. But the water seeping can lead to future problems for the basement.

Water can leak through the cracks and damage personal belongings, floors, and walls of the house, leading to a mold buildup. If these cracks are avoided, the non-threatening situation will become more serious. You should ask fast and get your basement repaired as soon as you notice the cracks.

Wet Non-Structural Cracks

These cracks occur soon after the foundation is poured and the concrete starts drying. When the water is evaporated from the structure, it results in foundation shrinkage. If the concrete mix was too wet, there will be more shrinkage, leading to more cracks.

Factoring in the natural concrete curing process, you’ll notice the cracks in the foundation, giving way to water leakage. To repair the wet and leaking cracks, it’s useful to have sealant material like urethane. The substance is flexible enough to inject into the cracks.

Structural Foundation Cracks

Structural foundation cracks in basement are more serious compared to the previous nine types we talked about. They pose a threat to the structural integrity when the cracks are horizontal in shape and ¼ inches wide.

Causes of structural foundation cracks include soil pressure, soil shrinkage, or temperature changes. Epoxy is the go-to material to repair these cracks, but it’s not enough to fix the problem. You’ll need to hire a professional to provide reinforcement and prevent the cracks from expanding.

Causes of Basement Cracks

Foundation leaks in the basement

Like humans, architectural structures also age with time and show signs of wear and tear. The foundation has to bear the weight of imperfect constructions and pressure surrounding the house. It results in cracks and foundation leaks, which indicate the beginning of the damage. If these cracks are not repaired quickly, it can contribute to more serious difficulties.

It’s hard to imagine living in a place that is not structurally safe. Our houses are indeed built to withstand the effects of external factors. Yet, these cracks in the basement are unavoidable.

You can’t blame yourself for this structural problem as many causes contribute to the different types of basement cracks we mentioned above. Some of the most common causes are:

Soil Saturation

When basements are constructed, they need support using footings. These supports are placed at the bottom of basement walls, as they hold up the house. If the soil under these footings becomes saturated, it can cause cracks in the wall or floor of the basement.

Usually, foundations are built to bear the pressure of saturated soil and push the walls inward. This is what results in cracking. While basement cracks repair can be done easily, it’s not possible to fix the oversaturation of soil. Many causes like poor gutters, lack of underground downspout extension, or improper grading can cause the soil to saturate too much.

The Trouble with Plumbing

While soil moisture is a problem you have to deal with in terms of basement cracks, there’s another water-related cause that can lead to foundation leaks. Plumbing adds water to the underground area as it consistently comes in and out of the house.

When there is a blockage in one of the pipes, it leads to sewage leaking in the basement and results in foundation cracks. The first step is to stop the water usage and find the leak. After fixing that, it’s time to work on the cracks.


Yes, drought can cause cracks in the basement foundation too. With soil saturation, it’s easy to see how cracks would appear on the basement walls. A similar effect occurs when there is drought.

Oversaturation causes walls to bend inwards, while lack of moisture in the soil causes them to shift outward and settle. If you have planted close to the foundation of your property, you’d notice cracks in the basement due to drought.

Outdoor plants need moisture from the soil, and they search for it deep in the ground. It causes a lack of moisture in the soil, resulting in cracks in the basement.

Stress Points of the Structure

All basements have cracks that are not always serious. The concrete curing process and natural factors can lead to some harmless foundation cracks in basement that just frustrate the homeowner but do not harm the structure.

One of the major causes of these cracks is the stress points in the walls. When you install electric or gas lines, it weakens the concrete and results in cracking. You might also notice the cracks at the corners of your windows. When you hire someone to find the cause of the cracks in your basement, the first thing they analyze is the stress points.

Concrete Shrinking

When we were talking about various types of basement cracks, you got to know about the cracks that happen due to concrete shrinking. When concrete pouring is done incorrectly, it leads to major issues when the concrete dries. And cracks are just one of those problems.

Depending on the mixture and humidity levels, concrete dries in different ways. If there is an inconsistency in the poured concrete due to too much water usage, it leads to expansion when it’s being mixed and contraction when it dries. If the dried concrete cracks when it dries, you’ll have to deal with foundation leaks and structural damage.

Timing During Construction

What happens when the builder mixes a perfect concrete solution but it runs out mid-pour? Believe it or not, timing matters a lot in the construction industry especially when pouring concrete for the foundation.

If some of the concrete dries while the team is working on the next batch of poured concrete, it will cause cold joints to occur in between pours. The water will seep through those joints, which will affect the drying time, causing foundation cracks in basement.

Tips for Basement Crack Repairs

basement cracks repair

The basement walls and footings support the entire weight of your house and if anything happens to them, it can cause structural damage to the property. Therefore, if you have cracks in the basement, you must treat them as soon as possible!

Not all the cracks require professional help and you can fix most of them yourself using DIY kits for basement cracks repair. However, if the cracks are threatening the structural integrity of the property, it’s better to consult an expert.

Even if you plan to fix a crack yourself, it’s still a good idea to find a foundation contractor to look at the cracks in the basement and determine the severity of the problem. Once you know how much help you need, you can repair the basement cracks accordingly.  

Here are some useful tips to help you through the crack repair process for your basement:

Don’t Sweat the Hairline Cracks

Hairline cracks are normal near windows, doors, and basement corners. By now, you already know what hairline cracks are and how they appear in the basement, as we discussed in a previous section. So there is nothing to worry about.

They appear within a year of construction so it’s possible to panic when you first see these tiny foundation cracks in basement. However, you should know that the repair process is not that tough for hairline cracks. If the crack is literally hairline width, you can cover them using a coat of paint. Read the next tip to know what to do if the crack is more than hairline width.

Monitor the New Wide Cracks

If you find cracks in your basement walls within a year of construction and the width of the cracks is more than a hairline, you should wait before finding someone to fix the cracks. Monitoring a new crack before fixing it is more crucial to find out whether the crack will expand or not.

If you have to monitor a crack, you can mark the crack on both ends with a pencil and write down the date of the marking. Measure the widest point of the width and note it down.

You can check the crack on a monthly basis for several months. If it expands, you can hire someone to fix it for you. If it does not expand, then a DIY basement cracks repair kit would be enough.

Crack Wider Than 1/8 of an Inch? Seal It!

When the concrete shrinks or the house settles, you can see several cracks appear on the basement walls. They are usually ⅛ to ¼ inches in width and do not pose a risk to the structural integrity of the house.

Despite that, it’s a good idea to seal those cracks to keep them safe from moisture or radon gas. Repairing a foundation crack in basement of a width more than ⅛ inch is a DIY project. There’s no need to consult an expert if you already know that the crack has not expanded or changed in the past several months.

Foundation Wall Cracks of ½ an Inch

Large cracks in the basement walls might look harmful at first, but most of them are not. Still, it’s better to seal them up to avoid any consequences. You can call a contractor to inspect the foundation cracks in basement and figure out the structural damage.

If the foundation crack turns out to be a simple crack with no damage risk, you can fix it with a DIY kit. If it’s not a simple problem and poses a serious threat, let the professionals repair the foundation cracks.

Foundation Wall Crack with a Bulge

Foundation walls can have cracks that do not pose a threat to the structural integrity, like the ½ inch crack we mentioned above. However, there is a chance of having a crack with a structural problem. If you see foundation cracks in basement with an accompanying bulge, it indicates a serious structural issue.

Steel is used to reinforce foundation walls so that they provide a sturdy footing. If the property is situated on clay soil and the clay swells because of moisture or water, it puts pressure on the wall. This leads to cracking in the foundation. You should consult a contractor immediately to fix this problem!

Water Seeping Through Cracks

It’s not unusual for basements and crawl spaces to have dampness as they are located below grade. But you might also face problems with foundation leaks where water seeps through the cracks instead of just moisture.

This issue does not only pose a threat to the structure of the property but also becomes a risk factor for mold growth. There are a few ways to keep the cracks free of water. You can first seal the crack and prevent more water from entering the space.

The next step would be to divert the water from the cracks so that it does not further damage the foundation.

Horizontal Cracks Near Basement Floor

Basement walls are poured before the basement floor. The concrete of these two different types of basement structures does not bond completely. It leaves room for cracks, horizontal cracks to be specific.

These cracks can be ½ inch in width and do not pose a problem for the structure. There is the occasional moisture and smell which can be avoided by filling up the cracks. You can use caulk to fill the cracks up.

If the cracks are wider than ½ inch, you should call a contractor for basement cracks repair services.

Dealing with Horizontal Cracks

The difference between horizontal and vertical cracks is more than just the direction of the cracks. Vertical ones appear after the settling and can be treated easily. But horizontal cracks are trickier to deal with.

They are caused by hydrostatic pressure, just like wall cracks with bulges. These foundation cracks in basement can cause significant damage to the property’s structure. So, it’s advised to call a contractor as soon as possible.

There are many ways to stabilize a foundation that’s causing structural damage. You can ask the contractor for a professional opinion and decide on the solution that works best for your house’s foundation. Generally, hydraulic lifting, underpinning the wall with steel, or excavating around the wall are the methods contractors use to fix this problem.

Wrapping It Up!

With the help of this blog, you now know everything about basement cracks, their causes, and ways to fix them effectively.

Cracks can be harmless or cause a serious structural problem to your property. What you should do is pay attention to the cracks you see on your basement walls and follow our tips to address repairs accordingly. Knowing the types of basement cracks and finding the right method to fix them is crucial to maintaining your basement’s structural integrity.