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Foundation Cracks: Causes, Crack Types, Repair Guide, and Tips

By Jacob L.

Cracks in the foundation of your home are scary to see, especially if it is a new house. Luckily, most cracks are harmless and do not pose a threat to the structural integrity of your building. In this article, you will learn what types of cracks typically appear in your foundation, the causes of these cracks, and how to fix cracks without the assistance of a professional.

 

What are the Causes of Cracks in Foundations?

Cause Description
Poor foundation construction Poorly constructed houses can lead to the development of cracks in their foundations. Using low-quality building materials is a primary cause of poor construction practices.
Soil conditions Soil impacts the stability of your house’s foundation. If moisture levels and clay concentrations are too high or low, the soil beneath your foundation can shift and bring about grave consequences.
Floods When water gets into your foundation, it causes damaging cracks. Periods of heavy rain and a variety of natural disasters can lead to flooding in your foundation.
Leaks Like floods, plumbing leaks can saturate your foundation with water and cause devastating cracks.
Drainage problems When water does not drain properly in your yard, excess water will pool near your foundation and cause cracking.
Gutters and Downspouts Water flowing off your house’s roof must flow off and into a proper gutter system, or else water will end up damaging and cracking the home’s foundation.
Evaporation During the hot summer months, the ground surrounding your house will dry up, causing the soil to set and sink. The shifting ground beneath the house’s foundation will consequently cause cracking.
Nearby vegetation Although you may like the look of trees beside your home, their roots absorb much of the moisture in the soil, causing the ground beneath your house to shift. Cracking will follow if the ground moves too much.

Poor foundation construction

Poorly constructed houses can lead to the development of cracks in their foundations. Using low-quality building materials is a primary cause of poor construction practices. Moreover, homebuilders that fail to test soil and compact that soil prior to construction can lead to foundation cracking later on. Indeed, soil compaction is important because the failure to do so will hinder the uppermost layer of soil’s ability to bear the weight of the future house.

Soil conditions

Soil impacts the stability of your house’s foundation. If moisture levels and clay concentrations are too high or low, the soil beneath your foundation can shift and bring about grave consequences. When moisture levels are too high in the soil, clay soil expands and pushes your foundation in an upward direction. But if the soil is too dry, it will begin to sell and shift beneath your foundation.

Floods

When water gets into your foundation, it causes damaging cracks. Periods of heavy rain, melting snow, and a variety of natural disasters can lead to flooding in your foundation.

Leaks

Like floods, plumbing leaks can saturate your foundation with water and cause devastating cracks. This is why you can’t overlook plumbing blockages and other issues of a similar nature that arise.

Drainage problems

When water does not drain properly in your yard, excess water will pool near your foundation and cause cracking. Outfitting your house and yard with proper irrigation and drainage can help prevent water from entering your foundation.

Gutters and downspouts

Water flowing off your house’s roof must flow off and into a clean gutter system, or else water will end up damaging and cracking the home’s foundation. Cleaning your gutters and downspouts will prevent blockages and the pooling of water near your foundation.

Evaporation

During the hot summer months, the ground surrounding your house will dry up, causing the soil to set and sink. The shifting ground beneath the house’s foundation will consequently cause cracking.

Nearby vegetation

Although you may like the look of trees beside your home, their roots absorb much of the moisture in the soil, causing the ground beneath your house to shift. Cracking will follow if the ground moves too much. This is particularly problematic during periods of drought in hot climates.

Is it Safe to Live in a House With Foundation Cracks?

While it’s hard to know without inspecting the house, lots of people live in homes with foundation problems that they know don’t even know about. Most people have nothing to worry about because homes built properly are very sturdy.

Indeed, total foundation failures, or structural collapse, don’t happen too often. If a building collapses, it’s usually because of a natural disaster and not because of the accumulation of cracks in its foundation. But this doesn’t mean you should simply ignore cracks in your foundation if you see them, especially because these cracks can worsen with time.

One small crack may not cost very much to repair, but several large cracks could end up costing you a fortune. Luckily, there are many affordable ways to do foundation repair.

Types of Foundation Cracks

Type of Crack Description
Horizontal cracks If you notice a large horizontal crack crossing the length of your wall, there is likely unbalanced soil and hydrostatic water pressing against your foundation walls. Horizontal cracks regularly occur alongside water leaks in the basement and an inward-bowing foundation.
Stair step cracks These types of cracks look like stair steps rising along the height of your walls. They are commonly caused by foundation settlement and sinking and moisture problems outside your foundation.
Hairline cracks These thin cracks stretch across your walls and are common in new buildings. Hairline cracks appear within a year or two of construction and are caused by drying and settling foundations.
Vertical cracks Vertical cracks are less serious than horizontal cracks, but you should nonetheless take note of them. They are caused by the settling of foundations over time or the natural process of concrete curing.

 

Diagonal cracks Diagonal cracks are similar to vertical cracks in the limited threat they pose to your building’s structural integrity. They are also caused by the curing or settling of concrete foundation walls.
Shrinkage cracks Shrinkage cracks occur when poured concrete foundations begin to dry and lose moisture. Newly-build homes are more prone to shrinkage cracks, but these cracks are not threatening to your foundation’s house. The biggest threat posed by shrinkage cracks is the opportunities they create for radon gas to leak into your basement.
Foundation slab cracks There are three primary reasons for foundation slap cracks: concrete curing, slab settlement, and frost heave. If the crack is larger than a hairline crack, your foundation may lose its structural integrity.
Non-structural cracks These types of foundation cracks do not pose a threat to the structure of your home and usually only cause water leaks during rainstorms.
Wet non-structural cracks When water evaporates from concrete, these types of cracks can occur. They usually appear within the first month after the concrete for the foundation is poured. The wetter the concrete mix, the higher likelihood of these cracks reappearing. These cracks are not particularly threatening to your structure.
Structural cracks This is the most serious type of crack because it poses a grave threat to the structural integrity of your building. Structural cracks are cracks in your walls and ceiling that are wider than ¼ of an inch. These cracks are caused by temperature changes, soil pressure, and soil shrinkage.

Horizontal cracks

If you notice a large horizontal crack crossing the length of your wall, there is likely unbalanced soil and hydrostatic water pressing against your foundation walls. Horizontal cracks regularly occur alongside water leaks in the basement and an inward-bowing foundation. Homes with block and poured foundations typically develop horizontal cracks.

In cold climates, horizontal cracks appear where the frost line is located and are often caused by the freezing and thawing cycle. As time goes on, the changing temperatures create unbalanced pressure on your foundation walls, leading to the emergence of horizontal cracks. Luckily, most horizontal cracks can be easily repaired by a professional foundation repair contractor.

Stair step cracks

These types of cracks look like stair steps rising along the height of your walls. They are commonly caused by foundation settlement and sinking and moisture problems outside your foundation. If you can fit objects larger than a quarter in the foundation crack, you should immediately call a professional inspector to assess the damage to your home.

Hairline cracks

These thin cracks stretch across your walls and are common in new buildings. Hairline cracks appear within a year or two of construction and are caused by drying and settling foundations. The good news for homeowners is that these cracks are cosmetic and do not pose a threat to the structure of the home. In fact, most hairline cracks can be fixed through DIY efforts that cost less than a few hundred dollars. Plus, the warranty of new homes usually covers these types of problems.

Vertical cracks

Vertical cracks are less serious than horizontal cracks, but you should nonetheless take note of them. They are caused by the settling of foundations over time or the natural process of concrete curing. Most repair guides call for the use of epoxy or polyurethane injections to fill the cracks. This DIY option should cost less than a hundred dollars. Again, if you can’t fit a quarter in the crack, the crack poses no immediate danger to your home.

Diagonal cracks

Diagonal cracks are similar to vertical cracks in the limited threat they pose to your building’s structural integrity. They are also caused by the curing or settling of concrete foundation walls. Like with vertical cracks, you can use epoxy crack injections to do DIY repairs. When you spot diagonal cracks, it is also useful to take a photo. You can then check back in six months to see if the crack has grown and decide whether or not to call a professional.

Shrinkage cracks

Shrinkage cracks occur when poured concrete foundations begin to dry and lose moisture. Newly-build homes are more prone to shrinkage cracks, but these cracks are not threatening to your foundation’s house. The biggest threat posed by shrinkage cracks is the opportunities they create for radon gas to leak into your basement. New home warranties will often cover the cost of repairing these cracks.

Foundation slab cracks

There are three primary reasons for foundation slap cracks: concrete curing, slab settlement, and frost heave. Concrete curing and settlement is the process in which a concrete slab dries, settles, and cures naturally. Frost heaves occur when foundations near the frost level buckle as a result of frozen water underneath the concrete slab.

If the crack is larger than a hairline crack, your foundation may lose its structural integrity.

Non-structural cracks

These types of foundation cracks do not pose a threat to the structure of your home and usually only cause water leaks during adverse weather conditions. Water leakage can ruin your belongings, basement walls, and floors, and it can produce mold. If your crack is less than 1/10 of an inch, it may be non-structural.

Wet non-structural cracks

When water evaporates from concrete, these types of cracks can occur. They usually appear within the first month after the concrete for the foundation is poured. The wetter the concrete mix, the higher likelihood of these cracks reappearing. These cracks are not particularly threatening to your structure.

When foundation cracks are wet and leaking, you can use urethane to seal them. This substance will expand inside the crack when it comes into contact with water. The faster you act with these cracks, the fewer foundation repairs you will have to do to your home.

Structural cracks

This is the most serious type of crack because it poses a grave threat to the structural integrity of your building. Structural cracks are cracks in your walls and ceiling that are wider than ¼ of an inch. These cracks are caused by temperature changes, soil pressure, and soil shrinkage.

Epoxy is the ideal material for repairing these cracks, but epoxy on its own is not usually sufficient to complete the foundation repair. You will generally need carbon fiber countersunk staples or straps for additional reinforcement.

How are Foundation Cracks Repaired?

There are several different ways to repair foundation cracks. The easiest method for small hairline cracks is to simply re-apply a thick coat of paint over the crack. For wider cracks, it is common to use a concrete crack filler and epoxy to conduct repairs. While these are repairs that homeowners can do themselves, sometimes professionals will be needed to repair bigger issues related to the overall structure of your home. Consult a professional for specifics regarding these larger repair jobs.

When to Fix Cracks in Foundation?

As previously mentioned, most foundation cracks do not threaten the structural integrity of your building. However, this doesn’t mean you should simply ignore cracks in your foundation if you see them, especially because these cracks can worsen with time. One small crack may not cost very much to repair, but several large cracks could end up costing you a fortune. Here are several clues that will let you know when you need to repair the cracks in your foundation:

  • Cracks that are wider than 1/10 inch
  • Cracks that become wider at one end
  • Cracks that continue to expand over time
  • Stair step cracks in brick walls
  • Horizontal foundation cracks
  • Several vertical cracks that appear near each other
  • Large, diagonal cracks
  • Cracks that appear across the ceiling and down a wall

While not all of these signs will mean that your house is in immediate danger, one or more of these signs should make you want to call an inspector to see whether repairs need to be done.

When to DIY Foundation Crack Repair?

Homeowners can repair most foundation cracks without the help of a professional, especially if the crack is smaller than half an inch wide and there are no additional problems with your foundation. Following the steps outlined above, you can easily purchase the necessary tools and materials needed to plug cracks in your concrete foundation.

How to Repair Cracks in Foundation?

While contractors will use slightly different methods to repair cracks in concrete foundations, most repair jobs follow a relatively similar process. These are the materials you will need: epoxy crack sealer, liquid concrete repair, plastic injection ports, and nails.

1. Check to make sure the crack is dry

Begin by checking the crack to make sure it is dry. If it is damp, you can use a blow-dryer to dry it out. Otherwise, if the crack remains damp, you should wait until it is dry before beginning repairs. As well, before attempting to repair the crack, scrub it clean of loose concrete, paint, or old crack filler using a wire brush and shop vacuum.

2. Block injection ports

Hammer 3-inch finishing nails partway into the crack, spacing them out by 12 inches each. These nails are important because you will use them to align the injection ports with the crack.

3. Mix epoxy sealer

Open your container of epoxy crack sealer and mix it using a clean putt knife. Blend the sealer until you reach a uniform gray color.

4. Attach the injection port

Take the sealer and spread it onto the base of one of the plastic injection ports, but be careful not to plug its hole. Next, slide the port over one of the nails in the crack and press it into the wall. Keep going as you install the remaining ports.

5. Spread sealer

Take the epoxy sealer and apply it to the entire crack using a putty knife or margin trowel. The sealer should be spread about one inch thick on either side of the crack. As well, you should cover the flange of each injection port with crack sealer until only the extended neck portion is showing. Finish by smoothing out the sealer.

6. Inject epoxy into the crack

Mix the liquid concrete repair using a plunger rod and then place it into a caulk gun. Beginning at the bottom injection port, squeeze the liquid concrete repair into the crack until it begins to ooze out of the port directly above.

7. Seal injection ports

After you finish with the caulk gun, plug each injection port along the crack.

8. Cut away injection ports

Allow the liquid concrete repair to cure for five days before cutting off the necks of the ports with a hacksaw. You can then patch the severed ports with a crack sealer.

When to Hire a Professional for Foundation Crack Repair?

Homeowners should be able to fix most foundation cracks by themselves. However, there are times when DIY efforts won’t suffice. If you find a crack in your foundation that is more than one-half of an inch wide, a professional should most likely take a look. When cracks of this size emerge, especially alongside other problems like bulging walls and uneven floors, there are likely more serious structural problems at play that require the expertise of a professional.

How Much Does it Cost to Fix a Foundation Crack?

For small repair jobs that require small amounts of epoxy, it will cost somewhere in the range of a hundred to a few hundred dollars. Bigger repairs that require professional assistance can cost between $2,000 and $7,500. Severe foundation problems that require construction crews can cost up to $25,000.

How to Prevent Foundation Cracks

Clean gutters and spouts

Clean out your gutters and spouts as often as possible to prevent them from getting clogged and leaking water into your foundation. The more water that pools around your foundation, the more likely damage will occur.

Improve landscaping around the foundation

Because water runs downhill, you should try to landscape around your home to stop water from flowing into your foundation. Indeed, gently sloping your landscape away from your foundation can prevent water from pooling and causing damage.

Fix irrigation systems

Obviously, you should ensure that your irrigation system does not lead to water entering your house’s foundation. Sprinklers should thus be positioned in a way that does not propel water toward your foundation.

Install drains where needed

If water tends to pool in various parts of your yard, install drainage systems to ensure that the water does not flow into your foundation.

Repair foundation cracks immediately

Finally, cracks in your foundation may not be troublesome at first, but they can threaten your structure if you wait too long to repair them. Make sure to crap your epoxy and fill those cracks as quickly as possible.

Final Thoughts

Cracks in your foundation are never fun to find. Luckily, most cracks are harmless and do not pose a threat to your house. This article should have provided you with a good idea of the type of foundation cracks that may appear in your home and the different ways you can go about fixing them. Most importantly, if you are worried about a rather large crack in your wall, floor, or ceiling, do not hesitate to call a professional!

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