Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.
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The vast majority of foundations throughout the U.S. are constructed using poured concrete or concrete masonry. While these materials are excellent choices for foundations, they tend to shift, resulting in a dreaded foundation crack.
You should worry about a foundation crack when it appears as a widening, horizontal fracture or as a jagged, stairstep split in the mortar. Thin, vertical cracks are usually benign, while horizontal and stairstep cracks typically suggest compromised ground conditions and require immediate attention.
To troubleshoot the cause of your foundation cracks, positively identify the type of cracks you have, and know what steps you can take to combat them further, keep reading.
Primary Causes of Foundation Cracks
Not every crack is serious, but every crack exists for a reason and indicates something about the foundation and, by extension, the structure itself. There are certainly unusual causes for a foundation issue, but these are the most common reasons you may be finding cracks.
Elastic Soil Leads to Settlement
Perhaps the most common cause of foundation cracks, elastic soil causes almost all of the issues most people refer to as settlement. Hearing creaking sounds can be attributed to the house settling. A house does so because of the soil.
A house exerts a huge amount of pressure on the ground on which it has been built. Rain comes, hot and cold temperatures expand and contract soil and rocks under the home, and different types of soil can coexist under the house, which can cause differential settlement. Differential settlement happens when different parts of the home settle into the ground at different rates.
Different types of soil present various issues as well. For example, clay soil can shrink dramatically in drought conditions, causing more drastic settling of the foundation and home, and creating more extensive problems.
The most common cracks related to elastic soil are generally not causes for alarm, which is reassuring, as there isn’t much to be done about this kind of settling.
Homebuyer’s School offers a solid, 10-minute YouTube video with more details about settling here:
Poor Drainage Can Cause Oversaturated Soil
No matter the amount of rain in your area, drainage is an essential part of your foundation’s integrity. If there is poor drainage — even a plumbing leak — water can build up around your foundation and cause serious damage.
Remember that water is the only known universal solvent. Given enough time, water can ruin anything. Let it stand too long against your foundation, and you will inevitably have problems that will need — and possibly expensive — attention.
Tree Roots Impact The Ground’s Moisture
While most people assume that a tree’s root system would push up on a foundation, the opposite is actually true in terms of how tree roots can cause damage. Transpiration draws water from the soil, and this drying of the soil causes it to compact somewhat, resulting in the downward settlement of the foundation.
The presence of a tree near your home does not automatically mean that foundation problems will result, but a homeowner with a tree close to the foundation needs to know how that organism is affecting their home.
Foundations Lose Durability With Age
As your foundation ages, it will become more and more prone to cracks and other issues. There may also be issues related not just to age but when your foundation was created. A foundation built in the 1920s is older and may also lack rebar or consist of a material that is considered substandard today.
While your foundation’s age is not something you can fix without razing the place and starting over, knowing that this is the cause will guide your decisions as to how to proceed with any repairs required.
Identifying the Common Types of Foundation Cracks
While any brittle material can crack, the way it does so can partially dictate the action needing to be taken. Finding a crack in your foundation is one thing. Determining the kind of crack it is will be the difference between panicking in the face of expensive repairs or calmly monitoring something that may not be all that serious.
An inward bowing of the wall may even accompany these cracks in the same spot on both the interior and exterior surface is an indicator of a serious issue. Another item to consider is the width of the crack. Generally speaking, the wider the crack, the bigger the problem you have on your hands.
By far the most serious crack, the stairstep crack appears in the brickwork of your foundation or the exterior walls of your home. Aptly named, this crack follows the mortar between the bricks and makes a stairway up or down the wall.
When found in a basement, these cracks often indicate hydrostatic pressure as saturated soil pushes in on the wall. These cracks may even be accompanied by an inward bowing of the wall.
These cracks may also be caused by differential settlement, as mentioned above.
While it’s possible that stairstep cracks in the exterior brick wall of your home may be resultant from hot-and-cold expansion, this is not a chance a homeowner should be willing to take. Any stairstep crack should be cause for alarm and should be attended to sooner rather than later.
Not as dire as stair-step cracks, horizontal cracks are, nonetheless, serious concerns to note. Pinpointing a single cause of this type of crack is difficult because the location of a horizontal crack is a large part of diagnosing its cause. For instance, cracks toward the basement ceiling may be related to frost issues because the ground near the bottom of the basement does not freeze nearly as often as the ground just a few inches below the surface.
Cracks found above a door or a window may indicate expansion and contraction of materials and are unrelated to your foundation – certainly something to monitor, but not a foundation issue requiring urgent attention.
The least serious of the three types of cracks listed, the vertical crack presents few problems other than the possibility of letting in water, which could obviously lead to more serious issues. However, these are generally related to concrete shrinkage, which will always happen and is not a cause for alarm.
Like any crack, a vertical crack needs to be noted and inspected from time to time, as a vertical crack that grows wider is likely an indicator of a bigger issue. An easy-to-use crack monitor, such as the CRACKMON 4020A Heavy-Duty Building Foundation Crack Monitor, offers convenience as it mounts over the crack and allows for accurate tracking of its size and width.
Other Indicators of Foundation Issues
If you have a basement or a crawl space, finding foundation cracks is very simple. Even without a basement or crawl space, there are signs a homeowner can look for that indicate a foundation crack or other issue that needs attention. By no means a definitive list, below are more common indicators of an issue:
- Cracks at the corners of your doors and windows or near your ceiling
- Windows begin sticking
- Doors no longer latch or begin swinging open or closed
- Cracked or loosened floor tiles
- A chimney begins to lean, whether toward or away from the house
To ensure the longevity of your home’s foundation, it’s important to conduct regular checks and monitor its condition.
- Look for cracks in walls, over doors in the ceiling that weren’t there the last time you looked.
- Pay attention to the ground outside. Are the puddles forming in places where water didn’t use to stand?
- Are your floors sagging or bulging? If your kid’s Hot Wheels didn’t use to move on their own, but now one place in the dining room can be used as a drag racing strip, you may have an issue.
A cursory web search or local contractor can connect you with a comprehensive list of things to examine in your annual or semi-annual home check-up.
Finding the Right Repair Solution
For significant foundation issues, your best solution is to consult with a professional. If your basement wall is sagging inward, you have stairstep cracks running up and down the length of it, and water is seeping in, you are most likely unqualified to fix the issue with your toolbox and a YouTube video.
That said, minor issues can be handled by the adroit DIY-er. The RadonSeal Concrete Foundation Crack Repair Kit is more than adequate for smaller and less serious cracks, and there are other such kits for different kinds of cracking issues.
The national heroes over at This Old House offer hours and hours of information about all kinds of repairs. Here is a video where Tom gets walked through a foundation crack repair:
Any crack in your walls or your foundation should be noted and attended to immediately. There are harmless cracks, inevitable cracks, and severe cracks, but the fact remains that any foundation crack can indicate serious, expensive problems, meaning you shouldn’t ignore even one of them.
If you locate a crack in your home, inspect it further to determine what kind of crack it is. It could be indicative of a major problem, so the sooner you attend to it, the better.
- Acculevel: DIY Home Inspection Checklist For Your Foundation
- Acculevel: When Should You Worry About Cracks In Your Foundation?
- Accurate Leak and Line: When You Need To Worry About Foundation Cracks
- BuyersAsk.com: Foundation Cracks: Causes, Seriousness and When To Worry
- BuyersAsk.com: Tree Roots Crack & Damage Foundations: Transpiration Is The Major Cause
- Complete Basement Systems: Foundation Cracks – The Good, the Bad, and the Ugly
- Inspectapedia: Foundation Wall & Floor Crack Dictionary: How to Evaluate and Diagnose Foundation Cracks
- Inspectapedia: Types of foundation damage organized by foundation materials
- Royal Work: Homeowner’s Guide To Foundation Cracks And When To Start Worrying
- Thrasher: Foundation Cracks: When to Worry
- True Value: How to Repair Foundation Cracks
- United Structural Systems: Complete Guide to Foundation Cracks
- Wikipedia: Transpiration
- YouTube: House settling vs foundation problems: What’s normal and when to worry
- YouTube: How To Fix a Concrete Foundation Crack
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