Here a Crack, There a Crack
March 21, 2022
Here a Crack, There a Crack
March 21, 2022


You’re watching an action movie and there’s a scene where a crack appears in the ground, or road, or floor. The soundtrack is ominous and loud, the ground is rumbling, the crack grows and grows, things start sliding toward it, furniture or farm animals or cars are disappearing.  Oh, and the hero saves a little boy and a puppy from certain death at the last possible second.  You get the idea.  Cracks are terrifying, right?  Well, no, not in real life, at least.

After working with more than a thousand clients and hundreds of agents, I can say with confidence that a crack in a foundation is the one thing that concerns people more often than anything else. That is certainly understandable, but it’s really not nearly as scary as it might seem at first. Let’s dive in a bit to get an understanding of foundation cracks and what might be found during your home inspection.

Water is wet, concrete cracks!

I have a lot of sayings in home inspection, and that’s one of my favorites.  It’s a Ken Ray Original (C) (TM), Copyright, Trademark, but feel free to use it at parties. :) 

Put another way, I’m surprised when I see a foundation that is not cracked to some extent.  It’s pretty much a guarantee that a concrete wall or floor will eventually crack, usually from shrinkage during the curing process (more on that below).  It’s worth noting that cracks can appear in many different materials, not just poured concrete, including stone, concrete block (aka CMU), or brick. In finished spaces it can be found in plaster and drywall as well.

The nature of the crack is vital – the size of the gap, the direction, the length, the location, and the quantity. All those characteristics are clues about the severity of the situation and what should be done about it. Common causes of cracks include:

Normal shrinking during curing.  The material contracts as water evaporates, leaving ‘hairline’ or ‘shrinkage’ cracks. These are sometimes hard to spot, but (per the quote above) they are quite common.  

Poor drainage outside.  Every Kensa inspection puts a big focus on water, and poor drainage leads to erosion, which leads to…

Soil settlement.  Gravity is inescapable (at least for a foundation). As the ground erodes or compacts and shifts, crack scan appear and grow slowly over time as the foundation moves a tiny bit at a time into the eroded or compacted area.

Static pressure.  This can manifest as a horizontal crack, sometimes with displacement or bowing inward, such that the flat surfaces on either side no longer aligned. That is usually a more serious scenario than most other crack types.

There are other possible causes, of course, but that gives you an idea of the variety of factors.  There can be other symptoms related to the cracking that go beyond the foundation, such as cracks in drywall or brick siding, and sometimes doors and windows will have uneven gaps around them, or they stick or rub when used.  All these signs are carefully considered when recommending a course of action as part of your inspection report.

Side Effects

Foundation cracks should be repaired to help avoid several other problems.  Cracks can create a path for water seep to in, radon gas to rise, and make it easier for insects like subterranean termites to stroll in. Those are the main reasons to have cracks repaired. It’s very rarely a structural issue.

So, now that we have some basic background, let’s look at some actual cracks seen on actual homes and documented in actual inspection reports for actual clients:

This foundation wall crack is an example of the most boring settling/shrinkage crack in the whole entire world.  The size, shape and direction, along with the lack of any visible water penetration, all add up to something to note as being present but nothing more.
As seen on a slab. I call this one the Reverse Triangle Crack, or Triple Crack.  It’s a common pattern, and may indicate a slight high spot where the three cracks meet. Like the foundation wall crack above, it’s common and worth noting that it's present, but by itself does not indicate a structural problem.
Here’s one that was big enough to warrant more attention than usual.  This crack has been repaired, although it's not pretty to look at.  I always say that I’d rather see repairs than damage, and this was noted as such in the report.
A repair was attempted on this crack, but the repair material itself also cracked. That could be a sign of continuing movement, or simply that the repair was done incorrectly.
Speaking of repairs, this crack monitor was installed to show movement over time.  A qualified professional contractor or engineer would determine what, if anything, should be done.
Here’s an older stone foundation with a parge coat. This crack should be monitored, but is also very common.  This foundation has been around longer than both of us put together…context!
A nicely repaired crack, I like it!
An extreme example of water entering through foundation cracks.
Can you connect the dots? The gutter downspout, water stains, the erosion, and the stair-step crack with a large gap... Water is very powerful! See the Kensa Resource Article titled Gutters 101.
Technically this is a wall, not a foundation, but it's a great example of a serious type of crack.  Notice how this crack is wider at the bottom?  Not good. This detached garage was literally on a small cliff (the drop was about 30’), the edge of which is about a foot outside the wall on the right side.  I told my clients it was potentially unsafe and recommended evaluation by a structural engineer. It was a rare scenario.

Repeats Are Okay :)

Just a reminder that foundation cracks like this are not the end of the world.  Again, this type of crack is very common, and can be found on the majority of concrete foundations.  The extreme examples are included just to help you understand the gamut of possibilities. Context!

There are other places for cracking to occur, such as interior walls and ceilings, driveways and patios, retaining walls, and brick siding (aka veneer).  We’ll cover those another time.  Meanwhile, you now have a basic understanding of some of the types of cracking to expect in concrete foundation walls and slabs.

This article is not intended to cover every crack’s cause, cure, or category.  Nor should you rush down to your basement and try to self-diagnose any cracking you might find.  Leave it to the trained professionals :)  At this point you should be much more comfortable with foundation cracks -- they are very common, and it’s not the end of the world.

Calm Clear Context!

Book your home inspection with Kensa to experience it for yourself.