Your concrete slab is . . . well . . . kinda ugly in places. You’ve got some unattractive flaws in your concrete slab foundation and are wondering if this means your home has or will develop foundation problems.
You’re not alone in this concern. Many homeowners often confuse certain concrete flaws with foundation problems and we’re here to put your mind at ease.
At Anchor Foundation Repair, we’ve been assessing and repairing slab foundations for 35+ years. We know what signs you might see around your home are stability issues, and which are more cosmetic in nature. We are happy to fill you in on these common visual concrete issues so you can stop worrying.
This article shows examples and explains the causes of typical cosmetic concrete issues people frequently think affect their home’s stability but don’t. By the end of this article, you will understand what concrete signs don’t (and a few that do) signal a foundation problem for your home.
Top 6 Confusing Concrete Foundation Flaws
These concrete issues often cause homeowners distress and worry. We get calls asking about these kinds of signs all the time and can certainly understand why they confuse homeowners into thinking they have foundation issues.
These visual concrete flaws are not *attractive* or they attract all the wrong kind of attention and make people wonder what’s up with your slab.
These concrete situations are not inherently structural issues. Your slab may not be flawlessly beautiful, but it’s generally structurally sound even with some of this cosmetic stuff going on. Listed from most to least common:
- Hairline cracks in top surface
- Corner Pop
- Spalling
- Rebar Exposure
- Honeycombing
- Flaking
In the vast majority of cases, these concrete flaws are either *kinda normal*, workmanship-related, or a “conditions at pouring time” kind of thing. You might even see more than one flaw in the same slab (as you will see in the upcoming photo examples), especially due to workmanship issues. We’ll be more specific about what causes each issue when we talk about each one individually.
*Disclaimer Alert* Now, just because we’re saying that your slab is structurally sound even with these issues present, that doesn’t mean we don’t see these issues on homes that also happen to have foundation problems.
The key is that if you see just these issues on their own then it’s unlikely a structural problem. These visual cues are not positive indicators of foundation settlement. But some homes might coincidentally have these flaws in conjunction with the true signs of foundation problems.
1. Hairline Cracks in Top Concrete Surface
This happens all. the. time. Someone takes up their carpet and they see hairline cracks in concrete floors and they worry that it is a foundation problem. These cracks have no gap or level difference between sides but are just fine, hairline cracks running throughout your bare slab.
People don’t know it’s there under the flooring or carpet until it is exposed. But you might see these kinds of cracks on a garage floor where concrete is exposed.
Hairline cracks are a normal part of drying concrete and are present in even the most optimally-poured concrete slabs. You don’t know it’s even there until you take up the carpet, and they do not indicate movement or settlement of your foundation.
A good rule of thumb here is that if you didn’t think you had a foundation problem before you picked up the carpet, then don’t think you have a foundation problem after you pick it up and see a few cracks either.
2. Corner Pop
Corner pop *looks bad* and makes people worry, but it’s not always a big deal for your foundation. Corner pop occurs most often on slab foundation homes with brick or masonry walls.
This concrete flaw literally looks like the corner of your foundation near the ground has “popped” off the house. Or the corner could just be cracked but looks like if you were to hit it really hard with a sledgehammer that the corner would break off.
What happens is that there is supposed to be a barrier between the concrete slab and the brick wall. When the barrier is non-existent or flawed, it causes contact between the brick wall and the concrete. These two materials expand at different rates and when the brick expands more it can pull/push the corner of the slab off.
Sometimes corner pop is a concern and sign of foundation issues and sometimes it is not. Corner pop can be part of a larger foundation problem (brick or non-brick) OR is more commonly caused by opposing expansion forces of masonry and concrete in a brick home which does not indicate a foundation issue on its own.
If the only sign you are seeing in your home is corner pop, and you have no other signs of foundation problems, then this is more likely to be a workmanship issue where the barrier between the materials is not fully in place or there at all.
3. Spalling
Spalling is a concrete flaw that results in concrete with a crumbling or chipped-off appearance with smaller pieces breaking off from the slab. It can also look like pitted-out pockmarks on the surface. Sometimes spalling deterioration will result in rebar exposure as the concrete will chip off until the first line of steel reinforcement is revealed.
Spalling is a problem caused by excess water either during construction or intrusion at other times in the concrete’s lifetime. More specifically:
- Too much water in the concrete mix
- Rust buildup due to moisture on rebar that creates pressure from inside the concrete
- Freeze and thaw cycles where water/ice inside the concrete expands and contracts
Poor workmanship with the concrete mix or improper rebar placement can also result in spalling. For example:
- Low-quality concrete mix
- Concrete that does not adequately cover the steel reinforcement
- Timing issues between layers of the concrete pour resulting in poor inter-layer bonds
Spalling is a surface problem but does not reach far enough into a concrete slab foundation to compromise structural integrity. Internet sources indicate that if the spall intrudes less than ⅓ of the way into the surface, then only cosmetic repairs are needed.
So when you think about a slab foundation being the width of your whole house, spalling barely *scratches the surface* of your slab – usually only making its way to the first layer of rebar. Now, no one said it was pretty or that you wouldn’t want to do something about how it looks, just that it’s not a very likely sign of foundation issues.
4. Rebar Exposure
Steel rebar exposure is closely related to spalling as explained in the section above, so it probably could be a sub-section of spalling. But since rebar could get exposed for other reasons I decided to keep it separate. Also, not all spalling has rebar exposure, and not all rebar exposure is caused by spalling.
But like spalling, rebar exposure is a workmanship issue. Rebar needs to be placed away from the exposed surfaces. If it’s placed too close to the side edges or the top of your slab, spalling can occur simply because it’s not embedded deep enough or the joint placement is incorrect.
Rebar exposure could even happen if something hits the side of your house hard enough and a piece chips off due to the rebar being too close to the edge.
Since we know there’s way more rebar in your slab than the outermost pieces, even rebar exposure isn’t going to compromise the structural integrity of your entire foundation. A few crumbles of concrete on the side of your home aren’t going to make your walls fall down.
5. Honeycombing
Honeycombing is (in my opinion) the most unattractive concrete flaw. It gets its name from a similar appearance to the honeycomb structure bees make in their hives.
*Personal Note* For some reason, insect structures really gross me out. So I know it’s honeycombing if it makes my skin crawl when I look at it.
Honeycombing is 100% a workmanship issue caused by one or more factors. Here are a few examples and this other article has a massive list that all point to *someone didn’t do something right*:
- Inappropriate mix of aggregates – too coarse, not enough fine material
- Lack of concrete workability – i.e. too stiff
- Insufficient vibration and excess air bubbles
- Pouring the concrete from too high a height
Luckily for everyone, honeycombing is not too terribly common at least in our area which is perhaps a testament to our Brazos Valley homebuilder quality.
Honeycombing can affect the overall durability of concrete (meaning it might not last as long as a perfectly done slab), but from a structural standpoint, your slab foundation will still be able to do its basic job. For this reason, we say that honeycombing is typically cosmetic and not an automatic reason to worry about foundation problems.
6. Concrete Flaking
Also called scaling, concrete flaking is when the surface flakes off in very thin layers. It looks like your concrete has a serious case of dandruff. Flaking most often is caused by too much water in the concrete mix.
Another common reason for scaling and flaking has to do with freeze-thaw cycles (which we don’t have here in Central Texas) or from using salt on your flat concrete surfaces to prevent ice accumulation (also not common here). Flaking most often presents itself on horizontal surfaces like sidewalks and driveways for this reason.
Concrete flaking is something we don’t see often with foundations, which is why we have it listed last and the least common. But again, it’s a cosmetic surface problem, and it’s unlikely that you have a structural foundation issue.
A Reminder of the Purpose of a Home Foundation
After going over all of these cosmetic concrete flaws, I feel like I should offer a refresher on the true purpose of all types of home foundations.
All foundations have a few basic purposes for you:
- To support the structure of your home
- To keep groundwater away from you and the rest of your stuff
- To serve as a vapor barrier to both the water and soil under your home.
These are all good things that keep your home solid, stable, and dry.
Even if you have a cosmetic concrete flaw, your home’s structure is still well-supported and can easily carry the weight of the rest of your home. A concrete flaw like the ones we have discussed here is not going to allow groundwater to start coming into your home or getting your belongings wet. Your vapor barrier is still intact even when these concrete flaws are present.
SO, your foundation can still do its basic job even with these cosmetic concrete issues.
The True Signs of Foundation Problems Are Not In the Concrete
Now you know that these common concrete flaws are not going to automatically result in foundation issues. Foundation problems are caused by foundation settlement. Foundation settlement is most often caused by expansive clay soils and not because of a concrete imperfection.
The true signs of foundation problems do not typically reveal themselves in your concrete. The most reliable way to identify foundation settlement in your home is by looking at the visual signs in your home’s finishes like drywall, doors, trim work, and brick veneer.
At Anchor Foundation Repair, we’ve been helping Brazos Valley homeowners handle their foundation repairs with confidence since 1985. So many companies out there try to freak you out with dire warnings about your concrete flaws (or some other issue), urging you to *buy their thing now* because it’s the *best*, it’s hard to know who is shootin’ straight with you and who just wants you to take your money.
We don’t prey on your fear of foundation issues by trying to sell you something you don’t need.
Instead, we offer impartial guidance and education so that you can take part in assessing your home and be 100% on board with any repair decisions. Check out the Ultimate Picture Guide to Foundation Problems (Real + Misleading Signs) for more detail on the true signs of issues.