Adam Tracy, aka The CrackDaddy, aka The Engineer on staff, is here with us to share some more of his engineering wisdom with us. In this episode, Adam explains why foundations bow inward and what can be done about it?
Narrator: The topic of today’s podcast: What can be done about block foundations that bow inwards? Adam Tracy a.k.a. The CrackDaddy a.k.a. The Engineer on staff, is here with us today to share some more of his wonderful engineering wisdom. So, Adam, I understand you’re getting some calls about foundations that are bowing inward. What causes that and what can be done about it?
Adam: Yeah this is a unique situation that really primarily affects block foundation construction. So, when we talk about block foundation, we’re talking about cinder blocks, something that you might be familiar with going to the local big box hardware store, they’re usually scattered about there. So, these cinder block foundations, they’re usually constructed anytime after the 30s and it’s a relatively inexpensive material to construct the foundation. And they’re stacked one on top of each other in a staggered pattern, just like you would lay bricks, and mortared together. And most times they’re not filled, so they’re empty hollow blocks, and sometimes they are filled, but the vast majority of them in residential construction are hollow.
So, the challenge with a hollow construction wall that is held together by mortar is that they’re susceptible to a sideways push in or out of the foundation, and they’re also susceptible to leaning. A concrete foundation is a little bit stronger and it has less chance of, kind of, buckling under a sideways push. But because you have, basically, all these blocks that are staggered together and held together by a mortar, they do have the tendency to fail during a sideways push. So, what can cause this? Well in New England, we have a lot of varying soils and a lot of varying soil types.
On the Cape Cod area, the soil is very sandy, and a lot of the issues that we see in Cape Cod with block construction is due to the soil issue, not bearing a very strong soil so it is susceptible to that. A lot of times what we’ll see is during the wintertime, freezing and thawing and heating of the soil can cause outward pressure to push the foundations inward. Another area that can cause the foundations to go inward is having a large root structure, whether it’s plantings right next to the foundation or maybe it’s that big old oak tree that’s out in the front yard with a huge root system, and it tends to push on the walls. So what can we do about that?
Well, we can’t change the soil conditions, generally, and that would take a very big effort of digging out and replacing that. So, what can we do to a foundation to actually help resist this movement or improve the ability to hold the house up? When we start to see these foundations pushing inward, there’s kind of a point of no return, when it starts to go too far inward, you lose the ability for the house to stay stable above, and in those cases, you might have to replace the foundation. But prior to that, the telltale signs that we see are step cracking in block foundations where the crack will go down one over one, down one over one, almost like a staircase, or you’ll see a large horizontal crack that runs left to right across the wall, these are the early signs that you’ve lost the strength in that wall to resist the push of the soil from the outside. So is that it? We just throw our hands up and say, well, we got to move because we can’t deal with this now? No, we can still save these pretty easily before it gets too bad and before it gets to that replacement category.
There’s a process that we can use to evaluate how much bowing has occurred and whether or not we could keep it from bowing further. So providing that we can evaluate that and it’s still within the realm of being safe, which is the vast majority of them, what we use is a structural carbon fiber technology, and this structural carbon fiber was originally developed for commercial use and used in concrete overpasses, on highways, and what their uses there is it strengthens the concrete against heavy loads of trucks and even rail systems so that it doesn’t buckle and chunk out pieces of concrete down below to the roadways and any sort of passenger cars that might be underneath.
So these are extremely strong pieces of carbon fiber that can get attached to the foundation wall and add in a tremendous amount of strength to the block foundation. Every strap that we put on is the equivalent of bolting on a half inch stick steel plate that’s 12 inches wide from the top to the bottom. So if you’ll kind of put that in your mind of how strong that would be to resist any sort of movement inside, it’s almost like strapping on an I-beam every 4-5 feet across to the foundation. That’s a relatively non-invasive process, it can be done in, usually, less than a day for a wall, and then the beautiful thing about it is that you can paint right over it and you won’t even see that they’re there. So these old foundations or these block foundations can be easily maintained, if you start to see these horizontal or step cracking, then we have a process that’s non-invasive and can maintain that integrity of the wall for a long time.
Narrator: Great information, Adam. It’s good to know that this can be done without spending tens of thousands of dollars on a new foundation.
Narrator: If you have a basement water problem and think you need a professional, or, if you’d like more information on foundation crack repair and basement waterproofing topics, please visit A1FoundationCrackRepair.com or call Rich at (866) 929-3171. Or you can email Rich at firstname.lastname@example.org. Thanks for listening and keep that basement dry.