Russel Ray is a very professional, knowledgeable and experienced home inspector from San Diego CA and fellow Active Rain blogger. Over the last while, he has written a series of posts on the subject of cracks in a property. If you have a crack and are unsure of the impact on your property, consult with a professional, such as a structural engineer, however, as a primer, and to gain general knowledge, I have found Russel's information very helpful. This is Part Four of Russel's series and discusses some very distinctive cracking in a foundation, in the shape of a "V","W","X", or "Y" either right side up or inverted... these can be problematic and a structural engineer might need to be consulted...
Here a crack, there a crack....
DISCLAIMER: This discussion is based on several decades of experience in real estate, including as a home inspector and general contractor. I am not now a concrete professional or licensed structural engineer, so if you are not comfortable with common concrete cracks and our discussion here, hire one of those two professionals to help you. This discussion, however, should help you be a little more knowledgeable about cracks so that you don't just automatically assume the worst. Cracks happen, kind of like ActiveRain blogs.
I'll presume that you have read previous lessons.
So far, we've discussed
- curing and shrinkage cracks in the foundation stem wall in the garage, and
- cracks in the garage floor.
Let's move to the foundation of the house proper and the interior living area. Cracks in the foundation here can be much more problematic because of what we have going on inside. Certainly no one wants to sit it a sloping living room, or have to put a brick under one side of the entertainment center in order to level it, or to have dozens of ugly cracks in the walls and ceilings.
If you see a crack like we saw in Lesson One that initiated this discussion, it's probably one that can also simply be repaired with epoxy. However, before making that determination, go to the inside of the house where that crack is and look at the ceiling, wall, and floor there. If there are cracks in that area, it's probably best to have that area of the house looked at by a qualified foundation professional or structural engineer.
There are exceptions, depending on the type of foundation (crawl space, basement, or
slab-on-grade), the type of wall (drywall or lathe-and-plaster), and the type of crack (length, width, and whether it's a diagonal, straight, stair-stepped, etc.). We'll discuss all of those in a future lesson, but as you can see, it takes a lot of knowledge and experience working with concrete to put 2, 7, 5, and 7 together to get 20. Being off just one number can make a significant difference.
Following are some pictures of some cracks in slab-on-grade foundations that can indicate more serious problems.
Figure 1 shows a Y crack.
Almost any V, W, X, or Y crack, either right side up or upside down, indicates some severe stresses in the area. That's because stresses tend to move in the line of least resistance (the weakest link, so to speak), so to have two lines of least resistance right next to, and intersecting, each other indicates something serious going on. What happened was that stresses caused the first crack, but that crack didn't alleviate the stresses. In fact, kind of like an earthquake, it might have caused stresses in other areas, which then resulted in the second crack, forming a Y.
Sometimes it's simple to determine the cause, such as damage to the foundation there by the highway engineer testing his new jackhammer on the other side of that wall (this was a garage foundation). Other times it requires an engineering professional to try to track down the cause.
Figure 2 shows an exposed foundation footing, which is rarely good. Every time that I have found an exposed footing, usually due to erosion, I have found cracks. They seem to go together.
When the foundation footing and the stem wall are cracked, I'm pretty sure that I'll find a cracked slab inside the house, and that's exactly what we found at this house. Fortunately, the interior floor covering was carpet, and the sellers were only too happy to cooperate with the buyers in their due diligence by letting us pull up the carpet.
We caught this problem in time because there was no damage to the interior foundation, so some epoxy, added soil to cover and support the footing, and some gutters and downspouts on the roof (sadly lacking on San Diego homes due to our measly 10 inches of rain a year) to prevent erosion should abate any future problems here.
"Cracked slab" seems to be a dirty word in real estate, but many cracked slabs also involve simple curing and shrinkage cracks. What one has to be aware of is expansive soils, lack of a vapor barrier between the concrete and the earth (difficult to tell unless you saw the house being built), and where the through-slab plumbing is located.
Any hole through the slab creates a weak point, so if the weak point is contributing to the cracks in the concrete, a professional engineer might be required to determine abatement options. Sometimes the water and sewer pipes will have to be rerouted in order to repair the slab.
Figure 3 shows a fairly straight horizontal crack. This type of crack is usually what we call a "cold pour" crack, and they usually occur in corners, such as this little corner, and other areas of the foundation that are difficult to work in, such as bathrooms.
A cold pour usually means that:
- the union bell sounded Friday at 3:00 p.m. and everyone took off to celebrate the weekend without finishing the job
- the first concrete truck ran out of concrete and the next one wasn't due until the next day
- the South-of-the-Border workers just got paid and had to head South to celebrate.
In other words, it happens when concrete is poured but more is needed and not available until several hours — sometimes days! — later. Newly poured concrete will not adhere very well to partially cured concrete , and this is the type of crack that results.
Cold pour cracks usually are not of a structural concern as long as you keep water away from the foundation — note that irrigation sprinkler head right there, which is why I took that picture to help explain to my Clients not to water there — so that the soil doesn't turn to Jello or erode. Jello is great to eat but it doesn't support much of anything.
Figure 4 shows what can happen to a cold pour crack if the soil is waterlogged. You can see the wet soil there and how the crack has opened up.
This now becomes much more serious because there's little to support the interior floors. At this house, the floor on this side of the room had a serious slope in it, a slope that I could feel just by walking the floor. Didn't even need a manometer survey here.
As always, if you are not comfortable discussing common concrete cracks, hire a professional to help you.
Join us soon for Lesson Five.
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