At least in a manner of speaking. Everywhere we go we look for cracks in foundations. When we find them we try to classify them and evaluate the surrounding influences that might make the consequences better or worse. Cracks are a foundation’s way of relieving stress. The majority of houses offer one or more cracks for examination. So don’t panic at the sight of the first one. Let me offer a layman’s primer to the types of foundation cracks that may be encountered.
There are obviously ‘bad’ cracks that we refer to as ‘structural’. In inspector language, we might write, “the structural integrity of the foundation wall has been compromised”. What we mean is that the foundation wall is not doing its job of holding up the house properly. The damage is potentially significant and the cost of repair usually is too. The other thing to remember about a structural defect is that we are saying that the damage is going to get worse if you don’t get things corrected. If the foundation is not holding up the house in its original position, the weight of the house above will cause further stress cracks and movement. Don’t lose hope. Just because a crack is significant doesn’t mean that it can’t be properly repaired.
Inspectors look at the size of the crack, its orientation and for any displacement. The wider the gap the worse the crack. If you can get your fingertip in a crack, there has already been significant movement. A horizontal crack is generally of more concern that a vertical one because it suggests displacement. Displacement is when one side of a crack has shifted out of alignment with the other; the two sides are no longer in the same plane. Pressure from the fill around a foundation sometimes causes the wall to start to bulge inwards. Most commonly this happens with block foundations.
The picture shows a block wall that has started to buckle inwards. It has what we refer to as ‘step cracking’ as the mortar has opened between the blocks. The bulge displaces the blocks out of their vertical alignment and is often detectable by eye when sighted along the wall. Left unchecked further movement will cause the wall to collapse and the home will be unsupported along this section of wall.
The least expansive cracks are referred to as ‘hairline’ cracks. You can see them but the sides are still in contact and aligned. They are often located around basement window openings. Some cracks are caused by the tension in concrete drying out as it ages. Minor settlement can cause these too. If a crack has remained unchanged for years there’s less risk of future movement as settlement usually diminishes over time. The uncertainty is whether a recent crack will widen into something more serious. The pictures we put in our inspection reports can be a reference to refer to later. Wider cracks need special devices to help track millimeter size movements over time.
Cracks that we find in basement and garage floors are the least worrisome. It’s hard to find a house without them and unless the floor is buckling, or contains in-floor heating, inspectors aren’t going to get too worked up about them. In traditional house construction the floor slabs have very little structural significance. They are poured after the house is built and and the roof is on. They don’t play much of a role in holding the house up.
A non-structural crack that occurs in a well-drained, dry environment is pretty harmless. Once past the issue of structural support, the enemy we watch for is potential water intrusion. Concrete is not waterproof and the presence of cracks add to the potential to leak. Past leaks often leave signs and we will certainly comment if we find those. The influences I referred to earlier are things that either bring more water to the crack or fail to take water away from it. The grade around your foundation wall should slope away from the house. Landscape edging or porous fill like river rock can pool water along the foundation wall. The lack of an eves-trough on a roof surface above that drains towards that edge, or downspouts that empty too close can feed large amounts of water to an otherwise harmless crack.
I hope this article has helped to give you a better understanding of what Home Inspectors as thinking about while they look at a foundation wall. Ideally you now have some insight into distinguishing a serious crack from a lesser one.
Photos courtesy of AboveWater Foundation Waterproofing & Restoration Services Inc.
Author: Rob Cornish is a Home Inspector in Ottawa, Canada. © 2013 HomeXam Inc.
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