Tuesday, May 23rd, 2017 by Niles Erickson
Why Do Foundations Crack?
Foundation cracks form for a variety of reasons and will be noticable as:
In the New Hampshire and Massachusetts areas, the three main types of foundations we generally see are traditional poured concrete, block foundations, and what are called stone, or fieldstone, foundations. Other homes are also built on slabs. No matter what material your homes foundation may be composed of, one of the forms of cracks mentioned above may be visible somewhere within it's walls.
Perhaps the most common cause of cracks in a concrete foundation are formed as the concrete cures. This occurs when there is excess water used in the concrete mix, if the concrete dries too quickly, or if the material or location is not properly prepared. While these types of cracks are common, not all of them are alarming and require immediate attention.
Other times, cracks form when the subgrade soil is not properly compacted, or if material such as trees or roots are buried beneath the foundation. The soil in such cases is vulnerable to sinking, shifting or expanding, which means a lot of pressure is added to the foundation directly, rather than transferred into the earth surrounding the structure.
And lastly, sometimes water is the culprite. High water tables, or flowing water, can remove or shift soils, and so overtime as the soils are displaced, the foundation becomes less stable and cracks as voids are created underneath the footings.
Two Types of Foundation Cracks
No matter what the cause of the foundation crack me be, they can be categorized into two broad categories; static and moving. To put it simply, static means the foundation settled or moved slightly, resulting in a crack, and has since not moved very much (or at all). Or, something bigger, and worse is happening with your foundation. The crack has formed and is gradually growing wider, moving as the structure continues to sink or settle over time. When it comes to a moving crack, the issue at hand is not so much the foundation wall itself, but the soil surrounding it.
*It's worth mentioning here, this article will not discuss how to determine whether the crack is moving or static, or how to repair a foundation which may be settling or sinking. Instead, it will focus on how to properly seal the foundation crack itself.
Do's & Don'ts of Crack Sealing
No matter what has caused the foundation to crack, or whether it is moving or static, the crack should be sealed. Sealing the crack correctly will preserve the integrity of the wall and also prevent water from entering into the space within. In this article, we discuss crack sealing from the inside of the wall, as sometimes sealing from the outside is not an option.
During a number of our foundation inspections throughout New Hampshire and Massachusetts, we often come across a crack which had previously been sealed incorrectly, either by the homeowner or by a hired professional. So what does it mean to be sealed incorrectly?
The common mistakes we encounter are surface fills, such as putting caulking into the crack, or packing the crack with hydraulic cement. Both of these applications are non-permanent solutions to any crack seal job. While sometimes they may look like a job well done, in fact they are making the problem worse.
These are mistakes for 2 main reasons. The first being, over time cement or caulking will either erode or fall away, reopening the crack. The other reason these applications are not effective, is that they don't divert the water away from the wall, but rather end up acting as a dam. With the water being stopped and not allowed to move freely it can potentially cause further damage to the integrity of the wall, slowly eroding it away.
When our service professionals encounter a sealed crack which was done incorrectly, there are a few ways to address the situation.
To properly seal a foundation crack, Erickson Foundation Supportworks uses two different methods, depending on the type of crack and the condition of the wall.
For a polyurethane injection system, we take the following steps:
For a Flexi Span system, we take the following steps: