Maeve S. from Fridley asks:
I recently saw an article in the Pioneer Press about foundations being affected by our recent drought conditions. Why does this happen and what can I do about it?
Bruce LaMere says:
Good question Maeve, we’ve recently seen an uptick in questions and requests for estimates regarding foundation repair. First we should start on how a home’s foundation is built. When a house foundation is built, it is built on a concrete footing that displaces the weight of the home onto a large area of soil. The concrete footings are installed below the frost level of a given region (see our Frost Heave or Footings article for more information), to aid in the stability of the foundation. This way frost can’t affect your home, and is why most homes in Minnesota have basements.
Taking frost out of the equation, the other major issue that can move a foundation is if the soil sitting underneath the concrete footing shifts. What can make this soil move? One issue is the expansion and contraction of soil caused by water. As soil soaks up water, it expands, and as it expels water, it contracts. This type of action is worse in wet soil such as clay, and is usually not a problem in a sandy soil. In normal conditions the moisture content of soil is relatively stable and is counteracted by the engineering of the foundation and footings. In severe drought conditions, such as what we’ve been experiencing, the soil can lose so much water content that it shrinks beyond normal parameters, and causes a home’s foundation to shift. This shifting is what causes cracks in a foundation wall.
There are some preventative measures that can be taken to avoid this problem. In severe droughts it can be advisable to water your foundation. One good way of doing this is to run a soaker hose around your home’s foundation and let it run for a couple of hours each week. This can return an appropriate amount of moisture to the soil surrounding your foundation and keep it from shrinking too much. Another option is to install a root barrier around your house to keep tree roots from soaking up moisture from the soil around your foundation. This is especially applicable if a home has a significant amount of tree growth around it. If these preventative measures aren’t enough, foundation repair may be necessary.