07 Dec Foundation problems and the value of a good structural engineer Or… Help, there are cracks in my foundation!
By Lou Perron
People often ask me about cracks they have discovered in their foundation. Before I go further, I need to make a disclaimer — I am not an engineer. That said, I did study structures and materials as part of my architectural training, and have been involved with many repairs over the years. I’ve learned what to look for – and when I need to bring in an expert.
First of all, what’s a foundation? When you start building a house you dig down below the frost line to undisturbed ground. At this point the soils are compacted so nothing should budge. Then a trough is dug and filled with concrete to create a “footing.” This is a wide continuous base on which the foundation is built.
When you see a crack it’s important to determine where it is and how severe it is. In order to figure out whether it’s a big deal, you need to know what kind of foundation system you have. For this article I’m going to talk about “pier and curtain wall” foundations.
This type of foundation is most common in the pre-1950 houses in Durham’s in-town neighborhoods. These foundations are made with a series of supports or “piers,” which are located at intervals of about 6 to 8 feet along the perimeter of the house and in the corners. Most often the piers are made of a double layer of brick. In addition to the piers at the perimeter, there will also be a series of free standing piers in the center of the house. These piers are usually 16”x16” and are designed to support the floor, wall and roof loads.
In between the piers are one brick thick walls called “curtain walls.” It is not meant to support the house, but is just there to close in the basement or crawlspace, keep it dry and keep out the critters.
With this kind of foundation, the main cause for concern is when there’s a crack in a pier, parts of the pier have moved or if the pier is missing mortar between the bricks. When the piers can’t do their job, the curtain wall may end up doing it, even though it wasn’t designed to do this. This can cause cracking or bowing. This is generally only an issue if there’s a problem with the piers. As long as the piers are secure, then cracks or even bowing in the curtain wall are usually cosmetic. A mason can easily fix this.
The thing to be worried about is a major crack in a pier. Then it’s a good idea to call in an engineer. While many homeowners or buyers feel this is just an additional expense, the cost is small considering that foundation repairs can mount into the thousands and tens of thousands of dollars. An engineer can tell you if the crack you’ve found is a major problem and identify cost-effective solutions.
Why not just call a foundation contractor? While there are some very good foundation contractors, there is an inherent conflict of interest when you ask a contractor to provide you a solution as well as do the work. No matter how honest the contractor, they have a financial interest in recommending an expensive solution, even when there’s a less expensive solution that will solve the problem. When you hire an engineer, they work for you, and have no stake in the cost of repairs.
Also, most contractors are not structural experts. I’ve noticed a tendency toward overkill that sometimes doesn’t even solve the problem. I’ve had an engineer out to look at work that cost thousands of dollars but still didn’t fix the problem. The engineer just shook her head.
So if you notice a crack or sagging, don’t get caught up in foundation hysteria. Take a deep breath. Ask your broker to recommend a licensed structural engineer. Have the engineer look at your foundation and identify any structural problems. If your engineer believes repairs are warranted, ask her to recommend a specific solution, in writing. Then have contractors bid on the work.
Your small investment in the services of an engineer could save you thousands of dollars. It’ll also give you peace of mind and confidence when you sell your home.