Q. Several weeks after Hurricane Sandy, I noticed a small sinkhole next to my blacktop driveway. The hole goes under the driveway, and part of the driveway is sinking. I also noticed that cracks in my cement garage floor have gotten longer and wider. My gardener also filled in a sinkhole next to my house. My plumber discovered another sinkhole in the garage. He said it probably extended under the garage, and that I should replace my driveway. I read your column about replacing soil with expanding closed-cell foam. How can I find out if this would be appropriate for my situation? What companies do this job? Should an engineer inspect my property? I don’t have flood insurance, and my homeowner’s policy doesn’t pay for anything flood-related. Is there a less expensive solution?
A. Yes. In a word, move. Move every six months and you can avoid the expenses of property ownership. Or live in a vehicle. The insurance companies were very quick and very helpful in writing checks for vehicles.
I’ve been commenting on the next problem, sinkholes, for several months now, and have been inspecting and remedying structural problems caused by the dynamics of losing soil under homes and paving, such as your driveway. Whether you hire an engineer isn’t the problem. The kind of work they do is the problem. Structural or civil engineers and architects who design solutions for drainage and soil conditions are the qualified individuals you should seek. I never understand why people ask only about engineers, and not also about architects. Architects are also trained, licensed and qualified for this type of remediation.
As for expanding foam, it may not be a good solution for you. Under a building, the foam insulates, fills holes, adheres to the building materials and remains buoyant. Under a driveway, it may lift the paving when flooding occurs. Instead, the area of the hole must be examined, including digging around it or doing soil boring, depending on how critical the location is to other built forms. For example, a driveway may not need soil boring, since its ability to support cars is less critical than the requirements for a whole building.