Here’s the big question that people want to know.

When people see cracks in their walls and floors, and doors and windows out of square, they get concerned and have a number of questions. Usually, it boils down to: will the house continue to move? And will it get worse?

Unfortunately, by calling foundation repair companies, you will get the opinion of a commissioned salesperson who benefits from your perception that the damage is horrible, will continue, and worsen over time. They tiptoe around and covertly infer structural instability without ever saying it outright.

Which Engineers Can Help

Many people instinctively reach out to structural engineers. After all, the structure is deteriorating and appears unstable. However, in 30 years, I have rarely seen soil-caused foundation movement severe enough to be structurally unsafe. Most structural engineers will issue a letter that says the structure is not structurally deficient.

When pressed on whether it will reach a structural deficiency, they will say that if the soil forces continue, it is possible. When pressed further on whether soil movement is continuing, the answer will inevitably be that a geotechnical engineer is required to determine that.

Assumptions Made By Foundation Repair Salespeople

Most foundation repair salespeople will argue that if the soil has shifted in the past, it will likely continue to do so. This is oversimplistic. I remember thinking those thoughts early in my career. Let’s look at this in more detail.

First, realize that soil is super complicated.

See my blog post on this…Moisture may be moving slowly underground, unseen. Or it may have stopped… unseen. Remember, some soils consolidate, others expand and contract, and some layers may offset each other.

Second, the time since the last measurable movement is really important. Almost all structures settle initially during or shortly after construction. Most geotechs estimate that a typical house will settle ½”–1” initially. It is why you see roof tiles stacked in small piles on houses for a long time. As soon as the framing is complete, the tiles go on while plumbing, electrical, insulation, and drywall work are underway. During this time, most of the settlement occurs before the drywall is taped and textured in order to minimize cracking. 

If the damage is caused by consolidation, it will improve over time. And if that time was many years ago, continued movement is unlikely. If the movement is from expansive soils, the cyclical movement could continue, depending on underground moisture conditions. Much of that water comes from the surface immediately above it. If that water is properly controlled, continued movement will be minimized.

This is why, in the homeowner’s interview, asking about the timing of the damages is so important. See the blog here for a list of interview questions.

Additionally, it is better to examine movement over time to document ongoing movement.

Foundation repair salesmen who want to keep their jobs and earn commissions will not likely agree to monitor that home over 6–12 months. Additionally, they will likely not agree to recommend grading and drainage only, then monitor performance to determine whether the ongoing movement remains within acceptable limits.

Only Trained Forensic Geotechs Can Opine on the Probability of Future Movement

The plan of investigation and monitoring should be the responsibility of a forensic geotechnical engineer. They understand the local soils. They understand how the local geology formed and evolved over the past few hundred thousand years. They perform borings regularly and characterize the soils in the layering of those borings. They recognize the risks of future movement and the best design programs to understand a site’s soils and moisture.

Ramifications

In the end, what people really want to know is the probability of continued movement. Can we just fix it cosmetically and be done? Is minor continued movement acceptable?

Geotechs, especially forensic geotechs, are really the only ones who can answer this question honestly and with the expertise required. Don’t buy into the opinions of anyone else, especially if they have anything to gain from their opinions.

If you are selling your house, you may not have the luxury of documenting performance over 6–12 months. If, on the other hand, you proactively seek out a professional ahead of time, you may be able to save that $70,000 if you can document that it is inside of the allowables that engineers use to characterize movement, or even if it is not, that it is done moving and may be documented as such.