There is a common saying in the concrete world that there are two types of concrete: Cracked and about to be cracked. This is almost true of homes as well. Depending on where you live, your home may or may not have easily identifiable signs of distress. But are these signs a signal of serious foundation defects or just typical foundation settlement?
Signs of stress or foundation movement damage
These signs of distress typically are:
- Cracks in drywall
- Cracks in floors
- Cracks in exterior walls (masonry, stucco, etc.)
- Sloping floors
- Doors that are pinched (gap at top on one side but not on the other side)
- Windows that are pinched
Some of these are more meaningful than others, and one crack by itself is usually not an indicator of foundation movement, unless it is large (big enough to jam the sharp end of a pencil into it and have it stay in). For example, stucco cracks for many reasons including thermal expansion and contraction and improper lathing of the paper and wire. Floors also crack for many reasons, the most common being plastic shrinkage. Concrete always cracks as it shrinks during the initial setup. Almost all garage ceilings have a crack right down the middle due to thermal movement, because most garages are not temperature-controlled.
Because the signs of distress are so many and varied, homeowners should be aware of a group or pattern of signs instead of just one. For example, a series of cracks in a particular part of the home can indicate foundation movement, especially if it is accompanied by high or low areas of the foundation.
How do we determine high and low areas of the foundation? I am glad you asked!
The relative elevations of a home foundation can be measured with a manometer or zip level. This is essentially an elevated water tank with a hose connected to it. At the end of the hose is a 6-foot stick with a ruler on it. This instrument allows the inspector to walk around and record the various elevations relative to the tank location. Relative meaning it tells the higher and lower areas of the floor and foundation. (Nothing is absolute because there is no benchmark that can be relied on over time.}
In summary, a pattern of damages in high or low areas is usually a sign of foundation or floor movement.
Classification of Damages
Generally, there are three types of damages. Structural, Functional (or Serviceability), and Cosmetic. Structural damage is rare, even with a multitude of signs of stress. There is typically enough redundancy in home construction to alleviate the concern of structural instability from soil movement.
Cosmetic damage is on the other end of the scale. Minor cracks from the growing and shrinking of materials as they heat and cool or one-time materials shrinkage are, by definition, minor concerns.
Most discussion revolves around functional or serviceability damage. I once had an engineer who worked exclusively for home builders try to assert that if damage is not structural then it must be cosmetic, as if there were no such thing as serviceability problems! Serviceability problems are things like doors and windows not operating properly, cracks that open and close regularly, wide cracks that let pests in or bypass insulation or moisture, damage that would interfere with a real estate transaction, etc.
This classification is somewhat subjective and lends itself to abuse by the wrong people, but there are tools for a more objective evaluation out there. The Post Tensioning Institute has published a widely accepted, albeit flawed, method of measuring tilt and deflection. While flawed, it is better than the hack that I heard a foundation salesman say once: “On a scale of one to 10, your foundation is an 8.5.” I wondered what scale that was and how he arrived at 8.5. In private, the answer was “I arrived at 8.5 by my 30 years of experience … and the fact that my kids need braces.” More on that later.
Soil types and how they affect foundations
Soils are complicated. There are many layers, like a seven-layer chip dip. These layers are non-uniform in thickness, levelness, mineral content, density, and other characteristics. Water moves through them differently and affects them differently. Over time, moisture can change paths under the surface.
For our purposes here, we want to classify soil as non-clay and clayey. Non-clay would be sand, silts, gravels, etc. Clay soils are typically smaller in size by many orders of magnitude, because clay particles are so small they can only be seen with a scanning tunneling microscope. Expansive clay soils, such as montmorillonite, have an affinity for water. They literally suck! Engineers call it negative pore pressure. Clay particles are a naturally occurring negatively charged ion while water is a naturally occurring positively charged ion. Because they are attracted to each other, expansively clay soils tend to swell when exposed to water as the water attempts to position itself between clay particles.
Non-clayey soils are a simpler mechanism to understand in relation to foundations. As sands and silts consolidate, whatever is on top of them (houses, etc) will settle. Often, when exposed to water, the consolidation can occur, and often over time, consolidation will reach its limit, slowing and eventually stopping the settlement of any structures on top of these soils. Clay soil can be more difficult to understand and treat. They can expand with additional moisture, and contract on drying. We have all seen desiccated clay soil. The cracks occur when the clay shrinks as it dries up. This can happen cyclically with seasonal differences in moisture.
When most people think of damage from foundation movement, they tend to think of settlement. This is a result of the marketing by the foundation industry. In fact, when clays swell, they can be very damaging. They can break concrete and bend steel. It is usually referred to as expansive soil heave. I have seen houses heave nine inches on one end. I have examples and more info in my book.
This brings me to my next point: It is not just movement that causes the most problems, but rather differential movement. This is where one part of the home settles or heaves and the other does not. Or where one part settles and the other part heaves. If the whole house went up or down, damage would be minimal…perhaps just the connecting infrastructure (plumbing, electrical, connecting paving, etc).
If the home has a basement, the basement walls can be pushed in towards the home interior as clays adjacent to them expand from added moisture. These forces can easily buckle those walls or push them over, potentially producing serious structural damage.
As mentioned earlier, the majority of homes do not have structural deficiencies. Rather the damage is mostly functional or serviceability issues. But how can you know with confidence how bad each home is individually? Read on!
Who should you call for an opinion?
Most people who have questions about damage they see in their own homes, call foundation repair companies. This is again due to the marketing of the foundation repair industry. This can be a very lucrative industry and the firms in this industry spend millions of dollars constructing the narrative and positioning themselves as the one to call. Certainly these guys are the ones to call to get the actual repairs constructed, however as a 35-year veteran in the foundation repair industry having owned both a foundation repair operation and a registered engineering company, I can tell you that it is not in your best interests to call a foundation repair contractor for diagnoses and possible repair plans and specifications.
I highly recommend that homeowners call an independent forensic foundation engineer. Now that is a mouthful! Let’s break that down a little:
Foundation Engineer: Typically civil engineers are trained in this area. More specifically, geotechnical engineers are best for understanding soil conditions and structural engineers are best for understanding how the structure reacts to the movement of the foundation. Forensic means professionals who engage in understanding how existing soils and structures and reacting to changing conditions. Most civil engineers are engaged in commercial, transportation, and industrial work and most of that is in new construction. Comparatively few engineers are focused on residential work and very few of those engage in forensic work.
It is important to make sure that the engineer engaged has both geotechnical and structural qualifications and especially extensive forensic qualifications. They should know how to write a report and draw up plans and detailed specs that foundation repair contractors can readily install. By this, I don’t mean dabble in forensics once in a while, but rather do it every day or close to it. I can’t tell you how many crappy reports are put out by the original designer or by a relative or friend not engaged in forensics.
Independent. The professional should not receive most of their income from either foundation repair companies nor from home builders nor insurance companies. If they do, they are not really independent, and their judgment is most likely suspect for objectivity.
Why independent forensic foundation engineers as opposed to foundation repair companies?
Foundation repair companies are easy to find and they charge very little or sometimes even nothing for their analysis. There are two main reasons for not calling foundation repair companies for the initial analysis.
- Foundation repair companies utilize foundation repair salespeople and give them various titles to obscure their real title: Sales. They are not qualified to understand soil mechanics or structural load paths. Most of the education these salespeople receive is from their single source supplier, who trains them to recognize issues through the lens of this supplier’s solutions. Since none of these suppliers provide products for expansive soil heave, the training and understanding of heave these salespeople have is practically nonexistent.
When standing in a home and looking with the naked eye, it is almost impossible to tell the difference between settlement and heave, as the signs of distress are almost identical and can only reliably be differentiated by using the many tools available to engineers. Abraham Maslov once said, “If your only tool is a hammer, all of your problems start looking like nails.”
Engineers have 4-5 years of education, 3 years of apprenticeship, and 2 very difficult exams. In addition, they are overseen by technical state boards to ensure that they maintain ethical standards and do not stray too far from their areas of expertise. You get none of these protections with foundation repair sales people.
- Foundation repair sales people are almost always paid on a commission basis. This means that their objectivity is seriously in question, to say the least. Engineers by law cannot be paid this way. The standard formula in the industry for salespeople is 100% commission. This means they only eat if they sell. But even when the pay is different, there is tremendous pressure for sales people to perform. For the tiny minority that are paid salary, there is even more pressure: Those who don’t perform lose their jobs very quickly.
No one would go to a pharma sales person to get their health condition diagnosed instead of a licensed professional doctor. For the same reason, people should not go to commissioned sales people to get their foundation diagnosed for everything they can “find.” I go into this in more detail in my book.
Independent forensic foundation engineers are harder to find and cost more. In the end they should provide you a plan that can be bid apples-to-apples by multiple contractors, and more money will be saved. Additionally, you will likely end up with an accurate diagnosis that is data driven, and the severity will be accurately communicated. It may be that no or very little work at all is needed! Don’t get nailed by someone who only has a hammer for a tool!
Editor’s Note: RK Bob Brown is the author of Foundation Secrets. He is an author, speaker, patented innovator, and the foremost authority on foundation repair diagnosis. As an insider with more than 35-years-experience, he brings transparency, accountability, and engineering efficacy to an otherwise opaque industry. He holds a Bachelor of Design Science from ASU’s School of Architecture and a Bachelor of Science from ASU’s School of Business specializing in Real Estate and Finance. He founded Arizona Foundation Solutions in 1989 and built one of the only foundation repair companies to utilize licensed professional engineers on the front end to analyze initial conditions, make recommendations, and specify repairs before presenting proposals.