A Quick Run-Down on Your San Antonio Home’s Foundation: Soil, Movement, Indicators, and Performance

Foundations Are One of the “Big Three”

The three most common concerns home-buyers have when buying a home in the San Antonio area are the roof, the air-conditioning system, and the foundation. I imagine this is similar in most other parts of Texas, because they are all some of the most expensive repairs a homeowner will make and our climate is responsive for extra adversity for all three. Roofs get beat up by a hail-storm periodically, shaving years off their lifespan. Air-conditioning systems, especially cooling systems, are often working 24-7 during the summer time, given a brief break during the fall, and then back to work in the winter time due to so many builders choosing to install heat-pump heating systems (which are basically reverse-cooling systems). We have pages detailing out the inspection process for both of these systems; rest assured, we take a good, hard look at them both.

The foundation is number 3 on this list. The good news is that significantly deficient foundations are, in our experience, much less common than a roof-covering or air-conditioning system that is ready to be replaced. The bad news is that, when we do find a significantly deficient foundation, the repairs are potentially tens of thousands of dollars. Often, when we find a foundation that we feel needs further evaluation from an engineer (a $500+ expense by itself), it means that this home really needs to be priced to sell or the seller needs to make big concessions for the home-buyer to not seriously consider walking away.


What is a Foundation with “Problems”?

The short answer is: too much movement or uneven movement.

There are numerous things that can adversely affect the performance of a foundation, but one of the most common and biggest contributing factors is soil. In San Antonio, we are at the crossroads of two geographic regions: the South-Texas Plains and the Texas Hill-Country. Although the Hill-Country is known for its limestone and bedrock, making for a great base of a foundation if you dig down into it, the soil in the flatter parts of the San Antonio area is, quite frankly, terrible.

A house is heavy; the walls, the roof, the windows, the doors, etc. The job of the foundation is to take all that weight (the “load”) and evenly distribute it to the surrounding earth or soil. Because of this, the soil that your foundation sits on and surrounds your foundation can actually be thought of as a structural component of your home. If the soil changes or moves, then the foundation will with it, which translates to structural movement of the walls and so on.

In time, just about every foundation will move in some form. The problem is when a foundation moves in some areas but not others, known as “differential” movement. Basically, if some parts of the foundation are moving while others are remaining static, the structure is going to react in a way that it was not designed to, and this can cause problems. This movement can be upward movement, known as “heaving”, or downward movement, known as “settlement”. “Foundation settlement” is broadly used to describe all forms of structural movement in a foundation by the uninformed, much like “short-circuiting” is used a laymen to describe just about every electrical problem. A third form of movement that we won’t be discussing in this article because of how rare it is a “tilt”, which is not differential movement at all, but the entire foundation evenly tilting in one direction, leading to a sloping foundation.


What Causes Foundation Movement?

Depending on where you live, lot of things, but here in San Antonio, the primary culprit is soil and water.

The properties of soil change because the water content of the soil changes; how moist or dry the soil is will affect how it reacts or behaves. This is key to understanding how a foundation moves.

Think of our expansive-clay soils like a sponge sitting on your kitchen sink. If you leave the sponge out for a day without using it, the sponge will dry out and shrivel up to a hard puck. Then, as soon as you add water to sponge, it puffs back up and doubles in size or more. Now this is probably an over-simplification of much more complicated soil-dynamics that an engineer or scientist much more educated than I should be explaining, but I think it demonstrates why a foundation will move pretty effectively. When a soil is wetter, it expands and takes up more space than that same soil when dry. When the soil expands or shrinks, the foundation on top of it moves with the soil.

Weather and rainfall dramatically vary depending on the time of the year. The hotter or drier months are going to cause water in the soil to evaporate at a higher rate than during the cooler or wetter months. This translates into soil expansion and contraction. I very commonly hear complaints from clients or home-owners telling me about cracks in their drywall that are visible and present during the summertime (dry/hot season) and are gone in the spring (rainy/less hot season). Something similar that happens is doors that don’t open/close properly or rub against their frame in some seasons, and operate just fine in others. Likewise with windows.

Now, season changes in temperature and rainfall are a major contributing factor towards soil moisture content, but there are plenty of others. Does the home have a sprinkler system installed that is operating? We will typically see the soil around the home to be adequately moist. Is there a large tree or large bushes very close to the foundation? The vegetation may be absorbing more water from the surrounding soil than is being replenished, drying it out. Plumbing leaks, including both water supply piping and drain line leaks very commonly contribute to excessive moisture in an area, leading to heaving.


Potential Indicators of Foundation Movement


There are many potential indicators of prior foundation movement, more so than can be summed up in short article. Interpreting these indicators can be like piecing together a puzzle, explaining the cause of the prior foundation movement was.

Very important to keep in mind that there is no one indicator of foundation movement alone that will tell you to call an engineer. As an inspector, we take in the whole picture of the home and reserve our opinion for the very end of the inspection, when we can put all the pieces together to determine if significant foundation movement (“adverse performance) is occurring.

Drywall Cracks

Drywall cracks, especially around windows and doors, are extremely common indicators of prior movement. While all drywall cracks can be indicators of prior movement and should be monitored, cracks that are diagonal or horizontal are more concerning than cracks that go straight-upwards or are vertical. When looking at a house, look around the corners of the windows and doors and see if you see flat spots in the drywall texture or areas that look like they have been patched or caulked over. Sometimes you can see the crack outlines through multiple coats of paint. Someone may be trying hide the cracks from you.

Cracks in Exterior Brickwork or Masonry

The rules above apply to the masonry veneer of the exterior walls as well. Cracking in brickwork is often indicative of structural movement, but how the cracks form is important to note. While a straight-vertical crack upward should still be sealed to prevent moisture intrusion, it may be a result of thermal expansion of the brickwork, mortar, or framing rather than structural movement in the foundation. Look for stair-step like cracking or horizontal cracking in the exterior bricks and joints. Make note of any patched joints or newer-looking mortar. Painted brickwork is a red-flag.

Difficulty Operating Windows & Doors

Windows and doors are indicators as well. Does a door look out of square, with large gaps between the door and the frame in some areas and not in others? Movement may be responsible, but keep in mind that the person installing the door may also not have done a good job! Does the door rub against the frame? Make note. Does a window only open partly before it opens no further? It could be movement in the window frame due to foundation movement, but it could also be dirty tracks that need cleaning or lubrication, or a worn-out opening mechanism. Look for door strike-plates that have been adjusted or modified, especially in bathroom areas; just because a door closes now doesn’t mean that it always did.

Sloping Floors

This is a big one. During the course of the inspection, if an inspector perceives a noticeable slope in any part of the ground-level floor, we note it and start looking diligently around that area for any other evidence of structural movement. I’ve had instances where the flooring guys just did a terrible job when laying tile and went on a wild goose chase, but sloping ground-level floors are important indicators of adverse foundation performance.

While we’re talking about the ground-level, we formulate the bulk of opinion of a foundation based on the ground-level only. Why is this? Because drywall cracks or doors that rub their frame on the second story may not be the result of foundation movement, but structural movement of the framing, or a result of heavy winds. In reality, not all carpenters frame a structure adequately, and just because the second-floor hasn’t collapsed downward doesn’t meant that it isn’t moving and is adequately supported.

Friezeboard Seperations

Friezeboards are trimboards or casing for the exterior wall, found at the top of the exterior walls just below the soffit. If these trimboards are observed to be separating from the house OR from each other, they may be indicators that a corner of the home is moving upward or downward. Again, friezeboard separations should only be taken into account if the other friezeboard joints of the home appear to be installed in a professional manner. If the other joints are cleanly attached but one corner of the home looks off, then movement is to be suspected. If ALL the friezeboards are separating, then it was probably a poor installation.

These are just a handful of potential movement indicators or indicators of adverse performance.


What do These Foundation Movement Indicators Mean? Am I Going to Need My Foundation Repaired?

As a TREC licensed Home Inspector, it is our duty to give you our non-biased OPINION on the foundation. This is the only part of the report were we are REQUIRED to give you a subjective opinion about a component or system. This is known as the performance statement. After taking into consideration all the various indicators of adverse performance/movement, along with the location of the home, the type of build/build quality, and especially age, we give you our opinion: Yes, this structure is being adequately supported and is performing acceptably, or No, this structure is not adequately being supported by the foundation and we recommend further evaluation by a licensed engineer. While not every opinion will be phrased exactly like that, this is the general sentiment of the performance statement.

Keep in mind that this is the inspector’s opinion. Your inspector most likely isn’t a professional engineer, and if you want a more definitive idea of the condition of the foundation, you’re going to need to call out an engineer. But in my experience, a VAST majority of all foundations in the San Antonio area are performing acceptably, especially the slab-on-ground/slab-on-grade foundations.

By performing acceptably, I mean that they probably don’t NEED to be repaired. This is key: evidence of prior foundation movement is extremely common, especially on older homes, but foundation movement that is so extreme that it is causing significant harm to the structure above it is rare. In our opinion, we don’t think some cracks in the drywall and some doors that don’t open/close properly requires thousands of dollars worth of foundation repair. We think a much more cost-effective approach is calling a carpenter to adjust the doors and calling a painter to touch up the drywall cracks. You may think otherwise, and if so, be prepared to consult with an engineer about foundation repair options.

Pier and beam foundations are a different story, and are noticeably only present on older homes. If you are buying an older home with a pier and beam foundation, the probability of foundation issues is significantly greater. That said, not all pier and beam foundations are deficient, and often we will see evidence of prior adverse foundation performance but see evidence of repairs in the crawlspace, indicating that the previously poor performance may have been addressed. Every home is different.

A final note about foundation repair: nobody in the State of Texas other than a licensed professional engineer can prescribe foundation repairs. Most foundation repair companies are nothing more than unlicensed contractors, and unless they have an engineer on staff performing their evaluations, their estimates will never contain the word “repair”. While a home inspector does have a license and is likely going to be more reputable than an unlicensed foundation repair contractor trying to sell $10,000+ foundation jobs, the only person whose word holds definitive weight is the engineers. They are the only people who can legally say “yes, this foundation is experiencing abnormal movement and should be corrected, and here is what needs to be done…”. If you have any doubts or concerns about the foundation of your home or of a home you are looking to purchase, there is no substitute for contacting a licensed engineer to perform a foundation evaluation.



In summary, foundations may move over time for a variety of reasons; some foundation movement is unavoidable, too much or uneven movement can cause problems for the structure above. Just because your home has experienced movement does not mean that the home is unsafe or unlivable, but you do need to be aware of these indicators and understand what they mean. A home inspector will observe a foundation during an inspection and give you their honest opinion of it (in Texas). Most homes will experience some movement over time, and often, that movement isn’t severe enough to warrant foundation repairs. If you want to know if you need to consider foundation repairs, contact a licensed engineer.


16400 Henderson Pass, STE 517
San Antonio, TX 78232

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Professional Home Inspector Kyle D. Scott

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