I have watched a buyer walk away from a good house over a brick crack you could cover with a pencil. I have also watched a buyer shrug off something that should have sent them straight to an engineer. Foundations in Texas are the single most emotional thing in a transaction, and almost nobody explains them calmly. So here is the calm version.
Start with the fact that reframes all of it: in the four-state region the Census calls West South Central — Texas, Oklahoma, Louisiana, Arkansas — 97.9 percent of new single-family homes are built on a slab. Nationally it is 73 percent. A slab on clay is not a compromise or a cheap shortcut. It is how houses are built here, by engineers, to code, on purpose.
And the ground under that slab moves. That is also normal. The entire question is how much, and that is a question with real published answers.
The clay under most of North Texas contains a mineral called smectite, which absorbs water into its own crystal structure and physically swells. Dry it out and it shrinks back. Houston Black — the state soil of Texas, the signature Blackland Prairie clay — runs 46 to 60 percent clay. In a dry summer it opens cracks that the soil scientists measure at more than four inches wide and a foot deep, and those cracks stay open for 90 to 150 days.
Four inches wide. In the ground your house is sitting on.
Engineers measure this with the plasticity index, and there is a bright line: the Texas Section of the American Society of Civil Engineers defines expansive clay as soil with a weighted plasticity index greater than 15. The Texas Department of Licensing and Regulation uses the same number.
A geotechnical study of the Eagle Ford formation in Irving measured weathered shale with a plasticity index between 43 and 61. That is not a little over the line. That is three to four times the threshold.
The same study turned up the most surprising thing I found while writing this. The active zone — the depth of soil that actually changes moisture with the seasons and therefore actually moves — is conventionally assumed to be five to ten feet. In Eagle Ford clay they measured it at roughly eighteen feet. Close to double the textbook figure.
That single fact explains a lot about why surface-level fixes underperform here and why North Texas movement sometimes outruns what anyone predicted.
Three things you will hear, and they are not interchangeable.
Conventionally reinforced slab. Concrete with rebar in it, poured on grade.
Post-tensioned slab. Steel tendons run through the slab inside plastic sheathing so they do not bond to the concrete. After the concrete cures, those tendons are pulled tight under enormous force, which puts the whole slab into compression. It then resists the tension of soil movement the way a prestressed beam does. Post-tensioning came into residential use in the mid-1960s and got HUD approval in 1968; it is now extremely common in Texas subdivisions.
Two practical consequences of a post-tensioned slab that matter to an owner. Before the tendons are stressed the slab is effectively unreinforced, and there is very little conventional rebar in it to control ordinary shrinkage cracking — so some cracking is baked into the design. And you do not let anyone cut or core into it casually. Plumbers, pool builders, anyone anchoring a safe to the floor: they need to know it is post-tensioned before they pick up a saw.
Pier-and-beam. The house sits on piers over a crawl space. Common in older Fort Worth neighborhoods, rare in anything built here in the last forty years. Easier to access plumbing, easier to adjust, and a different set of things to inspect.
This is the section most Texas foundation articles get wrong, because they invent numbers. So I am going to quote the engineers directly and tell you exactly what the numbers do and do not mean.
The Texas Section ASCE publishes free, public Guidelines for the Evaluation and Repair of Residential Foundations. On cracks, it says something worth having on a plaque:
“the majority of cracks do not compromise structural integrity.”
On whether a homeowner has to do anything about movement, it says an owner may reasonably choose “periodic cosmetic repairs and door adjustments, rather than comprehensive foundation underpinning.” That is an engineering body, in writing, saying that living with it is a legitimate option.
| Observation | What the source says |
|---|---|
| Hairline cracks, 1/64″ or smaller | Generally acceptable; usually initial settling |
| Floor slope over 1 percent | “Usually noticeable” |
| Floor slope over 2 percent | Beyond what accessibility standards allow on a public walking surface — used as a comparison, not a code requirement for a house |
| Brick veneer gaps ¼″ or larger | Flagged |
| Diagonal cracks in drywall | “Significant indicators of excessive foundation movement” |
You will also see L/360 quoted as though it were a legal threshold in Texas. It is not. It is a live-load deflection limit borrowed from the residential building code, and the ASCE guideline offers it as an analogous screening benchmark, with careful wording: if a foundation profile shows deflection under that limit, it is “unlikely the foundation is deflected materially unless visible indications show otherwise.”
Unlikely to be materially deflected. Not “fine.” And crucially, the same document warns twice against relying on measurements alone: a floor elevation survey “should not be the only basis” for evaluating a foundation, and caution is advised over short spans because “built-in unevenness can dominate.” Concrete is poured by people. Not every dip is the earth moving.
You will also see a rule of thumb that more than a quarter inch of slope over four feet means trouble. Be careful with it: a quarter inch over four feet is about half of one percent, which is less than the one percent the guideline calls merely noticeable — and four feet is exactly the short span the engineers warn against reading. A localized dip over a few feet is usually floor finish, not the earth.
Every one of these is about the same underlying goal, and if you remember nothing else, remember this: you are managing consistency, not volume. Clay is damaged by the swing, not the moisture. A foundation kept evenly damp year-round is in better shape than one that is drenched in August and bone-dry in September.
The Texas Section ASCE puts real numbers on it: top of concrete at least eight inches above the adjacent soil, ground sloping away at a minimum of five percent across the first ten feet and two percent beyond that, no drainage swale within four feet of the foundation, and planting beds sloping away at least two inches per foot with edging that lets water out rather than ponding it against the house.
Five percent over ten feet is six inches of fall, which is also what the residential code requires. Two independent sources, same number. Of everything on this list, grading is the cheapest to fix and the most commonly wrong.
And here the engineers disagree, so I will give you both rather than split the difference. The Texas Section ASCE says downspouts should extend at least two feet away from the foundation and past any adjacent planting beds. The Foundation Performance Association says five to ten feet.
Two feet is the floor. Farther is better. Nobody argues for less.
I want to be straight with you about this one, because it is the most confidently repeated and worst-sourced advice in Texas real estate.
The specific recipe you have heard — soaker hose two feet out, fifteen minutes, four times a week — I could not trace to any engineering body, university extension service or state agency. It is attributed to unnamed experts. And the famous homeowner's guide on foundation watering that gets cited as Texas A&M is actually CSIRO, the Australian national science agency. Different continent, different clay, and not who people think they are quoting.
Here is what actual engineering sources say. The Foundation Performance Association: irrigate at least one to two feet away from the foundation, keep the system on manual and run it in dry periods when you see wilting rather than on a fixed calendar, apply it “as equally as possible on all sides,” and never let sprinklers spray against the structure. If the soil has already pulled away from the slab, do not pour water down into the gap.
And a genuine dissent worth knowing: the Texas Section ASCE's own maintenance appendix does not recommend foundation watering at all, and the main document warns that “excessive watering of soil adjacent to the structure can also result in foundation heave.” Colorado State's extension service, on similar clay, says keep sprinklers five feet out and regulate water near the foundation.
Reconcile them like this: everyone is aiming at stable moisture. Nobody is aiming at wet. Overwatering is a real failure mode that pushes the slab up, and a slab pushed up is not better off than a slab settled down.
A mature tree is a pump. It pulls moisture out of the soil in its root zone all summer, and if that root zone runs under the corner of your house, it is drying the clay under your foundation.
How far is far enough? Sources genuinely disagree. The Foundation Performance Association says a broadleaf tree should be at least its own mature height from the house; Colorado State says fifteen feet; the Texas Section ASCE gives no number and just says avoid large vegetation near foundations, judging by water demand and mature size. For a forty-foot pecan those give wildly different answers, and I would rather tell you that than pick one.
You will find lists online of the “worst trees for Texas foundations.” Every one I checked was published by a company that sells foundation repair, and I could not find a single authoritative species ranking. Judge a tree by how much water it wants and how big it gets, not by a list on a contractor's blog.
A leaking supply or drain line under a slab dumps water into exactly the soil you have been carefully trying to keep stable. The Texas Section ASCE lists leaking plumbing among the factors that drive foundation performance and warns that leaking utility lines can cause heave. If your water bill jumps, if you hear water running with everything off, if one patch of the slab is inexplicably warm — chase it down.
Here is a distinction that resolves most of the confusion I see, and it comes straight from the rules.
Under the TREC Standards of Practice, a Texas home inspector is required to “render a written opinion as to the performance of the foundation.” Is it performing, or is it not. That is their job and they must do it.
But the same rules say an inspector is not required to determine the cause or source of a condition, and may not provide engineering services. And the Texas Board of Professional Engineers and Land Surveyors is explicit that “analyzing the cause of a condition, recommendations for repair, or providing any other expert engineering opinion associated with a foundation” is the practice of engineering and requires a licensed P.E.
Less than the name suggests, and the Foundation Performance Association says so directly: repair companies offering a lifetime transferable warranty typically warrant only the work they did and the components they installed, not the entire foundation. Cracked tile and drywall are commonly excluded.
And then the part that should make a Texas buyer sit up: these warranties “may not cover repair of the foundation when movement is caused by uplift.”
Uplift. Heave. On expansive clay, in North Texas, one of the most common ways a foundation moves at all. Read the exclusions before you treat that warranty as protection.
The Texas seller's disclosure notice asks about Foundation/Slab(s) and, as its own separate line, Previous Structural or Roof Repair. It asks what the seller is aware of. Prior foundation work is squarely disclosable, and the paperwork — the engineer's letter, the repair plan, the warranty, the post-repair elevation survey — becomes part of the story.
A repaired foundation is not automatically a problem. A repaired foundation with no engineer involved, no documentation and no explanation of why it moved is a different conversation. Ask for the paperwork. If it does not exist, that tells you something.
Because the published figures do not agree and everyone publishing them has a stake.
| Source type | Typical DFW slab repair |
|---|---|
| A foundation repair company | $3,300–$8,500 |
| An engineering firm | $8,000–$25,000 |
Those barely overlap. And the incentives run in opposite directions: the contractor's lower number wins the bid, the engineer's higher number strengthens the case for hiring an engineer first. I found no government, academic or insurance dataset on DFW foundation repair costs. There is no neutral number to give you.
For an engineer's evaluation, marketplace-reported figures in the Dallas area run roughly $350 to $900 for a structural report, more for a full evaluation with an elevation survey. That is self-reported data, not survey data. Call two firms and get real quotes.
“Run a soaker hose against the slab every day all summer.” Watering right against the concrete can oversaturate the bearing soil and push water down the exterior beam, which moves things in the wrong direction. The Texas Section ASCE warns in writing about heave from excessive watering next to the structure. Consistent, not soaked. Away from the slab, not against it. Driven by conditions, not by a timer.
“Just get the free foundation inspection from a repair company.” A free evaluation from a company that sells the repair can be useful, and plenty of them do good work — some employ or retain a licensed engineer precisely so their opinions are proper. But it is not an independent opinion, and under Texas law a causation opinion and a repair recommendation are the practice of engineering, which requires a P.E. So ask whether one is involved. And if the answer is going to change your offer or your budget, hire your own engineer. It is the cheapest money in the whole process.
None of this is a reason not to buy a house in Texas. It is a reason to know what you are looking at, which is a much better position than being scared of it.
One more time, because this post gives specific numbers: I am a REALTOR, not an engineer. Everything here is general information drawn from published engineering guidance, and none of it is an engineering opinion about your house. For that you need a licensed professional engineer who has actually been to your address.
Cracking is extremely common and usually not structural. The Texas Section of the American Society of Civil Engineers states in its published guidelines that the majority of cracks do not compromise structural integrity, and the Foundation Performance Association treats hairline cracks of 1/64 inch or smaller as generally acceptable and most often related to initial settling. What matters more than any single crack is whether it is changing: a crack that is visibly wider than it was a year ago, a door that stops closing and never comes back, or diagonal cracking in drywall are the things worth a professional opinion. Confirm the condition of any specific house with a licensed inspector and, where cause matters, a licensed structural engineer.
Because of the clay. Much of North Texas sits on soil containing smectite, a clay mineral that absorbs water into its structure and physically swells, then shrinks when it dries. Houston Black, the state soil of Texas, runs 46 to 60 percent clay and opens cracks in dry weather that soil scientists measure at more than four inches wide and twelve inches deep, staying open for 90 to 150 days. Engineers classify soil as expansive above a plasticity index of 15; measured samples of weathered Eagle Ford shale in the Dallas area ran 43 to 61. The houses are not built badly. The ground genuinely moves. Confirm soil conditions for a specific address with a geotechnical or structural engineer.
Cautiously, and the popular recipe is not well sourced. The specific advice you often hear - soaker hose two feet out, fifteen minutes, four times a week - could not be traced to any engineering body, university extension service or state agency, and the widely cited homeowner guide on the subject is actually from CSIRO, the Australian science agency, not Texas A&M. What engineering sources do say: the Foundation Performance Association recommends irrigating at least one to two feet away from the foundation, keeping the system on manual and running it in dry periods rather than on a fixed schedule, applying water as equally as possible on all sides, and never spraying against the structure. The Texas Section ASCE's maintenance guidance does not recommend foundation watering at all and warns that excessive watering next to a structure can cause heave. The common principle is stable moisture, not wet soil. Confirm an approach for your own house with a structural engineer.
The Texas Section ASCE recommends the top of the concrete sit at least eight inches above adjacent soil, with the ground sloping away at a minimum of five percent across the first ten feet and two percent beyond that. Five percent over ten feet works out to six inches of fall, which matches the residential building code requirement. No drainage swale should sit within four feet of the foundation, and planting beds should slope away at least two inches per foot with edging that lets water drain out rather than pond against the house. On downspouts the sources differ: the Texas Section ASCE says extend them at least two feet from the foundation and past any planting beds, while the Foundation Performance Association recommends five to ten feet. Two feet is the floor and farther is better. Confirm specifics for your lot with a licensed professional.
Yes, and the scope is narrower than most buyers assume. Under the TREC Standards of Practice a Texas inspector is required to render a written opinion as to the performance of the foundation - whether it is performing or not. But the same rules state an inspector is not required to determine the cause or source of a condition, and may not provide engineering services. The Texas Board of Professional Engineers and Land Surveyors is explicit that analyzing the cause of a foundation condition or recommending repair is the practice of engineering and requires a licensed professional engineer. So the inspector tells you whether; a structural engineer tells you why and what to do. Confirm scope with your own inspector before the inspection.
No, and the gap matters in Texas. The Foundation Performance Association states that repair companies offering a lifetime transferable warranty typically warrant only the work they did and the components they installed, not the entire foundation. Cracked tile and drywall are commonly excluded. Most significantly, such warranties may not cover repair of the foundation when movement is caused by uplift - and uplift, or heave, is one of the most common ways a foundation moves on the expansive clay found across North Texas. Read the exclusions in the actual warranty document before treating it as protection, and confirm the terms with the issuing company in writing.
The Texas seller's disclosure notice asks the seller about Foundation/Slab(s) and includes a separate item for Previous Structural or Roof Repair, along with a general question about whether the seller is aware of any item in need of repair. The form is built around the seller's awareness. Prior foundation work is squarely within what it asks about, and in practice the supporting paperwork - the engineer's letter, the repair plan, the warranty and any post-repair elevation survey - becomes part of what a buyer will want to see. A repaired foundation with complete documentation is a very different conversation from one with none. Confirm your specific disclosure obligations with your agent and a real estate attorney.
Worried about a specific house? Send me the address. I will tell you what I see, what I would want an engineer to look at, and whether it is the kind of thing that should change your offer or just your expectations. I am not going to talk you out of a good house over a brick crack, and I am not going to talk you into a bad one either.
Ask me about a houseChecked September 2026. Where sources disagree I have said so in the text rather than quietly picking one. Laws, rates and standards change — verify anything you are relying on with the relevant agency or a licensed professional.
REALTOR® · BHHS PenFed Realty Texas
I help buyers and sellers across the Dallas–Fort Worth Metroplex — Fort Worth, Burleson, Crowley and Keller, and the surrounding Dallas area. I write these because they are the questions I answer on the phone every week, and most people never get a straight answer to them. If you have one I have not covered, ask me — I will probably turn it into the next post.