Signs of Foundation Problems: 2026 North Texas Guide

Search for signs of foundation problems and you'll find the same list over and over: bowing basement walls, water seeping through the basement wall, cracks in the cinder block below grade.

But if you live in Garland, you probably don't have a basement. Your house sits on a concrete slab poured straight onto some of the most reactive clay soil in the country, and almost none of that advice applies to it.

This guide keeps the parts that apply everywhere, which are mostly about crack width, and sets the rest aside. Then it adds the one thing national lists leave out. On Texas clay, the most useful sign isn't how wide a crack is today. It's how much it changes between August and April.

The useful change is that you can check the signs of foundation problems yourself, and more accurately than before. Measuring your own floors used to mean hiring someone.

Any phone with a free level app will read the tilt of a floor, and newer iPhones with LiDAR do it more accurately still. Put the phone flat in the middle of a room, write down the tilt, then repeat in other rooms. If one corner reads very differently from another, that's differential settlement, meaning one part of the house has moved more than the rest.

The number to remember is 0.5 degrees, or about 1/4 inch over 10 feet. Below that, a slope is generally accepted. Beyond it, a professional opinion is worth getting.

If you want better accuracy, a 4-foot bubble level runs $15 to $30, and a cross-line laser $40 to $80. The laser projects a level line around the room, and you measure down to the floor at several points. If those vary by more than 1/4 inch over 10 feet, you've found something real.

Soil scientists measure how much a soil swells and shrinks using linear extensibility, which is the percent a sample changes size as its water content changes. Under 3 is low. Over 9 is very high.

The USDA soil survey puts Houston Black under about 32% of Garland, reading 17, with 55% clay. Ferris covers another 16% at the same 17, with 52.5% clay.

That's near the top of the scale. Soil like that doesn't settle once and stop. It lifts when it rains and drops when it dries, year after year, and your slab rides on top of it.

Two things follow from that. First, a house here can show a crack, then show less of a crack, without anything being fixed. Second, the damage that matters comes from differential movement, where one part of the slab rises while another falls. Even movement does far less harm.

It's also why basement-focused advice can mislead you here. There's no wall holding back soil pressure. The way a slab fails is by bending.

Of all the signs of foundation problems, crack width is the quickest thing to check, and you don't need any tools.

• Under 1/16 inch. Hairline. Very common in drywall, and usually the result of normal settling or seasonal expansion of building materials. It's rarely a foundation concern on its own.
• 1/16 to 1/4 inch. The watch-and-wait band. It isn't an emergency, but it isn't something to ignore either.
• Over 1/4 inch. Worth a professional look, especially in brick or at the slab edge.

Inspectors use similar bands. The severity scale published by the British Royal Institute of Chartered Surveyors, credited to W.H. Ransom, calls fine cracks under 5mm slight, 5 to 15mm moderate, and anything over 15mm to 25mm severe. At that point, walls tend to lean or bulge and windows distort.

Width isn't the only thing that counts, though. Two cracks of the same width can mean very different things.

Taper matters more than width

A crack that's wider at one end than the other is telling you the two sides are rotating apart, not just separating. That's a sign of movement, and it's more concerning than a wider crack of even width.

The same goes for direction. In brick, a stair-step crack that climbs the mortar joints follows the weakest path through the wall. It points to one part of the foundation dropping compared with another.

How many cracks, and where, matters too

One crack in one wall is a local event. Several cracks appearing at once in different parts of the house suggest the whole slab is moving, and that deserves a prompt look, however wide any single one is.

This takes two minutes and a pencil, and it beats any amount of squinting.

1. Draw a short pencil line across each end of the crack.
2. Write the date next to it.
3. Measure the width at the widest point and write that down too.
4. Check it once a month.

If the pencil marks stay put for a year, you have a crack that happened and stopped. If the crack keeps creeping past your marks, the movement is still going on. That difference changes what any engineer will recommend, and you can't get it from a single visit.

Keep your record somewhere you'll find it. A dated record over two seasons is genuinely useful evidence, and it costs nothing.

Some signs of foundation problems show up in how a house works, not how it looks. Plenty of people notice a sticking door months before they notice a crack.

A door that used to close cleanly and now catches at the top corner is telling you the frame is no longer square. Windows that stop sliding, or won't latch, say the same thing. On its own, a sticking door can be humidity. Paired with a crack that runs diagonally up from the corner of the door frame, it's a pattern.

Floors are the other early sign. Dropping a marble won't tell you much, because almost every floor slopes a little. It's better to measure, using the phone method above, and compare against that 1/4 inch over 10 feet tolerance.

Nail pops in drywall and cracked floor tile belong in the same group. Neither proves anything alone, but both are worth adding to your dated record.

Brick is rigid and unforgiving, so it usually shows movement before the inside of the house does.

Walk around the house and look for stair-step cracking in the mortar, gaps opening where the brick meets a window or door frame, and any point where the brick above the slab has separated. Gaps wider than about 1/4 inch at windows are worth mentioning to a professional.

Then look down. Where the slab edge meets the soil, you want the ground sloping away from the house. What you often find instead is a gap between soil and slab in late summer, which is the clay shrinking back, and standing water in the same spot after rain.

That cycle is what drives the whole problem. Water reaching a house unevenly is what makes one part of the clay swell while another stays dry.

What to fix before you spend anything

Some of the worst causes are cheap to correct, and they're worth doing while you watch a crack rather than after.

The City of Richardson publishes homeowner guidance on exactly this, and it applies across the clay belt. Water evenly on all sides of the house, so the soil moisture stays even. Keep drainage running away from the foundation, and stop water pooling against it. Let downspouts discharge at least three feet from the foundation.

The one people miss is planting. Trees or large shrubs within 20 feet of the house pull moisture out of the soil unevenly, and in a dry spell that ground may need watering that the rest of the yard doesn't.

None of this reverses movement that has already happened. What it does is remove the cause, so a repair has a chance of lasting, and a borderline crack has a chance of settling down on its own.

Here's the test that matters most on Blackland clay, and it's the one the top-ranking guides we read leave out.

Look at the same crack in late summer and again after a wet spring. In North Texas, clay shrinks through a dry August and swells again with spring rain. A crack that opens and closes on that rhythm is being driven by live soil movement under your house.

The severity table used by the American Society of Home Inspectors ranks this kind of crack as a serious one: signs of active, recent or recurrent movement. It says outright that the movement may be seasonal or ongoing.

That's why a one-off inspection can under-read a house. Someone who visits in March, after months of rain, sees a slab that has been pushed back up and cracks that have partly closed. The same house in September can look much worse.

It's also why the dated record from earlier is worth more here than it would be somewhere with stable soil. You're not just recording a crack. You're recording a cycle.

There are three clear triggers, rather than a vague sense of worry:

• Sudden appearance. Several cracks showing up at once, or one appearing overnight, rather than creeping in over years.
• Measurable slope. More than 1/4 inch over 10 feet across a room, confirmed with a level rather than judged by eye.
• Growth across a season. A crack that has moved past your dated pencil marks since the last time you checked.

Any one of those is enough.

There's a practical reason to involve an engineer early in Garland specifically. The city requires a permit once the value of foundation repair work reaches $2,000, and the permit costs $45. To get it, the city asks for an engineer's letter setting out the planned repairs, a stamped pier diagram, and a foundation and elevation assessment plan. When the work is done, the repair company has to send the engineer's final report confirming the repairs met specification.

In other words, on any real repair in Garland, an engineer is already part of the process. Bringing one in to help diagnose the problem, not just to sign the paperwork, gives you an independent opinion before anyone quotes you.

Work through it in order. Start with width, because it takes no tools: under 1/16 inch is usually nothing, and over 1/4 inch deserves attention. Then look at taper, because a crack wider at one end is rotating rather than just opening. Then check the floors, with a phone and the 1/4 inch over 10 feet rule.

Then do the thing the national lists never tell you to do, and look again in six months. On soil reading 17 for linear extensibility, the signs of foundation problems that matter most are the ones that change with the weather. A single photograph of a crack is a data point. Two photographs, six months apart, are a diagnosis.