Foundation care · the wet side
Foundation drainage & French drains: the other half of protecting your slab
There's a guide on this site about watering your foundation — keeping the clay under your slab from drying out and shrinking. This is the opposite guide. Because on North Texas clay, a foundation gets into trouble two ways, and they pull in opposite directions. Dry it out and the soil shrinks and the slab settles. Soak it and the soil swells and the slab heaves. Watering handles the first. Drainage handles the second. Most homeowners only ever hear about one. Here's the whole picture — and an honest way to tell which problem is actually yours.
Water pooling against your house after a rain is not a watering problem — it's a drainage problem, and adding more water would make it worse. Before anyone sells you a buried drain, the first two questions are always: where do your downspouts let out, and which way does the ground slope? Fix those and a lot of "drainage problems" disappear for the price of a Saturday.
A foundation on clay moves two ways
The ground most of North Richland Hills, Hurst, Watauga, Haltom City, Keller, and Southlake sits on is expansive clay — Blackland Prairie soil that behaves less like dirt and more like a sponge. When it takes on water it swells. When it dries it shrinks and cracks. Your slab is riding on top of that, and it goes wherever the clay goes.
That gives you two completely different failure modes, depending on the season:
- Too little water — the dry side. Through a Texas summer the clay around the perimeter dries fastest, shrinks, and pulls away from the slab. One part of the house loses its support and settles. That's the problem a foundation drip system is built to prevent — it keeps a steady band of moisture in the soil so the clay never gets a chance to shrink away.
- Too much water — the wet side. After a heavy rain, or where a downspout dumps, or where the yard slopes back toward the house, the clay along the foundation stays saturated. Saturated clay swells and pushes — up and sideways — against and under the slab. That's a drainage problem, and it's what the rest of this page is about.
Here's the part almost nobody explains: these aren't either/or. A single house can have a sunny corner that dries out and settles in August and a back wall that sits in soaked soil every spring. The slab gets pulled down on one side and shoved up on the other. That back-and-forth — engineers call it differential movement — is exactly what opens the cracks in your drywall, sticks your doors, and steps the brick over your garage.
If you have a wet problem and someone installs a watering system, you've just made it worse. If you have a dry problem and someone sells you a French drain, you've spent thousands pulling moisture away from a slab that needed more, not less. Getting the direction right is the whole game. That's why the first real tool on this page isn't a product — it's a way to figure out which side you're on.
Which problem do you actually have?
Answer these the way your house actually behaves. There's no email wall and nothing to buy at the end — it just gives you an honest read on whether you're looking at a moisture problem, a drainage problem, or both, so you walk into any conversation knowing which way the water is going.
Answer the five above
As you tap, I'll tell you straight whether you're looking at the dry side (a watering problem), the wet side (a drainage problem), or both — and where to go next. No sign-up, nothing to buy.
This is a guide, not a diagnosis. If you have active, worsening foundation movement, start with a structural engineer. This tool points you in the right direction — it doesn't replace eyes on your actual soil.
Want to do it the old-fashioned way? It takes about fifteen minutes and a rain. An hour after the rain stops, walk the entire perimeter and note anywhere water is still standing or the ground feels spongy within about five feet of the slab. Then find where every downspout lets out. Then look at how the dirt meets the house — it should fall away, not toward. That walk tells you most of what a first visit would.
What standing water actually does to a slab
"Water near the foundation" sounds vague and harmless. The mechanism isn't. When clay along the foundation stays saturated, two things happen. First, it swells — and swelling clay generates real force, pressing up under the edge of the slab and in against it. That's hydrostatic pressure, and it doesn't take a flood; it takes time and a soil that won't let go of water. Second, saturated clay loses bearing strength, so the same soil that's pushing up in one spot can let the slab sink in another once it finally dries.
The result is the same family of symptoms you get from the dry side, which is why people mix them up: diagonal cracks above doors and windows, doors and windows that stick, gaps at the top of interior walls, cracked tile or separating baseboards, and stair-step cracks in exterior brick. The tell is timing. Dry-side damage worsens in the long heat of summer. Wet-side damage worsens after the rains. When it's both, you've got both problems — and they take turns on your house all year.
There's a more expensive failure hiding behind the cosmetic one. When a slab heaves and settles repeatedly, it moves the plumbing that runs through it. A cracked sewer line or supply line under the slab is its own four- and five-figure repair, and it usually shows up long after the drywall cracks did. Managing the water is cheap insurance against the part you can't see.
The fixes, cheapest first — in the order an honest person recommends them
The drainage industry has an incentive to jump straight to the buried, expensive solution. Most yards don't need to start there. Here's the order that actually protects your money:
- Downspout extensions — first, always. Roof water is enormous: a single inch of rain on an average roof is over a thousand gallons, and a downspout emptying next to the slab puts most of that straight into your foundation soil. Getting that water four to six feet out — by surface extension or a buried pop-up — is the cheapest fix in drainage and solves a startling number of "foundation" complaints outright.
- Grading and slope — second. The ground should fall away from the house, not cup toward it. Years of settling, flowerbeds built up against the brick, and mulch piled high all quietly reverse the grade and aim water at the slab. Re-establishing a fall away from the foundation fixes a lot before anyone digs a trench.
- Surface drains (channel/area drains) — third. If water is running across a hard surface — sheeting off a driveway, pooling on a patio, racing down a side yard — you catch it at the surface with a channel drain or area drains and pipe it away. This is a surface problem with a surface fix.
- A French drain — last, and only when the soil itself is the problem. When you've handled the roof water and the grade and the soil still stays saturated for days after rain, that's when a buried drain earns its cost. It's for subsurface water — the kind you can't sweep away — not for skipping the first three steps.
Go deeper on any of these: downspouts & grading · standing water near the foundation · French drain vs. channel drain · why French drains fail in clay.
If the first contractor you call wants to dig a French drain before they've looked at your downspouts and your grade, that tells you something about the contractor. The buried drain is the most profitable line item; it should be the last recommendation, not the first.
French drains in clay — why so many fail, and what "done right" means
A French drain is simple in concept: a trench, lined with filter fabric, filled with clean gravel, with a perforated pipe running through it that collects water from the soil and carries it downhill to an outlet. The concept is easy. Doing it so it still works in five years — in clay — is where most of them go wrong.
Clay is the hard mode of drainage. Water moves through it slowly, and the fine particles love to migrate into a drain and silt it shut. A French drain designed for sandy soil — the kind in a generic online how-to — quietly fails here. The usual culprits:
The takeaway: a French drain in North Texas clay is a design problem, not a digging problem. The slope, the pipe, the fabric, the aggregate, and the outlet all have to be chosen for clay and for your specific yard. A crew that gives you a generic answer about "how deep the pipe goes" is giving you a generic system, and generic systems are the ones being excavated and redone a few years later.
French drain vs. channel drain — they solve different problems
These two get used interchangeably and they shouldn't be. They handle opposite kinds of water, and a lot of DFW properties genuinely need both.
Buried. A perforated pipe in gravel and fabric that collects water already in the soil and moves it out. This is your fix for a lawn that stays soggy for days, soil that won't dry near the foundation, and slow subsurface saturation. You don't see it after it's in.
A surface grate, usually set in concrete across a driveway or low spot, that catches water running over the top before it reaches the house and pipes it away. This is your fix for a driveway that sheets water at the garage or a patio that floods. It does nothing for soggy soil — and a French drain does nothing for a flooding driveway.
The trap is solving only half. Put a French drain in the soggy backyard and you've done nothing for the driveway flooding at the front; add a channel drain at the driveway and the back lawn still sits in water. A real assessment looks at the whole property and the path water takes across all of it — because moving water off one spot and onto another (or onto your neighbor) isn't a fix, it's a lawsuit waiting to happen.
Where watering and drainage meet
This is the part that ties back to the rest of what I do. The goal for a North Texas foundation isn't "wet" or "dry" — it's steady. Clay that holds a consistent moisture level doesn't shrink and doesn't swell, and a slab on steady soil doesn't move. Everything on both sides of this is in service of that one idea: keep the moisture even, all year.
That's why the two systems aren't redundant. A drip system adds a measured amount of moisture in the months the clay would otherwise dry and shrink. Drainage removes the excess in the months the clay would otherwise stay soaked and swell. One fills the trough; the other shaves the peak. Together they flatten the swing that's actually moving your house.
And here's a connection most people miss: your sprinkler system can be a wet-side problem in disguise. A leaking valve, a broken head spraying the brick, or beds over-watered right against the slab keep that soil saturated year-round — the same heave problem, self-inflicted. A line that breaks under a driveway can undermine the soil entirely. It's one more reason a working, properly programmed irrigation system matters to the foundation and not just the lawn — and one of the things I check on a wet check.
Keep roof water four to six feet off the slab.
Keep the grade falling away from the house.
Add moisture in the dry season so the clay can't shrink.
Remove moisture in the wet season so the clay can't swell.
Fix irrigation leaks that quietly soak the foundation.
The honest part — what I do, and what I'll tell you straight
My specialty is the water side of foundation care. The moisture systems — the foundation drip that keeps the clay from shrinking — I design and install myself, as a Texas Licensed Irrigator. The drainage side I know cold, because you can't get the water right around a foundation without understanding both halves of it.
So here's the promise, same as everywhere else on this site: come out, I'll read your property honestly and tell you which problem you actually have. If it's the dry side, that's my work. If it's a downspout and a grade you can fix yourself in a weekend, I'll tell you that and you'll owe me nothing. If it's a serious drainage job, I'll tell you what it needs and make sure it gets done right rather than sell you the wrong thing. The free assessment costs you nothing and there's no service-call fee — the worst case is you learn your foundation's fine and go on with your day.
If a structural engineer, inspector, or foundation-repair company has already told you that you have a drainage or moisture issue, bring that. I'd rather build on what a professional already found than guess — and I work alongside those folks all the time.