Concrete cracks. That’s not a sales line. It’s just what concrete does. It shrinks as it cures, it moves with heat, and it moves with the ground under it. A patio with a few cracks is normal.
What matters is why it cracked, whether it’s still moving, and whether the same thing is happening under your house. Let’s go through it.
Flatwork is not your foundation
Flatwork means the concrete outside: patios, walkways, pool decks, driveways, garden paths. It’s usually thinner than a house slab. It often has little or no steel. It sits on whatever soil was there or whatever got dumped and leveled.
Your house foundation is different. It was designed, permitted and inspected. It has footings that go down into the ground.
So a cracked patio does not mean your house has a problem. But the patio sits on the same ground. That makes it a pretty good early warning system.
What’s under Poway concrete
Poway has two very different kinds of ground. It matters which one you’re on.
- Granite country. Much of the higher ground around Mt. Woodson and the north side sits on granitic rock. Weathered granite breaks down into decomposed granite, or DG. It’s sandy and doesn’t swell much. Problems here usually come from water washing out the base or from fill that wasn’t compacted.
- Clay and fill. The City’s Public Safety Element points to fill soils from the Friars and Mission Valley formations as the main materials involved in fill settlement and expansive soil problems. Those soils show up in parts of the city, not everywhere. Where they are, clay swells when wet and shrinks when dry. Concrete on top gets lifted and dropped.
If you don’t know which you have, look at a hole in the yard. Gritty, tan, sandy soil is likely DG. Sticky, dark soil that cracks in summer is likely clay.
Reading the cracks
Here’s what common patterns usually mean.
- Thin cracks in a straight line, at control joints. That’s the concrete doing its job. Control joints are there so it cracks in a neat line.
- Random hairline cracks. Usually shrinkage. Cosmetic.
- One side higher than the other. That’s a trip edge. Something lifted or dropped. Clay, roots or washout.
- A slab tipped toward the house. Bad news for drainage. Water now flows to your foundation.
- Gaps opening between the patio and the house. The patio is settling or sliding away. Check for washout or fill settlement.
- Pool deck pulling from the coping. Could be soil movement, could be a leak. Check the pool’s water loss.
Do this first
Most flatwork problems start with water. Fix the water before you fix the concrete.
Do:
- Walk the yard during a hard rain and watch where water goes.
- Point downspouts away from slabs and toward a safe outlet.
- Fix sprinklers that spray onto concrete or soak the edges.
- Clear area drains and pipes. The County’s drainage flyer says to inspect and clean private drains before each rainy season, October through April, and after storms.
- Check that ground next to the house drains away. The residential code calls for 6 inches of fall in the first 10 feet for lots around a house.
- Mark crack ends with a pencil and a date. Recheck monthly.
Don’t:
- Don’t seal a crack and call it fixed if water is still getting under the slab.
- Don’t pour a new patio on top of a tipped one without fixing the slope.
- Don’t let a patio slope toward the house. Ever.
- Don’t plant thirsty trees right next to walkways.
- Don’t ignore a gap between a patio and the house wall. Water goes straight down it.
Permits and grading
People ask about this a lot. Here’s what the City says.
The City’s building permit FAQ says that, with limited exceptions, a building permit is required any time you construct, alter, add to, repair or demolish a structure in Poway. Patio covers, retaining walls and pools need building permits, according to the grading page.
The grading page lists when a grading permit is required: excavations 2 feet or deeper with slopes steeper than 2:1, moving 50 cubic yards or more, changing drainage patterns, or working in open space or easement areas. There’s an exemption for minor landscaping grading on developed lots, but it has conditions. One of them is that the work can’t be in an area where a structure is planned, and the page specifically lists patios. Another is that it can’t change drainage as it leaves or enters neighboring properties.
So if replacing your patio means regrading the yard or changing how water drains, check with the City first. Don’t guess.
When it’s a house problem
Here’s when we’d want to look at the house too:
- Cracks in the patio line up with cracks in the house slab or stucco.
- Doors and windows on the same side start sticking.
- Floors inside slope toward the same corner the patio dropped.
- The gap between patio and house keeps growing.
- You see fresh cracks in the garage slab along with the patio.
Any of these suggests the ground under the house is moving too. Our slab foundation repair page covers how that’s evaluated. If clay is the likely cause, see expansive soil foundation repair. For water problems, start with foundation drainage.
Check it once a year
Pick a dry day in early fall. Walk every patio, path and driveway. Look for:
- New cracks, or old ones that got wider.
- Edges that lifted or dropped.
- Water stains or dirt lines that show where runoff goes.
- Joints that opened up next to the house.
Take a photo of each one with something for scale, like a coin or a tape measure. Next year, take the same photo. That’s your record. It tells you if the slab is still moving or if it settled years ago and stopped.
Repair or replace
Short answer: depends on why it failed.
- Cosmetic cracks: clean and seal, or leave them.
- Small trip edges: grind, or lift if the base is sound.
- Big tilts or washouts: usually remove, fix the base and drainage, and re-pour.
- Clay sites: thicker base, better drainage, and joints in the right places help. Nothing makes concrete immune to clay.
How we help
We look at the flatwork, the house, the soil and the drainage together. We coordinate with licensed engineers as needed when movement points to the foundation. Cost depends on how much concrete is involved, access, soil conditions, drainage work and permits. We go over those once we’ve seen the lot. We serve all of Poway, from Old Poway to Green Valley and the hills.
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