A slab house has no crawl space. The concrete floor rests right on the pad, and its thickened outer edge does the job of a footing. That makes a slab simple and sturdy, and it also means that when the ground under it moves, the floor you walk on moves with it. Poway Structural repairs slab foundations across the city. Some slab jobs need stamped plans. For those, we coordinate with licensed engineers as needed.
Forty-plus years on a 1970s slab
Census estimates count roughly 16,900 homes in Poway. About 6,200 of them were built in the 1970s, more than a third, and about 3,700 more in the 1980s. The City’s history marks the first subdivision, Poway Valley Homes, in the late 1950s, Lake Poway’s dam in 1971, and incorporation in December 1980.
Tract homes of that era were commonly built slab-on-grade. That’s a pattern, not a count, because nobody has published foundation types for Poway. We confirm yours on site. Either way, many Poway slabs have now been through four or five decades of wet winters, dry spells, and changing yards.
Four things that move a Poway slab
The line between cut and fill. Tract pads on sloped ground were often cut on one side and filled on the other. The City’s Safety Element says fill derived from the Friars and Mission Valley formations is the main material in local fill settlement. If the fill side compresses, that part of the slab drops, and a crack tends to run along the boundary. See fill settlement repair.
Clay at the edges. Where the soil or fill holds expansive clay, the outer edge of the slab rides up when the ground gets wet and settles back when it dries. The middle, protected by the house, changes less. See expansive clay.
Water from below and beside. Older slabs often have original copper or cast-iron lines under them. Water escaping from one of them wets a single patch of ground, and that patch can sink or rise. Outside, a planter against the wall or a sprinkler that sprays the foundation does the same thing slowly. The Safety Element lists over-irrigation and leaky pipes among its saturation triggers.
The room someone added later. A family room or garage conversion poured next to the original slab rests on its own footing. The joint between them is a natural place for a crack.
Every slab also has shrinkage cracks from curing. Those are normal and usually stay the same.
Around the house, room by room
In the kitchen and baths, tile is a good early warning. A line of cracked tiles running straight across a room often follows a slab crack underneath. In the garage, look for a crack where one side sits higher, or a gap growing under the garage door on one end. At doorways, watch for thresholds that no longer sit flat and doors that start to rub. And don’t ignore the water bill. A warm patch on the floor, or a bill that jumped for no reason, can mean a hot water line leaking under the slab.
How we diagnose a slab
We start with a set of floor elevations taken through the whole house and drawn as a contour map. Then we set that map beside a sketch of the lot. If the low half of the floor sits over the downhill half of the pad, fill is the first suspect. If the rim of the house reads higher than the rooms in the middle, the clay under the perimeter has probably taken on water. A rim that reads lower than the middle points the other way, to soil that dried and pulled back. A lone bump in one room makes us think of a pipe, and a sudden drop at the doorway to a family room makes us think of the addition’s footing.
We also check where the downspouts go, how the yard sheds water, and whether the City has grading or soils records for the tract. When a plumbing leak is on the list of suspects, we have it tested first, because there’s no point supporting a slab while water keeps running under it.
Repair choices, lightest to heaviest
The lightest fix is often water: regrading, rerouting downspouts, and adjusting irrigation. On clay, that alone can calm a slab. See foundation drainage. Once movement has stopped, cracks get injected or sealed, as covered on the crack repair page.
A step up, a settled section can sometimes be raised or have voids under it filled, when the soil and slab suit it. Heavier still, piers can be installed along the edge that dropped, carrying that part of the house down to firmer soil or rock. See settlement and sinking. Badly broken sections can be cut out and repoured, and an addition joint can be tied together or supported from below.
If you have a post-tension slab
Some newer Poway homes may be on post-tension slabs, with steel cables tensioned inside the concrete. A stamp in the garage warning against cutting is a strong hint. Nobody should drill, core, or saw a PT slab until the cable locations are known, and repairs to one involve an engineer from the start.
City paperwork
Poway’s Building Services handles permits for structural work on a slab. Plumbing under the slab is permitted separately. You’ll know which ones your job needs before we start.
Straight answers
There’s a warm spot on our floor. Is that the slab?
It’s more likely a hot water line leaking under the slab. Get a leak test. The leak can soften the soil under the slab over time, so it’s worth fixing soon.
Is slab jacking an option for our settled patio or garage?
Sometimes. Lifting or void-filling works on some settled sections when the soil below is stable. If the soil is still moving, piers or water control come first.
Our 1970s house has a sunken living room. Does that change slab repair?
Mostly, it changes how we measure. The slab changes level at the edge of that room, and the step is a natural place for a crack. We take floor readings on each level separately and then compare them, so the step itself doesn’t read as a drop.
I’m remodeling. Should I check the slab first?
Yes, especially before new tile or hardwood. Fixing the slab is much easier before the new floor goes down.
Ready when you are
Tell us roughly when the house was built and what the floors are doing.
Sources
American Community Survey 2024 (5-year), City of Poway (year built). City of Poway, Poway History page. City of Poway General Plan Public Safety Element (May 2026): fill settlement, saturation triggers. City of Poway Building Services.