You felt it walking across the kitchen, or a chair rocked, or something rolled off the counter and kept going. Now you want to know how long it's been doing that and whether it's getting worse.
Here's the frame that makes everything else make sense, and it came straight from a conversation with the crews who crawl under these houses. Asked plainly whether the crawl space is the cause and the sagging floor is the symptom, the answer was immediate: "Yes. 100%."
A sagging floor is the symptom. The cause sits underneath: a support post or pier that gave out, a beam or joist span that was always too long, or a footing outside that moved. Which one it is decides whether the floor can be brought back toward level or only held steady at the height it sits today.
Why that distinction is worth your time
Because it decides what actually gets fixed. Sanding a dip, shimming a threshold or laying new flooring over a low spot treats the part you can see and none of the part that moved.
The crews watch this happen in a predictable order. Homeowners pour a self-leveling compound, then put the granite, the cabinets and the tile on top of it, and the floor looks perfect for a while. In their words: "then that will start to move because it was just, nothing was done underneath."
The floor goes wherever its supports go. Find the supports first.
Three different problems, one identical symptom
From upstairs these look the same. Underneath they are not remotely the same, and only one of the three is a foundation problem.
A support under the floor gave out
The most common one by a wide margin. A post, a brick or block pier, or a beam under that stretch of floor failed, and the joists came down with it. The owner's own list of what they find: "We get into the basement, and we realize there's water. It caused those pilings to drop, or they rusted out, or they rotted out, or the brick crumbled because they got so old."
There's a slower version of the same thing. When a house was built, the block piers down the middle of the crawl space often didn't land at exactly the right height, so the builder made up the difference with wood shims at the top. Those shims compress. "The wood shims compress, and we have a system where we'll go in, take that out." Decades of that reads upstairs as a floor that slowly went soft in the middle.
The ground under a footing moved
Here the floor is a passenger. A perimeter footing sank and everything above it rode down with it. This one rarely travels alone. You'll usually find cracks in the brick outside, a door that quit latching, and a whole side of the house reading low rather than a single room.
You'll read everywhere, including in Google's own summary of this exact question, that Georgia soil puffs up when it's wet and shrinks back when it's dry and drags footings around. The soil data doesn't support that. USDA-NRCS rates the red clay under most of metro Atlanta low for shrink and swell. It's dense, not expansive. What actually moves a footing here is water with nowhere to go, uncompacted fill, and erosion under an edge. If that's what you're dealing with, the signs show up above ground first, and the signs of a foundation problem is the better read.
The floor was never level to begin with
This is the one almost nobody writes about, and it's more common than you'd think. Describing a house they'd walked that same morning: "the floor is out of level, not due to the foundation sinking or anything else." Nothing failed. Nothing sank. It was framed out of level in the first place and has simply stayed that way while you lived on it.
There's a related version where the framing is fine but somebody put a load where the floor wasn't built to take one. A load-bearing wall in a basement that landed *between* two joists instead of on top of one was doing exactly this on a job they described. The wall was about four feet long, and the sag it created was ten feet across: "Everything pulled toward the area, because of that wall sitting in between the floor joists."
Are all sagging floors a crawl space problem?
Worth saying out loud, because it changes where you look. "Not all sagging floors are over a crawl space. It may be a legit, normal basement that you put your cars in, and that span from those 4-inch metal poles that you see are too far apart, and that main beam is sagging because it just was too far."
The same failure, in other words, in a completely different-looking place. And the summary of it: "It's always usually because of the span issue, or the floor's not thick enough to hold the weight, whether it's on the crawl space or a regular 8-foot basement wall."
So before you assume the answer is under a crawl space hatch, find out what's actually below the room that dips. It might be a basement, a garage, or another room entirely.
Why a house that was fine for 30 years sags now
Nothing under your floor got weaker overnight. The load on top of it went up.
Kitchens are the clearest example, and they're where the crews see most of it. "They see a lot of damage happening around stairways, kitchens, that's where we see a lot of it, because of the excess weight that's been added to it, including the kitchens. These homes ain't been built to take tile, marble, kitchen islands that's been added, these new countertops, new cabinets. These homes 30 years ago wasn't built for that."
The framing detail behind that: code now asks for a 2x10 joist within a 12-foot span, and plenty of older metro Atlanta houses were framed with 2x8s. Those 2x8s were adequate for carpet, plywood and a small kitchen. They were not sized for a stone island, a tile floor and a wall of new cabinets. The joists didn't fail. The job description changed.
That's also why a sag often appears right after a remodel. The remodel didn't break the floor. It revealed what the floor could carry.
How much of it can realistically come back
This is the question homeowners actually want answered, and it deserves a straight response rather than a sales one.
A floor can usually be brought back *toward* level. Promising a perfectly flat result is a different claim, and it isn't one Anglin's makes. How much correction is possible depends on the house and, more than anything, on what the finishes above it can take. A deliberate partial lift of a quarter inch to a half inch is often the sensible answer: enough to split the difference between where the floor is and where level would be, without popping a backsplash or cracking a countertop.
A full lift is sometimes the right call and sometimes not. One recent job took a floor over a garage back a full inch with a beam and a post. Other floors get held exactly where they are on purpose. Two things drive that decision. First, the finishes: the more stone, tile and rigid cabinetry sitting on a floor, the less of the sag can come out of it safely. Second, the one-shot nature of the work: "You got one shot to do it, one shot to get it right." A floor lifted, dropped and lifted again is a floor that cracks.
And there is a floor type that simply can't be lifted. Houses framed with floor trusses instead of joists can't be raised without breaking them, and the honest answer in that case is that it's something to live with. You'd rather hear that from an estimator than find it out after a deposit.
Which of those three outcomes fits your house, and what it costs, is laid out on the sagging and uneven floor repair page. What gets installed underneath is on the crawl space repair page.
What a good inspection looks like
A customer describing a 1924 house:
"Prompt, courteous and professional. The team showed me the root cause of my sagging kitchen floor in our 1924 house, took measurements and quickly made and added key supports that will last the lifetime of the house. Expert and affordable, I couldn't be more pleased with their work."
Skip Maryland, 5 stars
Note the order in that: root cause first, measurements second, supports third. That's the sequence, and it's the same one you can start yourself this afternoon.
What you can check before anyone comes out
None of this costs anything and all of it makes the visit shorter.
- Find the low point, not just the slope. Walk the room and note where it bottoms out. One clear low spot usually means one failed support. A steady tilt across a whole side of the house usually means something else.
- Find out what's under that exact spot. Crawl space, basement, garage, or another room. That single answer narrows the cause more than anything else you can do.
- Look at the bottoms of the posts, not the tops. From the crawl space door or the basement, the failures show up at the base: wood sitting straight on dirt, rust at the foot of a metal post, a pier with mortar crumbling out of it. What's carrying the floor down there, and what replaces a post once it has failed, is its own subject: crawl space support posts. If there's standing water down there, that gets dealt with by a drainage company first. Structural repairs don't go into a wet crawl space.
- Write down when it started and what changed. A new tile floor, a stone island, a wall taken out, a bathroom added upstairs. The timeline is often the whole diagnosis.
- See whether anything else in the house agrees with it. Doors, windows and cracks that all point the same direction mean something different than a dip in one room. That's covered in signs of foundation problems.
Frequently asked questions about sagging floors
Is a sagging floor dangerous?
Almost never in the sense people mean. Residential floors don't drop out from under anyone, and a slope you've been walking on for years is not a countdown. What a sag does do is get gradually worse and get more expensive to correct, and it can tell you something is failing underneath that's also holding up a wall. It's worth understanding this year, not worth panicking about tonight.
Why did my floor start sagging all of a sudden?
Usually it didn't, you just noticed it suddenly. Something made it visible: a new appliance that won't sit flat, furniture moved, a rug taken up, or a remodel that put a level surface next to an unlevel one. The other real possibility is that the load changed. A heavy new floor covering, a stone island or a wall removed upstairs can turn a floor that was quietly coping into one that's visibly dropping.
Are uneven floors normal in an older house?
Some unevenness is genuinely normal and plenty of it was built in. Older houses were framed to looser tolerances, settled into their footings early on, and were never meant to read flat under a four-foot level. What isn't normal is a floor that keeps changing, a low spot that has a soft or bouncy feel to it, or a slope that's showing up in the doors and the drywall at the same time.
Can heavy furniture or a large aquarium make a floor sag?
It can contribute, though it's rarely the whole story on its own. A heavy load concentrated in one place, a big tank, a gun safe, a piano, adds to whatever the joists underneath were already carrying, and if that span was marginal to start with, the extra weight finds the weakness. Permanent additions like tile, stone countertops and a kitchen island matter far more than anything you can push across the room.
How do I tell whether the sag is getting worse?
Give it a reference point and a date. Set a level or a long straightedge across the low spot, measure the gap under it at the deepest point, and write the measurement and the date somewhere you'll find again. Check the same spot in three months. A number that hasn't changed tells you a lot, and so does one that has.
Who do I call about a sagging floor?
A structural repair company, not a flooring contractor, at least for the diagnosis. A flooring company can make a floor look level and a floor company is the right call for finish work afterward, but neither one is going underneath to find out what dropped. Start with whoever will measure the floor upstairs and then get under the house, and be wary of any answer that skips the second half.
Find out what's under that low spot
You shouldn't have to guess at this from your kitchen, and you shouldn't have to pay to find out. Someone can measure the floor, get underneath it, and tell you plainly whether a support failed, a footing moved, or the floor was simply built that way.
Anglin's has been doing this in metro Atlanta since 1930.
Call 770-422-2924 for a free look.