Updated November 2, 2026
Key takeaways
- Most sagging floor jobs fall between $1,000 and $10,000.
- Sistering runs about $100–$400 per joist.
- Steel support jacks run $300–$1,000 each.
- A low crawl space adds labor, sometimes more than the materials.
The typical sagging floor repair cost runs $1,000–$10,000. That's a big spread because it covers everything from one tired joist near the tub to a new beam across the house.
So how much does it cost to fix a sagging floor in your home? That depends on what's causing it. A cracked joist and a sunken post feel the same underfoot, but they're very different jobs.
Here's what we'd want to know before giving you a number. Is it one spot or a whole section? Is the wood sound, or does a screwdriver sink in? Can a person get under there easily? Those three answers usually explain most of the difference between a small bill and a big one.
Sagging floor repair cost by fix
Sagging floor repair cost depends on which fix you need. How much does sistering joists cost? Around $100–$400 per joist. Here's how the common jobs compare:
| Fix | Typical range |
|---|---|
| Sister one joist | $100–$400 |
| Sister several joists | $400–$4,000 |
| New support beam and jacks | $1,500–$7,000 |
| Joist and subfloor replacement | $1,000–$10,000 |
These are typical ranges, not a quote. Your exact price depends on what we find at the inspection.
What changes the cost to fix a sagging floor
The cost to fix sagging floor problems depends mostly on how hard it is to reach them, and crawl space height is the big one. A crew working in 4 feet of clearance moves far faster than one on its stomach in 18 inches. Here's what else moves it:
- Rot. Rotted wood has to come out, and that takes longer than reinforcing.
- Termites. Get the pest treatment and paperwork done first.
- Plumbing in the way. Drains and supply lines often run right through the sag.
- How far it spreads. One joist is a morning, and ten is a project.
Our page on fixing a floor that dips explains each repair. If the cause turns out to be below the joists, you may be looking at crawl space repair instead.
Timing also plays a part. A floor with a slight dip and sound wood can often wait while you plan for it. A floor with soft spots near a tub or a heavy appliance shouldn't wait as long, since water damage spreads and the repair only gets bigger. If you're not sure which you've got, have the wood tested before you decide.
It also helps to look at the price of doing nothing. New flooring won't last on a moving subfloor, so if you're planning a kitchen or bath remodel, fix what's underneath first. That's far cheaper than tearing out new tile a year later.
Cost to fix sagging floor joists vs. replacing them
The cost to fix sagging floor joists by sistering is almost always lower than replacing them, so we start there if the wood is sound. Sistering leaves the old joist in place and adds strength next to it.
Replacement makes sense when the joist is soft, split or eaten by termites. It costs more because the floor above has to be supported first, then the old wood comes out and new lumber goes in. Either way, you've got to fix the moisture or sagging floors repair cost comes around again.
Can you save by doing it yourself?
Yes, on materials, but the savings are smaller than they look. A sister joist, bolts and a jack don't cost much, and a handy person can do one accessible joist. The risks are real, though: lifting too fast, hitting a pipe or missing the actual cause.
We wouldn't try to change beams or jack up a floor under a load-bearing wall on your own. A mistake there can cost far more than the repair. Want a ballpark before you decide? Try the repair cost estimate tool.
Sagging floor cost questions
How much floor sag is acceptable?
A common rule of thumb is span divided by 360, so about 1/2 inch across a 15-foot joist. Older homes often exceed that without being dangerous. What matters most is whether it's changing. A sag that's growing needs attention, even when it's still under the number.
Will insurance pay for sagging floors?
Usually not. Insurers treat rot, wear and poor framing as maintenance. Sudden damage from a covered event, like a burst pipe, can be different, though the policy decides that. Call your agent and get photos before anything is repaired, so you've got a record of the damage.
Does fixing a sagging floor require permits?
Sometimes. Replacing beams or other structural parts often needs a permit, while sistering a few joists may not, depending on your city. Check with your local building department. We handle permits where they're required, and we'll list that in your estimate if it applies.
How long does the repair take?
Most jobs take 1–3 days. Sistering a few joists can be done in a day, while adding a beam with new jacks and footings takes longer. Low crawl spaces and plumbing in the way add time, and we'll tell you what to expect before we start.
How much can you jack up a sagging floor at once?
Only a little, usually about 1/8 inch at a time, with a pause between lifts. Old wood and finishes need time to adjust. Lifting fast can crack plaster, pop tile and break pipes. A floor that took decades to sag shouldn't come back up in one afternoon.
How much does it cost to repair sagging floor joists?
Sistering runs about $100 to $400 per joist, so a small area might total under $2,000. Larger jobs with a new beam and jacks run higher. Replacing rotted joists and subfloor costs more than sistering because the old wood has to come out first.
Is sagging floor repair worth the cost?
Usually, because sagging rarely stops by itself and the damage spreads. Fixing one joist now costs far less than replacing a section of subfloor later. It's also a common item on a buyer's inspection. If the sag is small and stable, tracking it for a while can be a fair choice.
Run into a term you don't know? This may help: foundation terms explained.