How do you handle sagging floors? Do you fix them or leave them?

We fix them. A sagging floor means something underneath has given up, usually a tired support post, a rotted beam, or a footing that settled. We level the floor back to where it belongs and put real support under it, with floor support work starting around $1,300 to $2,500. We almost never tell a homeowner to just leave it, because a sag that moves keeps moving.

The first floor of a house rides on beams. Those beams rest on posts that carry the load down to a footing in the ground. Over time one of those parts fails. A wood post on a basement slab can soak up moisture and rot at the bottom. An old beam can split or sag between supports. A footing poured too small can settle into the soil. When that happens, the floor above dips, and you feel it as a slope, a bounce, or a door that will not latch right.

So we look under the floor first. Free inspection, free estimate, quote inside 24 hours. We find the real cause, because the fix depends on it.

How we fix a sagging floor

For most sagging floors, the answer is adjustable steel support posts, what the trade calls lally columns, set on proper footings under the beam. We use a low-pressure approach over days, not one hard crank in an afternoon. Rushing a floor back up cracks drywall and tile, while going slow lets the wood relax toward level. Floor support and post work starts around $1,300 to $2,500 with a 10-year warranty.

If the post is fine but the beam is shot, that is a different job. Sill and beam replacement runs around $7,000 to $40,000. We carry the load on temporary supports, swap the rotted wood for new, then set permanent posts under it.

When the trouble is in the ground, when a footing has settled and the whole corner is dropping, posts alone will not hold. That calls for helical piers, steel shafts driven down past the disturbed backfill to firm soil. We self-perform helical installs in-house, no outside crew. Helical piers start around $2,700 per pier for the first three, then $2,200 per pier after that, with a 25-year engineered warranty.

You may not need all of that. Some floors bounce because a span is a little long for the joists, and a single post in the right spot solves it. We will tell you that. We are not going to sell you piers for a bouncy floor that wants one column.

Why a NH floor sags in the first place

A lot of sagging comes back to water and soil. When your house was built, the dirt dug out for the foundation got packed back in around it. That disturbed backfill drains slowly and holds water, so the ground near your foundation stays damp. Damp wood rots and wet soil settles. New England frost heave adds the rest: frozen ground pushes, then thaws and drops, and that cycle works on footings and posts year after year.

If your basement or crawl space stays wet, the floor problem keeps coming back no matter how well we shim it. A post we replace will rot again in standing water. That is why we often pair a floor fix with drying out the space underneath, whether that is basement waterproofing or crawl space encapsulation. According to the U.S. Department of Energy, up to about a third of a home’s heat loss can come from an uninsulated foundation or crawl space, so drying and sealing it pays off twice. A sagging floor over a wet crawl is one job to us, handled in the same project.

What it costs and what we do not price sight unseen

Floor support starts around $1,300 to $2,500. Sill and beam replacement around $7,000 to $40,000. Helical piers around $2,700 per pier for the first three, then $2,200 per pier after that. The real number depends on how many supports, how far the floor has dropped, and what we find when we open things up.

Some jobs we will not price over the phone. A full foundation-wall rebuild or steel I-beams, those we price after we see it. We are not going to throw a number at a structural problem we have not stood under. If your house needs a brand new foundation, that is new construction, and we do repair, not new builds.

Financing runs through Hearth, subject to approval. We make nothing on it. It is there so a structural fix does not have to wait.

Talk to us about your floor

Call us at 603-610-1770 or book your free inspection. We will get under the floor, find the cause, and give you a straight number inside 24 hours. Licensed and insured, BBB A+ accredited, trusted by 5,000+ homeowners across New Hampshire, Maine, and Massachusetts.

See more on structural and foundation repair, helical piers, sill replacement, supplemental support, and the 603 guarantee.

Related questions

Can a sagging floor be dangerous? A small dip is usually a comfort and cosmetic issue. But a floor that keeps moving, with new cracks or doors that suddenly stick, means the support is still failing. That one needs a look soon. We do free inspections, so there is no cost to find out which kind you have.

Should I just live with a slightly sloped floor? If it is old, stable, and not getting worse, you can. We will tell you when that is the case. The trouble is knowing it is truly stable, which is what the inspection is for. A sag that is still moving will not fix itself.

Will jacking up the floor crack my walls? It can if it is done too fast. We lift slowly over several days so the house can adjust. That is the whole reason we do not just crank a post up in one visit.

Do you fix the wet crawl space causing the sag too? Yes. If standing water rotted your posts or beam, we can dry the space with crawl space services in the same project so the new wood does not rot again.