Will fixing the floor joists fix sloping floors on both the first and second floors?

Sometimes, but not always. If your first floor sags and the second floor follows it, fixing the joists or the support under them often levels both, because the upstairs floor sits on the same frame. If the slopes run in different directions, or only the second floor tilts, the joists may not be the real cause, and the fix changes. We come look first. Free inspection, free estimate, quote within 24 hours.

Why both floors can slope from one problem

A house stacks. The second floor rests on walls that rest on the first floor, which rests on the joists, beams, and posts down in the basement or crawl space. So when the bottom frame drops, the floor above can drop with it. One low point downstairs can pull the room above out of level too.

That is the case where fixing the joists helps both floors. You correct the support down low. The whole stack settles back toward level.

But it is not a sure thing. Houses are not perfectly rigid. Years of movement, old repairs, and added weight can leave the second floor with its own separate dip. Fixing the basement joists will not touch that.

What actually causes a sloping floor

A few things, and the fix depends on which one you have.

A sagging main beam or a rotted post lets the center of the floor drop. We add or replace floor support, like a lally column or a power post under the beam. Floor support and power posts carry a 10-year warranty.

Joists themselves can rot or get cut. Plumbers and electricians sometimes notch a joist to run a pipe, and it weakens. We can sister new lumber alongside the old joist to bring it back.

The foundation can move. Frost heave in New Hampshire pushes walls inward over the winter, and disturbed backfill (the loose soil put back when the house was built) settles unevenly under the footings. When the foundation drops, the floors drop. That is when we look at deeper support like helical piers, which lift and hold the foundation. Helical piers come with a 25-year engineered warranty, and we install them in-house.

So “fix the joists” might mean sistering joists, or adding a post, or going all the way down to piers. Different problem, different fix.

What it costs

Floor support like a lally column or power post runs $1,300 to $2,500. Sistering or other beam-level structural work depends on how many joists and how much access we have. Helical piers, if the foundation is what is moving, run $2,700 per pier for the first three, then $2,200 per pier after that.

A sloping floor does not always need a big repair. If it has been the same for years and nothing is rotting, you may not need anything yet. We will tell you that. We are not going to sell you piers for a floor that just has character.

How we figure out which floor needs what

We measure. We check the joists, the beam, the posts, and the foundation. We look at whether the slope upstairs matches the slope downstairs or runs its own way. If both tilt toward the same low spot, fixing the support under the first floor usually brings both back. If the second floor has its own dip, that gets its own plan.

You get a clear answer before any work starts, and the estimate is free.

For more on the structural side, see our structural and foundation repair page, our helical piers page, and our supplemental support page. If a sill or beam is rotted, see sill replacement. Every structural fix is backed by the 603 guarantee.

For general guidance on home settlement and foundation issues, the Insurance Information Institute (iii.org) covers what is and is not typically covered, and the U.S. Department of Energy’s Building America program (basc.pnnl.gov) covers foundation and crawl space building science. [verify deep URLs]

Talk to us

Call 603-610-1770 at tel:6036101770 or book your free inspection. We serve New Hampshire, Maine, and Massachusetts. We will measure the floors, find what is moving, and tell you what each floor needs. Free inspection, free estimate, quote within 24 hours!

Related questions

Can you level a floor without tearing it up? Often, yes. A lot of slope comes from the support below, so we work from the basement or crawl space and add or fix posts and beams. You may not lose your finished floor at all. We confirm during the free inspection.

Is a sloping floor a foundation problem or just old joists? Could be either. Old joists or a tired beam cause a local dip. A moving foundation causes a wider tilt, often with wall cracks or sticking doors too. We measure both before we say.

Will fixing the basement support help my upstairs doors that stick? Sometimes. If the upstairs frame dropped with the first floor, bringing the support back to level can ease doors and gaps above. If the upstairs has its own settling, those doors need their own look.

Do you sister joists or replace them? Usually we sister, meaning we bolt sound new lumber alongside the weak joist. Full replacement is rare and only when the wood is too far gone. We pick the lighter fix when it will hold.