Thanks, Kudzu. This is the basement ceiling directly under the sinking boards. What should I be looking for?

Here's how to send Joseph an email. Find a post he made,click on his name to bring up his profile page, click "message" in upper right of profile page.

Hit the flooring down with a tapping block and put a nail or two into it. Save yourself a couple of hundred dollars.

Thanks, G&S Floor. But I’m not sure what you mean…the boards aren’t popping up. They bend into the floor, as if there is nothing underneath to hold them up. So wouldn’t putting a nail into a plank either do nothing (because there’s a hole underneath) or cause it to break by bending it toward the hole?

Since you have access to the bottom of the subfloor, this is a pretty easy fix.

You will need a piece of lumber, a 2x4 will work, cut exactly the width between your floor joists. Using screws, start them at angles into the ends of the 2x4 and then place, or tap with a hammer into place, the 2x4 so it spans between the floor joists under the hole. Hopefully the 2x4 is just snug enough so as you tap it up, it pushes the flooring that is drooped down, into place. If it does, drive home the screws to hold the flooring up and in place.

If not, you will need to use a jack and another 2x4 cut to span the distance from the jack, to the 2x4. You can use the jack from your car to do this. It can be a one person job, but easier if you have help to hold everything in place while another person turns the car jack. Just press the 2x4 up until it pushes the flooring board flush, and then send the screws home to lock it into place.

Based on your photo, you have plank subfloors, you need to make sure the fasteners are hitting the subfloor planks.

You can do what Travis suggest, by sucking down the board with a screw. Have someone up top, stand on the board and then someone else, fasten a 1 1/4" screw from underneath.

Here you go.

@Joseph Corlett, LLC installs counters and sinks.

But all you do is type "@" and the software will bring up any usernames with the letters you type after "@" - even ones that are not commenting in this thread.

I love the old, narrow planked wood floors. Do whatever you can to save them.

Thanks for the tips on how to fix the floor from underneath, G&S and Travis. (although I am too house-illiterate to really understand how to do it). . . If anyone lives in Twin Cities, please tell me the name of your company so I can hire you to fix my floor!

Call a flooring company. Check all the reviews, so you get a reliable person. Check with friends or family, that may have had flooring done by a flooring company.

It is a pretty easy fix any homeowner can do, but do understand my description makes it sound like rocket science. It's not, but I don't know how else to describe it.

There is nothing you can screw up because as you shove/jack the 2x4 into place, it will stop when it is level with the other flooring boards. Once it is level, just screw the 2x4 into place into the flooring joists.

I wished I lived closer as this is a 20 minute fix.

Travis, I think I understand now (after thinking for many hours about it 🤣). Is this right, what I drew in the photo? Take pieces of 2x4s the exact length of the space between the studs, push it up to hold up the floor, and screw it into the existing studs?

Travis, just as I thought I was beginning to understand…. A friend pointed out to me that the soft spot is not over the wood ceiling - it’s concrete! So previous owners renovated the house to basically double the size. Half the house is 100 yrs old, half is 20 yrs old. The sinking floor is part of the old house, which has a thick solid concrete ceiling in the basement. You can see the two different types of flooring change at the doorway. So does this dash any hope of fixing it using your method? Is the only way now to repair from above, as in replace the entire floor? (Because I already called numerous flooring companies that advertise “flooring repair” on their websites; but none will do a small job to repair the existing floor. They will only replace the whole thing.)

The only think i can think of, and i am not sure this is a good answer, is to take a 5 gallon pail and fill it with water and place it over the offending floor board. Then take a can of spray foam and insert the straw into the cracks and fill the offending gap between board and concrete with foam???

The thought is, the foam will expand and push the floorboard upwards, but the heavy bucket will keep the board flush with the rest of the floor. Then you will have to scrape the nasty residue off.

Like i said, i am not sure it is a good idea, but the only thing i can think of.

Travis, wow, that sounds even more complicated than the simple 2x4 solution I was already having trouble envisioning! So, there might be a carpenter in the area who could take on the job of fixing this. My friend said that he would remove planks from the top, fix the gaps where it’s sinking, and replace most of the boards, and stain new boards to match. Does this sound like the right solution to you? Are there any questions I should ask the carpenter (before hiring) to make sure he knows how to do it right? Anything I should watch for while he’s working? Thank you so much for helping me with this!! And for being so nice and patient explaining things since I am totally house illiterate!

Replacing the boards would be a good option, as long as its the same type of wood. Putting foam under, could be a big mess. That stuff is very hard to get off of anything, it gets stuck to, so could ruin the finish on the boards anyway. Just make sure your friend, has done this type of thing before.

Thanks, cat_ky. Don’t worry, I definitely do not have the skills to put foam into my floor, so I won’t be attempting that!

If there was ever a situation in need of a silver bullet this is it.

Klem1- a silver bullet for the werewolf? I need a magic bullet to puff up my floor! Or just a skilled person willing to take on such a small job, which seems be harder to find

The primary reason it's difficult finding someone willing to do small jobs is because most people want a few estimates and that doesn't pay well.