Carpentry and Woodworking - sagging floor

Hello
I remember years ago my father-in-law very, very slowly jacking up a sagging floor. I live in a townhouse and the middle floor, or the one above the cellar, has a sag in one bath that also affects a small area outside the bath.
What type of 'jack' could I use to turn little by little each day until the problem is corrected. What would I use to hold this area from sagging again. I understand there will be some cracking etc as the sag is at least reduced.
Thank you for your suggestions.
Peter

A very heavy duty car jack will work, along with a 4x4 piece of wood. The metal colums are called lolly columns and can be purchased at Home Depot. You will find that it will not only take a chance of cracking the grout on any tile flooring, it will also crack drywall and throw your bed/bath doors out of adjustment.

Be prepared for the snowball effect.

You also have to make sure the concrete can withstand that much pressure without cracking.

Not really a DIY'er project.

I hear you. Mike. Maybe I'll let the next homeowner take care of it.
Thanx
Pete

Peterr -

This project could get a little tricky since it's a "middle" floor. If you remember your high school science, there was a "law" that said "For every action, there is an equal and opposite reaction."

This is why jacking a "middle" floor requires that you provide some kind of support under the floor where you set up your jack. Otherwise, you may move the floor down instead of moving the ceiling up. If it's a concrete floor, you may break it.

Ideally, a lally column should be on a good footing (probably 2'x2'x2' deep) which should be poured and allowed to cure. When it's cured, you can use it as a base for your jack, then put in your new lally column.

The amount of jacking you'll do is a judgement call. Sometimes you can get rid of all of the sag but other times you may have to settle for only part of it. In some situations, you don't get rid of any of the sag and the new column just stabilizes things so the sag doesn't get worse.

Like Sawustguy says, this really isn't a DIY project. It isn't really difficult, but it does take some experience and the right equipment. Personally, I would never try this with an automobile jack - they just don't have the lifting capacity.

Thanx, Dave. I'll hope this sag does not get any worse.
Pete

Peterr -

Hoping for the best may not be a real good plan. :eek:

Is the floor sag getting worse or has it been there for a long time? If this is a new (or worsening) problem, you really should look into some kind of fix - even if it's a temporary support to stop it from getting worse. A lot of those potential "next owners" may just walk away from your place if you just let it go. :(

I only say that you could use a heavy duty car jack, because that's what they used in my moms house and it worked just fine.

I'm sure there are better jacks to use, but for the people who did the floor in our house, it worked. We used a 3" thick x 12" high x 25 ft long paralam beam.

The OP mentions the sag is in a bathroom. The problem could be the result of damage to structural members done by water leakage over time. I would check for that before I started jacking up the floor.

I've seen it done with car jacks, Mike, but it scared the bejesus out of me. All I could think about was that the jack was made for lifting (part of) a car..........not (part of) a house. :eek:

Once I raised the center of a two story house by about 2". On the second day of raising it, the owners daughter told me that she couldn't handle the "floating" sensation she was getting in her second story bedroom. :)

We used three 20 ton bottle jacks and 6-7 screw jacks for that one. :D

In addition to some good advice already served, remember that you can't focus on a single jacking point. The lam beam is a good idea. You need to spread the lift out several feet. More than one jack is a good idea also. Preferably four to six jacks.

Hello
Thank you for all the advice.
I'm going to have a contractor look at it and get some other professional opinions. It is woth looking into but with caution; the next possible owners could be a problem as is mentioned.
Pete