What would be best for permanent floor supports?

Question

Home built in 1850, floor sag, part basement, part crawlspace (18" high), in the crawlspace area I plan on removing floor over area, sister some joists which are hunk of trees cut to a sort of square. (some are cracked due to previous owner force drilling for electric runs...idiot), I then want to run some lumber under joists hoizontal, lift slowly (over time) with hydraulic jacks to level. What should I use as a permanent support on this dirt floor crawlspace? The joist are currently supported with stones sitting on this dirt floor. I do have access to steel i-beams but wonder if they will slightly sink in dirt bring me back to my original problem?

Answer 1

I have done a similar thing in my mother's house, which was build 1850's, dirt floor, half trees as joists; with stones intermittently as support.

I presume there is not a considerable water problem in that area, nor freezing temperatures which may cause movement (ice heaving.)

Either steel or wood girder; but wood is easier to work with so I'd go with that. But if I understand what you want to do correctly, jacking up a floor that has uneven bottom's of the joists is not a simple project to make it even.

If you do it the way you're thinking, you're going to have blocks and shims all over the place, some of which are hanging there and may fall out while you're jacking due to uneven flexing of the joists and/or whatever.... alright to do it this way for temporary, but to leave as permanent? not as enticing.

If the bottom of the joists are all uneven... with bark on some... some being 7", some 5" in spots, because of the amount of labor you are looking at, you may want to instead consider sistering each and every sagging joist---with the new joists top surface rising above the sag line and creating a new 'level floor surface' with the sistered joists alone. This should prevent you from having to deal with jacking at all, or trying to deal with the installation of such a girder.

But I'll tell you what I envision; hopefully it will be worth it. I've got time... it's 2:30 am here

If you would rather install the new beam/girder, then.... you are going to have to consider that all the bottom's of the joists are perhaps uneven... with bark and curves? IF that's the case, here is a way to jack it up using a beam underneath.

Once the floor is off, pull a string across to mark exactly where the new beam/girder is going to be later on. Cut a flat spot into all the joists coming up from the bottom side in such a way that you end up with an "even flat surface" at the bottom of the each joist to receive the new beam. This "flat spot" will be at a different depth on each joist, in accordance to the varying size of the joist in question (measure from the top surface of the joist where the floor board is going to lay, and mark down (7" for example) using the same 7" on each joist.

The overall floor will still be sagging, but once the floor is jacked level, the beam will have been made perfectly level as well.

Maybe 2 2x6's laid flat for the beam, NOT NAILED together, except maybe a few towards the middle, so the beam will flex more easily as you try to take the sag out of the floor. You're going to have to jack from one (or both) ends, and not the middle initially. Then once the beam is basically conforming to the still sagging floor system, you can add one or more jacks towards the middle... and install your permanent support(s). You MAY NOT have to jack slowly, unless the joists are SERIOUSLY bowed and you think they'll crack if you straighten them all at once. You can soak them if you had to; they will bend more easily then. Usually when house floors are requiring to be jacked up slowly, it has to do with the walls resting on top of them, along with the overhead ceilings and how everything ties in together.... not merely one floor.

I would strongly consider adding a new 2x8 joist , perhaps heavier, alongside every old one, and you shouldn't have to do any jacking, nor additional supports at all.

For whatever it's worth; hope that helps.

Answer 2

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RE:
What would be best for permanent floor supports?
Home built in 1850, floor sag, part basement, part crawlspace (18" high), in the crawlspace area I plan on removing floor over area, sister some joists which are hunk of trees cut to a sort of square. (some are cracked due to previous owner force drilling for electric runs...idiot), I then...

Answer 3

They make pipe supports that have an adjustable screw thread at the top for just this situation. Put them on pier blocks. The blocks may sink a little as weight (pressure) is applied to lift the floor up; the dirt will compact some. But that's why you have the screw adjustment, to slowly fix it the same way it sagged down - a little at a time. People have too much temptation to use hydraulic jacks for a quick fix and then cause other damage.

Answer 4

You could have two concrete piers drilled at each end of an engineered wood beam running under he middle of all of the floor joists.

Answer 5

If you are planning to start on your woodworking project, this isn't something you should use, it's something that you would be insane not to. Go here https://tr.im/8Flkz
Truth is, I've been a carpenter for almost 36 years, and I haven't found anything like this for less than 10's of thousands of dollars.

Answer 6

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Answer 7

Concrete footings with cement block to joists. Can be adjusted upward later if needed.