Support Post Footings

We bought a 1927 two house a few years ago. We added an addition onto the back of the house to make the kitchen bigger. The kitchen was originally 6' x 8' and I was told the only way we could buy the house ( by the little lady) was make the kitchen larger. Well it is and its now 13'x15. We tore off the old shngle and reshingled the house, plus we sided both the house and a three car garage. Also built a nice 8x8 deck onto the house.

I still have a problem with the upstairs bathroom to solve. Its 10'x6' with a claw tub and wall 18" wall hung sink. A wall going to have to opened up to install a new tub/shower kit and 22" vanity. The thing has a entrance door plus a 35" closet door in it. So if I put a 30" tub with shower wall in (finish depth 32" atleast) and 22" deep vanity I already bought, there is 16" of standing space between the two. So something has to give.

But before I dive into the bath, opening up a wall and refinishing them, I have to relift the main support beam in the basement 3". Here is where some advise from you will be helpful. The beam is 28' long and made up of 6-2x10 beams. I am not worried about the strength of the support beam at all. Actually it a little over kill I think, but bigger is better right?

The main supports are cast iron 5" pipes with iron flanges welded to each end. No way to adjust them other then lifting and shimming them. Might do that in a couple of places but I bought 3 adjustable support that will carry the load of the house. My biggest problem is the supports have been sinking into the ground. I know this because we tried lifting the support beam and setting it back on the supports. They gradually sunk into the thin floor. So the floor slab is way to thin for any support.

My question is, how big and deep should a pour some new footers. Our ground has a clay layer down about 30". I know this because I have had to dig post holes for the new addition and decks. With the basement much deeper then the outside ground I assume I am down under the clay base.

A freind of mine, contrator that helps me, said the footer shouldn't need to be any deeper then 18"-24" and 15"x15". He said the house has been here for 90 years and only sunk 3" with no new lifting done. I respect his advice but wanted to check with you that had done this before. I plan on using 3 supports instead of two in the basement. Is there any reason not to if I have them already? Thanks for any help

The wider the footing the less chance of sinking, I always make mine 24 X 24" wide.
One way to figure out pretty close to how much it's going to need to be lifted is with a self leveling lazer level.
It would get set up in the basement.
There so simple to use most people would not even need a manual to use it.
Another simple way is a simple piece of string streched across the whole area inside the house from outside wall to outside wall.
Once it's tight just measure the distance from the string to the floor in the middle of the room. Your also going to need a 6' level to double check inside.
One end gets set in the middle of the room there other end goes toward the wall.
3" is a big lift, things are going to be cracking an popping up stairs.
I hold not lift any more then 1/2" per day. The longer you take to lift it the better. When it's time to lift do not try and lift the whole distance by pumping just one jack. Pump one 2 pumps and move to the next one on down the line, need more then go back and start over. The goal is to try and lift the whole thing as a unit and to avoid humps
Any faster and your going to crack the sheetrock or plaster and may even break some wood.
Plan on having to go back and check all doors and all the walls and doing some min. adjustments and wall repairs.
If I was doing this I would want not less then 4, 20 ton hydrolic jacks.
I would have the jacks sitting on steel 1/2" plate about 12" X 12" on top of the piston I've made up some 4' sq. 1/2 plate with a piece of steel tubing welded together. It gets set on top of the piston, the pipe keeps the plate centered and keeps it from falling off, the plate keep the piston from just crushing a round hole in the wooden 4 X 4 used for lifting.
Once I'm all set up and there's tention againt the beam I insert 3' Long decking screws into the lifting beam through to the main house beam on all 4 sides. This will keep the lifting beam from tipping over as I'm lifting with another jack and taking weight off of it.
Once it's all lifted, if it was ine I would drill clearance through holes for 1/2" carrage bolts every 24", drill one at the top and the next one gets drilled near the bottom, on down the line, This will draw the boards together and make it far more soild. If this beam is going to wraped to hide it at some time then counter bore the holes on both sides so the nut and head of the bolt will be recessed.

Thanks for the suggestions joe.

I already tried lifting the beam last spring. That when I noticed the cement giving way under the jacks and supports. I just left the 5" cast iron supports along with the 3 new ones. I was using 2 jack but 3 sounds better for that length to me. I know things are going to crack/pop and to lift a couple of days in between. No hurry on this job as I want it done right and let the walls settle in. I still have a lot of wall work to do on the upper story and then windows to replace next fall after the lift.

What kind of concrete do you advise for the footings and how long to set up. I have a laser level, 6' lever and about enough tools to build a house after doing all the adding on and remodeling. The one thing I don't have is an automatic digger. Mine quit worker and she said she to old for this crap.

3" might sound like a lot but I would guess its even more then that. Nobody has taken care of this house or done much to it in the last 40 years. Anything thats up against the wall has to be shimmed and screwed in. I just put a 36" wide x 36" cabinet up against the one end wall. There was an 1-1/2" gap at the top of it. I am sure its going to take a month or so to lift it gradually and watch the doors and flooring.

One bad thing is I fitted new doors upstairs when we moved in, 7 of them. I can just imagine with the fitting I had to do, out of square, I might be replacing some of them.

The reason I asked about the floor above is it's much easer to work on if the floors cut out to get at it.
With only 18" to work in your limited on a lot of way to fix it.
If there's a supporting wall above the old beam and it's now bowed that bad if you try and lift just the floor joist all I can see happening is the joist will move up, the old beam stays put and it's rips the subflooring in the area of the old beam.
Without seeing it, it seamss like it would be best to bust out that old stone and lift under the beam and add new piers with footers under it.