mgibbs21

i recently inherited an older house and in the kitchen i noticed the floor sagged. quite a bit too. its about a 3- 3 1/2" difference. now when i went into the crawl space to find the cause i discover that at some point in time there was a small addition added onto the kitchen (3 1/2' x 12'). now when this addition was put on they removed about 1 1/2' worth of stone from the stone foundation to run piping and this is where the sag all runs too. now they did add a new cement block foundation on the addition but right where the rocks are missing in the old foundation and where the new and old floors come together it sags.. i was thinking to fix the problem i would dig 3 or 4 4' holes and make footers with sonotubes about 1' in from the the old girder. jack up the floor to level and then install a new 4 x 6 or 6 x 6 girder with 4 x 6 posts going from the girder to the new footings. my question i guess is would this be sufficient or would i have to replace the old foundation? its a tight crawl space. its about 18 inches from the floor joist to the ground. this is a rough drawing i did on paint just to give an idea of what I'm talking about.(not to scale)

joecaption

I'm not there so bare with me.
There would be no way to even fill the tubes once there in there.
And 4" would be to small anyway. There would be no reinforced footing for them to sit on.
A 4 X 6 would not have nearly the strenght as ganged up 2 X 6's or 8's when it's top loaded. And would be much lighter to work with.
Any chance of a picture facing the area where the stone is missing?
Is there a supporting wall above where the stone is missing?
What condition is the floor above this area?

mgibbs21

ok i was mistaken on the first post on one thing, the hole in the foundation wall is about 3' long. at the bottom of the 4' hole i was going to dig i was going to pour a 1' x 1' x 2' deep slab then the sonotube on top of that. Id be able to fill it but it wouldnt be easy. i do like the ganged up 2 x 6' idea. there is no supporting wall above it anymore, they removed it when they did the add on. the roof rafters do go to the newer outside wall. the floor has a very noticeable sag and it hits its lowest point right above the hole in the foundation

joecaption

Hard to make heads or tails out of that mess.
What is that 2 X laying horizontal?
What is the area that looks like 1 X 4"s in a line?
Why are there two new looking 2 X 4's sitting vertical?

isola96

joes correct on no space to fill or even put tubes in there.
The new 2x4s looks like the attempt to raise it or keep it from not sinking anymore?... Maybe I could be really wrong just speculating But if not that is not the way to do it.

It seems like the didn't foot the bottom of the new addition so it relaying on the existing

Can I ask if there was a permit for the addition and if so was it inspected and if it was inspected did the inspector Check in that area?

isola96

Joe do they make post jack small enough to maybe jack up the in that area to then put some lolly columns in? You will have to foot the bottom or the jacks will just sink in the ground maybe level it and lay 8x8?

mgibbs21

the picture is from under the old part looking toward the addition. the newer 2 x 4s are just a brace the old owner put in to cover a 6" x 4" hole the the floor. the 2 x laying horizontal is the sill plate. as far as a permit i havent a clue. the guy the house used to belong to said the addition was put on when he was a kid, that was about 45 yrs ago. most of the stone foundation is still there, i didnt know if i could jack it up to level then just replace the missing stone in the foundation. the stones are still in the crawl space so it would be easy to do.
thank you for the comments

nealtw

I would dig out an area for a footing as close to the wall as I could with out damaging what is left of the foundation, my dig out would be for a footing 18"x 60" and 8" deep centered on the sag. Hang a peice of dry 6x6 timber from the joists over the footing. With a 20 ton jack in the center, jack it up. This may take a long time to lift it up, 1/8" per week. When it is up, put a 6x6 post at each end remove the jack and repace it with a third post.
I know, your not supposed to use a post but after it is blocked up, it is not doing much but will add stibility for the jack.
The footing will need a grid of rebar in it.