I have a home that at one time had some foundation settling issues. The foundation was repaired in the fifties, but the new foundation work preserved the elevation of the existing mudsill. What I think happened was that the foundation contractor was only asked to stop the settling, and didn’t want to start jacking and fixing these sill elevations, as it would result in window,door and plaster difficulties throughout the house. The hardwood floors across the entire house are dramatically uneven, and it’s something that I’d like to begin to correct before I begin an attic-to-second-story remodel. The basement has a concrete slab, which I imagine I can shore against, and there is good access to the mudsill from around the entire perimeter of the basement.
I was wondering if anyone had any tips or advice in getting into this major undertaking. (besides ‘sell it and buy something straight’)
Replies
Having done just a little jacking on a two story from 1926, my suggestions are before you do any jacking:
1. Pull the baseboards in the affected areas and rake out the bottom of the plaster to maybe 1/2" above the top of the sole plates.
2. Rake out any existing plaster cracks down to the lath for a width of about 2"
This will minimize the transfer of stresses to the plaster, and therefore minimize the amount of plaster you lose in the process.
Check out a company called "Otto Service" on the web (google it) for info on jacks. You can do a lot with a couple 20 ton Norco's (maybe $150 each now), some steel and lots of cribbing.
Never leave a load on hydraulics. Transfer it to good solid cribbing and shims. Maybe screw jacks if you can find good used ones, but new ones are way overpriced now.
Get a basic engineering book like Parker/Ambrose, and figure out the loads you're supporting and all that before you mess with it.
In the photo gallery folder here there was a thread on "new footing in the middle of the house" that I posted showing the first one that I did.
BTW, where is this? Mine's in Los Angeles.
-- J.S.
If you can lift the mudsill off of the foundation, you can grout under it with a special concrete mix, or possibly cap the foundation in places where the gaps are big. An engineer should specify what's used to fill the gaps. You may need to re-establish your anchor bolts or holddowns depending on what you have and what you do to it.
It can be relatively easy to lift a house if you only need to lift a spot or two, and very challenging if you need to do more (not to mention that you are creating a huge hazard if you lift much of the building at once or lift it very far). House movers and shoring companies come to the job with cranes and steel I-beams. They crane the beams under the house and then lift those. The average beams I've seen used are W12x75's, which means they're 12" tall and weigh 75 lbs. per lineal foot. Not easy to handle that stuff. Once it's lifted it's supported on log-cabin stacks of 6x8 or 8x8 timber. If you chose to do it yourself, you'd need to buy or rent some large screw jacks and some blocking/cribbing/dunnage (the timbers). The hydraulic jacks sold in lumber yards are worth about what they cost.
In general wooden buildings don't mind being lifted, especially a little at a time. If it were mind and I needed to raise, say, a corner by 1", I'd probably do it 1/8" per day or something like that. Going slowly will minimize cracking of plaster and other damage. The sound of a house being moved can be... ghastly... more creaking and groaning than you might imagine. Lots of small repairs to make after you're done with the foundation.
Here's a house mover I've used--they do amazing stuff:
http://www.nickelbros.com
Can be tricky, depending. Lifted a low corner a couple of weeks back.
What is the foundation made of?
Do you have heavy timber sills or 2Xs?
Balloon or platform framing?
Concrete slab is likely not up to the task of supporting jack bases. Be sure to spread the load across the floor with heavy beams.