Leveling an Old House

[phelan]

We just bought a house built in 1941. From what I've been able to see so far the home was built on a concrete block foundation without any center supports. The building is about 30' X 50' single story and the floor seems to tilt in every possible direction. All of the support joists are 2X6, a few are paired together so as to be 4X6. Over the years several attemps have been made at leveling as the crawl is littered with old bricks and other flotsum. The crawl space is very shallow, in some places 10" or less. The only tool I own to tackle this with is a 20ton jack and some I-Beam. First of all will the jack do the job? And second, do I start at the lowest point and lift in phases?

[Bob Cougham]

This can be a pretty major job or a medium job depending on a number of factors. It can also have some pretty big consequences. Cracked plaster, doors that don't close, and the whole crushing yourself factor.

The first thing you need to do is draw a fairly accurate diagram of your foundation and joists. Outside dimensions, size and span of joists, size and span of beams, if any etc. I would dig quick test pit outside the house and figure out the depth and size of your footing. Take pictures then bury it again so you don't underpin the thing.

The next thing to do is to figure out exactly how it is listing. One way to do this is to get in the crawlspace and check for level at a bunch of points. A miserable couple of hours with a helper, your sketch and a water level oought to do it. Check the foundation all the way around and the joists/beams. Record everything. Depending on your construction, you may be able to check the foundation from the outside. You can try to check the floors from above, but there can be a lot of hidden factors that can skew your results. But you should cross/check what your acertain from below on top to make sure there hasn't been some sort of repair attempted (shimming, added subfloor etc.)
Now you know where your leaning, you will probably find some definite trends. Look for explanations. Inadequate footing, undersized joists, to large of span, crooked beams. If there is excessive settling in one area water is usually your culprit. Look for bad plumbing, for instance if seen washers that drain into the crawlspace! Also, dirt that slopes toward the house, broken or missing downspouts, no gutters.
Obviously if you don't fix the cause then any work you do will be wasted.

Tough to give advice on the actual leveling until I know the cause. The rule of thumb is to go extremly slowly when raising the house. usually people use screw jacks and will raise the thing a very small amount, then let it acclimate for a week, repeat....