foundation cracking and settling

huangyhg

foundation cracking and settling
my was built in 1948 in tacoma, washington.  when i purchased it i had to tear down an existing outdoor deck and stairs which uncovered a crack in the foundation that starts at a doorway and extends down to the footing.  the crack is about 3/8" wide, and the adjacent corner of the house has settled to the point where the doors upstairs won't close, the floors are unlevel, etc. is it possible to re-level the upstairs by jacking up the floor joists, or should the foundation be jacked up?  if the foundation is jacked up should the footing be extended to prevent further settling?  does anyone have any reference books on this subject?
i would recommend first determining why the foundation is settling at that corner.  then fix that problem.  anything other fix would most likely be temporary until the foundation settles again.
you have then -it seems- corner differential settlement (that the other part be the one that has more moved seems more unlikely, yet it could still be the case, a i would think very rare one). maybe different strength in the soils, clay yielding softly in the corner, loss of material, slope washing etc. look for the cause, true. also i would say that it seems the foundation beam seems be scarcely reinforced, being the loads from a house. that's why the bracketing way of dimensioning foundations, and continuity in them is a good approach to foundations, especially if in buildings of moderate size: a stout beam could have even stood in cantilever the failure under the corner. that's too much exacting, but even without going as hard, it would have helped to diminish the unforeseen foundation movements' effects.
agreed, ishvaaag.  this is a classic example of why you should reinforce residential foundation walls.
tony3 (visitor)10 dec 01 2:59
look into atlas piers....they have a system for fixing what you are talking about.  they use a screwed in soil anchor as a foundation/support to jack up the settling foundation and permanently support it.  also, their guys whom i have dealt with can tell if there is some other problem.
have fun
tony
thanks!  i agree that the reason for the settling needs to be isolated.  i will look into atlas piers.  have a great day!
you mention you can see a 3/8-inch wide crack in the foundation.  is it wider at the top or the bottom?  is there any difference in elevation (faulting) between the "right" side and the "left" side as you are looking at the crack?
answering these questions will help to lead you to a cause of the settlement.  you will also need to know some basic info about the subsurface conditions (i.e., clays, sands, silts, residual soils, etc.).
to answer your original question, yes you can lift and level the foundation by several means.  atlas piers and other similar foundation remedies can work, assuming you can get access and can penetrate to a competent soil.  pressure grouting can also work, keeping in mind that if the settlement is due to consolidation of underlying clays or silts, then any weight you add to the foundation can contribute to additional settlement.
ron
have a hydrostatic test performed by a plumber (insurance usually covers)to determine if your wastewater pipes under your foundation are leaking.  if water is getting under your slab it will cause the soil to expand and crack your slab.  
i have seen a number of failures of this type.  without seeing yor situation, i cannot diagnose the cause, but there are a number of possibilities.  in addition to the possible soil problems mentioned in the previous posts, a plumbing leak, as drose977 mentioned, is also a possibility.  i have seen water service leaks wash away the soil beneath a footing, causing the corner of a foundation wall to crack at both walls and settle.  i saw a similar failure due to the breakage of a storm sewer pipe that ran alongside a foundation at a distance of about five feet.  everything looked fine until bam! the foundation cracked and settled. another, odder, failure-but one borne out by soil borings- was during a dry spell, ands a large tree near the foundation was taking moisture from the soil that wasn't being replaced by rain.  the soil under a foundation corner dried and contracted whereas the soil under most of the foundation stayed moist.  again, foundation cracking and failure.
atlas-type piers or other permanent posts/jacks can usually be advanced to stable soil, allowing adequate underpinning of the foundation.  likewise, jacking the joists should work as well.  it would be well worth your while to find a contractor that specializes in such work.  i have seen inexperienced contractors attempt these jobs with disastrous results.  good luck!