sinking slab- s florida home

huangyhg

sinking slab- s florida home
realtor got a 30,000$ estimate to shore up an approximate 10" round portion of slab that has sunk very slowly over the course of 23 yrs. now there is a slant in the room and a portion of wall has separated from a vaulted ceiling as well as a gashing in the upper part of same ceiling.  can this be repaired insofar as the sinking will not start up again?  is it really that costly?  cosmetically, it is not that big a deal, unless it continues.  is this house worth buying at a greatly reduced price or will the problem always exist?  thanks in advance.
find a job or post a job opening
hi there. i am a structural engineer who lives and practices in florida. i am familiar with situations like yours.
before you do any repair work, please hire a competent structural engineer to evaluate the settlement and its causes. this is a serious issue in my opinion; to simply rely on contractors to solve your problem may not be your best choice. the engineer may retain a geotechnical engineer to take boring samples of the soil layer beneath your slab/house. ground penetrating radar may be useful in finding out if any voids exist under the slab.
once the source or reason for settling is discovered, corrective action can be developed by your engineer. there are many techniques available to stop the settlement and to control/prevent future settlement. some of these techniques are:
1. use of needle type piles
2. under pinning using helical type anchors
3. injecting cement/rout under the slab
4. injecting urethane type material that will expand, fill voids and expel any present water from the voids under the slab (one commercially available material that i used in the past to correct apron to navy hangar is uretek; this is a link to their web site
failure to hire a competent geotechnical engineer to study your problem is absolutely foolish.  in fact, you should hire the geotechnical engineer first - after all, the underlying problem has to do with the support of the structure, not the structure itself.  you will need to hire a structural engineer, but his/her services don't really come into play until the problem has been defined and you are looking at repair methods.  and that won't happen until you begin developing your tender offer.
i suggest that you search eng-tips using the key words: subsidence, sinkhole, sink hole, attorney, insurance.  there are a number of good threads on this issue - you should read them before you buy this property.
i'm not licensed to practice engineering in florida.  but i know enough to know that sinkholes can develop slowly, then "grow" quickly.  don't let the 23 years of slow settlement fool you...
keep in mind that your insurance policy - if this property is even insurable - may exclude coverage for this problem.  that is a big deal.
i just completed a repair (in florida) with the same problem as you indicated.   follow lutfi's guidance (he got my vote).  i hired the geotechnical first got the report, then hired a structural pe that installed helical piers.
you may not be able to completely level the room, only stablize it (due to wall cracking , ect).  after you stablize the  structure, try fiberglass tape to repair the plaster.
goodluck
focht3 is right.  i am a structural engineer living in florida also, and would definately recommend hiring a good geotechnical engineer first.  with a solution in mind, as well as proper evaluation of the problem, a structural engineer can then evaluate the structure itself.