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Re: garage settlement

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Andrew,
 
Thanks for the additional thoughts.  The vibration issue makes more sense when you factor in that the 36" deep garage wall is probably on some amount of fill on a slope - it drops off at a 3:1 for about 100ft with much of that slope being fill and septic mound.  Not to mention that I have been watching the cracks and they increased in size quite a bit during the paving episode.  This is otherwise an area of PA that does not see a lot of settlement except for in the disturbed layer, if there is one.  I can't rule out a deeper issue - except that I would probably have problems in other areas as well, which I don't.  This problem is well isolated to one area.
 
My bigger concern about the soils is how deep the piers would have to go.  $$ if its an extra 50ft at $15/ft.
 
The contractor is really selling his product be overestimating the quantity of anchors.  They propose 8 where 4-5 will do.  I would not accept their advise based on their rules of thumb.  But that's another matter.
 
Cracking of finishes and of the foundation wall is very consistent with dropping and rotating about the deeper main foundation footing.
 
Thanks again!  Much appreciated!
 
Jim


From: Andrew Kester <akester(--nospam--at)cfl.rr.com>
To: seaint(--nospam--at)seaint.org
Sent: Friday, May 1, 2009 10:41:22 AM
Subject: re: garage settlement

Jim,
Couple thoughts. Why does the contractor suggest you NOT get a geotech study? But he wants you to use his product to fix a problem which you are not completely sure about? Does he fully understand the soil issues causing the settlement? You know what the contractor's motive is, to sell his services....
 
Without a full geotechnical report, you could call a local geotech, you probably know one, and negotiate some very limited borings and penetrations along the footing. Find out what is really going on with the soil before you determine the solution. Once you determine is it a shallow or deep soil issue, you can compare different repair methods. I would compare the cost of soil grouting, that is a popular method in FL but maybe that is because we have Sandy soil.
 
I also highly doubt the paving of your driveway caused significant vibrations to cause any damage or settlement, particularly to a 20 year old structure. I just did a bit of research for a recent forensic job regarding road construction and the effects on a nearby structure.
 
Do you have any other details of what is going on with the building? Cracking, separation of finishes, other damage?
 
My $0.02.
 
Andrew Kester, P.E.
Orlando, FL