Messages and Online Forum Q&A

Re: Foundation Settling - Las Vegas

From: info@builderswebsource.com
Category: Foundations and Basements
Remote Name: 63.198.181.43
Date: 22 Jan 2002
Time: 08:32 PM

Comments

Without seeing your property first-hand, we can only speculate about the problem with your foundation. However, given the details in your e-mail, including your location in Las Vegas, NV and that your soil is sandy/rocky (as opposed to clay), we suspect that your problem may be due to subsidence, which has reached chronic levels in the Las Vegas Valley.

Subsidence results from extraction of groundwater at a faster rate than which it is replenished. Due to meteoric growth in Las Vegas over the past few decades, water has been extracted at 2-3 times acceptable rates. As a result, the valley floor is sinking every year. Over the past several decades, some areas have dropped several feet. Just in the past five years, some areas have dropped several inches.

Subsidence would explain all of the problems you describe, including cracking walls, slabs, foundations as well as sticking and out-of-plumb doors. Within the geotechnical community, subsidence is a well known problem in Las Vegas and has been extensively studied and mapped.

Two excellent resources on the subject include white papers from the US Geological Survey (USGS) as well as other industry proceedings:

http://geochange.er.usgs.gov/sw/impacts/hydrology/vegas_gw/

and, a more recent update,

http://www.higp.hawaii.edu/~amelung/pubs/1999_vegas/vegas.html

Unfortunately, there is no easy remedy for this problem so long as Las Vegas continues to consume more water than it can source. Foundation stabilization techniques exists but can be costly and temporary.

Generally, pier-type foundations are used in situations where the soil is unstable, but this cannot be easily retrofitted to a slab foundation.

Our guess is that this condition is not covered by your homeowner's insurance, as it is a condition that impacts almost every structure in Las Vegas. Some areas are more exposed than others, so we would recommend that you start first with the city building department and consult with a local geotechnical company if you decide to pursue a remedy.

We hope these tips help to point you in the right direction. Please keep us posted on your findings.

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