Friday, March 03, 2006

Expansive Soil in Arizona

EXPANSIVE SOIL… So… what’s all the fuss about?

Sooo… what’s all the fuss about Expansive Soil… and what the heck is it anyway?

GREAT questions… and glad you asked…

Remember… way back in the Paleozoic Era, when Dinosaurs roamed the earth? Well… they also took up residence here in Arizona. Then… came Global Warming, the Ice Age and who knows what else… oh yes… we had that huge meteor hit the state in up-state Arizona… that couldn’t have been too helpful… Right!?!... and… don’t forget Sunset Crater one of the oldest inactive volcanoes in the state, or is it really inactive… Hummmm… I wonder?

And then… the Dinosaurs disappeared… Well… not all of them… LOL

I guess what I’m trying to share with you is just this… we Arizonians, that includes our ancestors, the Dinosaurs, have lived with all sorts of natural geologic inconveniences, and that includes expansive soil.

That said… this is a little bit of information about Expansive Soil. The soil in Arizona, in some parts of the state, has “clay like” tendencies. Specific areas of the state are prone to “clay like” tendencies, sometimes referred to as “EXPANSIVE SOIL”. It is not unusual for a home/building in Arizona to exhibit signs of settling by evidence of cracks in walls, doorways, garage floors, patio decks, drive ways, roof tie-ins and a number of additional locations in, on and around the home/building. The Registrar Of Contractors, sites any gap/crack in foundations or walls etc. That exceeds 3/16th of an inch in width is considered unacceptable and requires the attention of professionals to examine the cause of such cracks.

If a consumer purchases a home from resale inventory, the Buyer should always ask the Seller for a copy of the “Commissioners Public Report” for that subdivision. If the Buyer is purchasing a new build home, then the Builder is obligated to provide a copy of the “Commissioner’s Public Report” to the Buyer prior to the Buyer signing any contracts. In any case… no site sales associate, working for the Builder nor any real estate agent should ever issue a verbal warranty or claim as to the cause or nature or origin of these physical conditions, whether visible or hidden or whether disclosed or undisclosed.

It is the responsibility of a prospective homeowner to satisfy his or her concerns by securing an independent assessment of the home/building and the structural integrity of that home/building. A licensed, bonded and insured (PE) Professional Engineer or (PEF) Professional Engineering Firm should tender such assessments, in writing to the party or parties raising such concerns. A list of State Certified PE’s or PEF’s can be found on the Professional Registration Roster’s web site. Additional information can be obtained from the Arizona Registrar of Contractors and at the United States Department of Agriculture’s NRCS (Natural Resources Conservation Service).

¨ If the prospective homeowner has concerns about the condition of the soil under, near or around the subject property, it is suggested that the prospective homeowner contact one of the following agency locations to inquire about those conditions of concern.

Wilson, Robert W. Resource Soil Scientist Chandler Soil Survey Office 18256 E. Williams Field Rd. Suite 1 Higley, Arizona 85236
Phone: 480-988-1078 ext. 106 Fax: 480-988-1474 Voice mail: 9011-1875 e-mail:
Breckenfeld, Donald J. Resource Soil Scientist Tucson Resource Support Team 2000 E. Allen Road, Bldg. 320 Tucson, Arizona 85719-1596
Phone: 520-670-6602 ext. 242 Fax: 520-670-5123 Voice mail: 9011-1465 e-mail:
DeWall, Alfred A. Resource Soil Scientist Flagstaff Resource Support Team 1585 S. Plaza Way, Suite 120 Flagstaff, Arizona 86001-7102
Phone: 520-556-7305 ext. 229 Fax: 520-774-2780 Voice mail: 9011-1605 e-mail:

§The 1997 National Resources Inventory (NRI) is the latest in a series of inventories conducted by the U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service. It provides updated information on the status, condition, and trends of land, soil, water, and related resources on the nation's non-Federal land. The 1997 NRI is unique in that it provides a nationally consistent database that was constructed specifically to estimate 5-, 10- and 15-year trends for natural resources from 1982 to 1997. The 1992 NRI was instrumental in providing data on natural resources for the USDA publication.

In order to maintain the structural integrity of your home, long after you close escrow, proper planning and maintenance of the finish grading, pool and landscaping are the responsibility of the homeowner. Many builders recommend the homeowner take the following preventative measures;

1. Make sure that positive drainage away from your foundation is maintained
2. No landscape plantings should be placed within 2 feet of the house.
3. Landscape plantings within 10 feet of the house should be limited to low water usage plant types
4. Do not over water plants near the foundation, patios or fence walls.
5. Care should be taken when backwashing pools to ensure excess water is not allowed near the foundation, patio or fence walls.
6. Care should be taken when adding pool or landscaping improvements to ensure that any mounding or grade changes direct surface water away from the home and are in conformance with the general grading plans of the home site.
7. Regularly monitor water on your lot after rains or normal watering to ensure these maintenance items are being followed

Lori & I hope you found this information helpful and useful. Remember… Expansive Soil is not a bad thing… It’s only bad if certain construction rules and end user rules are not followed.

Till our next posting... Bye for now…

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