City CouncilCity CouncilMarch 1, 2011March 1, 2011

Expansive Soils Expansive Soils UpdateUpdate

March 1, 2011March 1, 2011

Expansive Soils

• Expansive Soils are soils that expand when water is added, and shrink when they dry out. This continuous change in soil volume can cause homes built on this soil to move unevenly and crack.

Building CodeInternational Residential Code

R 401.4, Where quantifiable data created by accepted soil science methodologies indicate expansive, compressible, shifting or other questionable soil characteristics are likely to be present, the building official shall determine whether to require a soil test to determine the soil’s characteristics at a particular location. This test shall be done by an approved agency using an approved method.

Soils Investigation

Permit Process

• Required documents – none unless evidence already exists

• Soils determination – USDA maps and Engineering street testing requirements

• Inspection process

Soils Investigation

USDA maps

http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

(Link also available through the COSA GIS website)

Provides soils data for the United States.

Soils Investigation

Soils InvestigationUSDA Map

Small dwellings and small commercial

ToA: Very limited shrink swell (1.0)TuB: Somewhat limited (0.5)KmC: Somewhat limited (0.5)TuA: Somewhat limited (0.5)

Soils InvestigationInspection Process

• Contractor obtains a permit• Plan Review process• Contractor calls for inspection• Inspector reviews for minimum

compliance• Inspector leaves prior to concrete

placement

Soils Investigation

Changes

• USDA Maps• Engineering soils reports• Random concrete pour observations

Soils InvestigationOptions:

• Continue “as is”, use USDA maps and heavily rely on Contractors to protect themselves.

• Require soils testing on all or some properties.

• Require homeowner/contractor to provide engineered foundations on all projects. COSA would do no foundation inspections.

City CouncilCity CouncilMarch 1, 2011March 1, 2011