What Is a Geotechnical Report? What San Antonio Builders Need to Know
What Is a Geotechnical Report?
A geotechnical report, also called a soils report or soil investigation report, is a technical document that describes what the soil and groundwater are doing below a construction site and provides engineering recommendations for how to design safely given those conditions.
The report comes from a site investigation that involves drilling boreholes, collecting soil samples at different depths, running field tests, and analyzing those samples in a laboratory. A licensed geotechnical engineer interprets the data and puts together recommendations for foundation type, design parameters, and any special construction considerations the project needs.
In San Antonio, geotechnical reports are a standard part of the construction process for both residential and commercial projects. Structural engineers require them. Permitting offices often require them. Lenders frequently require them.
- Boring Logs With Soil Descriptions
- Laboratory Test Results
- Subsurface Profile Interpretation
- Foundation Type Recommendations
- Bearing Capacity & PVR Values
- PE-Sealed by a Licensed Texas Engineer
What Does a Geotechnical Report Include?
Site Description
A description of the project location, the proposed construction, and the scope of the investigation performed.
Boring Logs
Detailed records of each borehole drilled, showing soil types at each depth, SPT blow counts, sample descriptions, and groundwater observations.
Laboratory Test Results
Results of tests performed on collected soil samples including moisture content, Atterberg limits, grain size, and other relevant properties.
Subsurface Profile
An interpretation of the subsurface conditions across the site based on the boring data.
Engineering Recommendations
Specific recommendations for foundation type, bearing capacity, PVR, pier depths, earthwork, drainage, and any other design considerations. These are written for the structural engineer and contractor to use directly.
Why Is a Geotechnical Report Required in San Antonio?
San Antonio Clay Soils Move
The main reason geotechnical reports matter so much in San Antonio is the expansive clay. Taylor Marl and Eagle Ford clay swell dramatically when wet and pull apart during dry stretches. That movement is measured and quantified through the PVR calculation. Without that number, a structural engineer cannot design a foundation that accounts for what the soil will actually do over time.
Permitting Offices Ask for It
Many jurisdictions in the greater San Antonio area require a geotechnical report as part of the building permit application. Requirements vary by jurisdiction and project type.
Structural Engineers Need It
San Antonio structural engineers need the soil data before they can design a foundation. Bearing capacity, PVR, and pier depth recommendations in the report are the inputs that drive foundation design decisions.
Lenders Require It
Construction lenders and some permanent mortgage lenders require a geotechnical report as part of their documentation for new construction financing. Requirements vary by lender and loan type.
Who Should Prepare a Geotechnical Report?
In Texas, a geotechnical report used for foundation design should be reviewed and sealed by a licensed Professional Engineer registered with the Texas Board of Professional Engineers.
Be cautious of firms offering soil reports without a PE seal. That document may not meet the requirements of your permitting office, structural engineer, or lender. Our reports are reviewed and sealed by a licensed Texas PE.
Frequently Asked Questions About Geotechnical Reports
How much does a geotechnical report cost in San Antonio?
Costs vary depending on the project scope, type of structure, number of borings, and site conditions. Contact us for a free quote. Most quotes are ready within one business day.
How long does it take to get a geotechnical report?
Most of our residential reports are ready within 5 to 7 business days after field work. Commercial reports typically take 10 to 14 business days.
Is a geotechnical report the same as a soil test?
The terms get used interchangeably. A soil test refers to the field and lab work. A geotechnical report is the final document that includes those results along with the engineering analysis and recommendations.