Geotechnical Reports: What to Expect & Why They’re Important

If you’ve heard of the International Building Code (IBC), you might expect that this collection of standards contains parameters that govern site construction permits. The IBC, which surrounds building codes created by the International Code Council (ICC), establishes building standards for most jurisdictions throughout the United States, and in numerous other countries around the globe. Among the seemingly endless lists of codes in the IBC, we come upon IBC Section 107, which mentions:

“Submittal documents consisting of construction documents, statement of special inspections, geotechnical report and other data shall be submitted.”

Today, we’re going to talk about that latter bit: geotechnical reports. With most foundation builds, a geotechnical report must be collected, recorded, and submitted alongside the permit application. So, what can you expect from your geotechnical report, or soil investigation? Well, a soil investigation will include all of the following reports (take note, further inspections and reports may be required, depending on the location of a build):

Geotechnical Report Requirements Under IBC Section 107

1. A plot showing the location of the soil investigation.
2. A complete record of the soil boring and penetration test logs and soil samples.
3. A record of the soil profile.
4. Information on the groundwater table, frost depth, and corrosion parameters.
5. Soil design parameters, such as shear strength, soil allowable bearing pressure, unit weight of soil, soil deformation characteristics, and other pile support conditions.
6. Confirmation of the suitability of helical foundation systems for the specific project.
7. Recommendations for design criteria, including, but not limited to the mitigation of effects of differential settlement, varying soil strength, and the effects of adjacent loads.
8. Recommended center-to-center spacing of helical pile foundations to accommodate building loads.
9. Field inspection and reporting procedures to include procedures for verification of the installed bearing capacity, when required.
10. Load test requirements.
11. Any questionable soil characteristics and special design provisions that are necessary.
12. Expected total and differential settlement.
13. Axial compression, axial tension, and lateral load soil capacities, if those values cannot be determined from the rest of the report.

The ICC also points out: “Where special conditions exist, the building official is authorized to require additional construction documents to be prepared by a registered design professional.“ Geotechnical reports must be completed by a registered engineer, and this engineer may be a third party consultant. Reports must be submitted as required by various departments within a given jurisdiction.

How Are Geotechnical Reports Utilized?

Geotechnical reports may be utilized throughout the construction process. As Civilblog.org points out, “The [geotechnical] report serves as the permanent record of all geotechnical data known to be pertinent to the project and is referred to throughout the design, construction, and service life of the project.“ It’s a critical document that’s designed to ensure that builds are safe, procedures are calculated, and building integrity lasts for the duration of a building’s lifetime. In addition, geotechnical reports may be crucial in resolving design and construction disputes, as well as claims that may occur after project completion.

Construction Cost Savings Thanks to Geotechnical Reporting

While a construction firm may be inclined to forgo a geotechnical survey in order to ramp up design time, these soil surveys usually decrease construction costs, and they certainly add to the safety of building construction. Without a geotechnical report, engineers will be forced to design and construct to meet minimum code criteria. That may mean excessive support construction and redundant support structures—and that means higher construction costs. NorthStar Engineering points out, in their article on geotechnical reporting, that “Code minimums are often very conservative and may increase construction costs significantly.” Neglecting to prepare a geotechnical report may have further repercussions; NorthStar continues:

“By deciding not to obtain a geotechnical report, clients are ultimately assuming responsibility for any adverse soil conditions that may be encountered. They also assume the risk for any resulting defects in the structure that are related to such soil conditions.”

Helical Piles & Geotechnical Reporting

When it comes to our helical piles and patented Stelcor® micropiles, geotechnical reporting may not be required, but it’s highly recommended. A soil and geological analysis will ensure that your building receives enough support, and it’ll ensure that your budget stays on track. With a geotechnical report, you can rest assured that your piles are installed optimally to match the footprint and load of your building. If you’re curious about our helical piles, our micropiles, or geotechnical reporting standards, don’t hesitate to get in touch with us. IDEAL Foundation Systems™ is proud to bring you premier foundation support components.