Sooner or later in a foundation conversation, someone says soils report or geotech. Maybe the engineer wants one before designing a repair. Maybe the City asked for one at plan check. Maybe a seller handed you one in a disclosure packet and you have no idea what you’re looking at.
This post explains what a geotechnical report actually is, what goes inside one, who is allowed to sign it in California, and the kinds of situations where foundation work tends to call for one. It’s written for homeowners in La Jolla citywide. It won’t tell you whether your project needs a report. That call belongs to the engineer and the City, and we’ll show you where those rules live.
If you want the permit-side trigger walkthrough, our San Diego permit basics for foundation work post covers it in its soils step. If you want to know what the drilling day looks like, the foundation settlement repair timeline covers that phase. This post sits between them: the document itself.
What a geotechnical report is
A geotechnical report is a professional’s written study of the ground under and around a structure, and what that ground means for the foundation. The California Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG) describes the field this way: “Geotechnical engineering includes the investigation and engineering evaluation of earth materials including soil, rock, groundwater, and man-made materials and their interaction with earth retention systems, foundations, and other civil engineering works.”
“Soils report” and “geotechnical report” get used interchangeably in conversation. The City of San Diego’s Guidelines for Geotechnical Reports treats the phrase as an umbrella: “Geotechnical Reports: This is an inclusive term covering many types of geologic and geotechnical engineering documents.” Under that umbrella, the guidelines describe two basic families:
- Preliminary reports, prepared before design, which study the site and recommend how to build on it.
- As-graded or as-built reports, prepared during or after construction, which the guidelines say “include compaction test reports and foundation inspection reports.”
The professionals who write them do more than one job. The City’s guidelines say geotechnical consultants “provide design recommendations, approve project plans and specifications, and provide construction observation services.” So the report can be the start of an ongoing role during construction, not a one-time handoff.
What goes inside one
Every firm formats its reports a little differently. The City says so directly: “The geotechnical consultant will determine the organization and format of the report.” Still, the building code sets a floor for content, and the City’s guidelines describe the usual sections.
The California Building Code, as adopted in San Diego, starts with how the ground gets classified: “Soil classification shall be based on observation and any necessary tests of the materials disclosed by borings, test pits or other subsurface exploration.” It then lists the questions a study may need to answer: “Additional studies shall be made as necessary to evaluate slope stability, soil strength, position and adequacy of load-bearing soils, the effect of moisture variation on soil-bearing capacity, compressibility, liquefaction and expansiveness.”
Section 1803.6 of the code lists items the written report must include where applicable. A few you’ll recognize when you flip through one:
- “A plot showing the location of the soil investigations.”
- “A complete record of the soil boring and penetration test logs and soil samples.”
- “A record of the soil profile.”
- “Elevation of the water table, if encountered.”
- Recommendations for foundation type and design criteria.
- “Expected total and differential settlement.”
The City’s guidelines add narrative pieces: the purpose of the report, a site description, the proposed work, previous studies, the scope of what was done, site conditions, analysis, illustrations, logs, test data and references. Two sections deserve a homeowner’s closest reading.
Conclusions. “A conclusion regarding the suitability of the site for the intended use should be provided.” This is the plain-language answer to whether the site works for what you plan to build or repair.
Recommendations. “A preliminary geotechnical report addressing building plans should provide foundation and design recommendations.” This is the part your structural or civil engineer designs from. The guidelines also say “The geotechnical consultant should indicate if additional exploration, testing, or analyses are recommended.” If you see that language, the report is telling you it isn’t the last word.
How to read one without a degree
You don’t need to interpret boring logs to get value from a report. Start with the conclusions and recommendations, then look at the site plan to see where the borings or test pits actually went. Ask whether any of them are near the part of the house that’s moving. Note the date on the cover, because the City treats reports as having a shelf life (the timeline post covers the three-year rule). Then ask your engineer to walk you through any recommendation you don’t understand.
Who signs it in California
This is where titles matter, and California is specific about them.
Geotechnical engineer. Under Business and Professions Code §6736.1, nobody may use the titles soil engineer, soils engineer or geotechnical engineer “unless he or she is a licensed civil engineer in this state” who also meets the board’s added requirements. BPELSG’s consumer guide puts it simply: “Geotechnical engineers are civil engineers who have obtained additional experience and passed a specialized geotechnical engineering examination.” The City’s guidelines use the same idea: “Geotechnical Engineer: A PE who is additionally a State of California Registered Geotechnical Engineer (GE).”
Geologists. The City’s definitions also include the Professional Geologist (PG) and the Engineering Geologist, a PG who also holds the Certified Engineering Geologist (CEG) credential. Geologist licensing and the engineering-geologist specialty are set out in Business and Professions Code §§7841 and 7842. On hillside and fault-adjacent lots, a geologist’s work may sit alongside the engineer’s.
The signature itself. The City is clear: “All geotechnical reports submitted to the City of San Diego must be signed and/ or seal (stamped) by an appropriately licensed professional as prescribed by State Law.” Which license fits a particular report is a question for the professional and the City, not for a contractor or a blog post. Our PE, SE and contractor roles in California post covers the title rules in more depth, and our structural engineer page explains how engineering fits into a repair.
BPELSG’s consumer guide suggests checking the board’s website to verify that a professional is currently and properly licensed. That takes a few minutes and is worth doing before you rely on a report.
When foundation work is likely to need one
There’s no single list that covers every house. BPELSG’s guide says only that “Sometimes a geotechnical or soils report is necessary.” The City’s rules give clearer signals.
Fill and expansive soil. The City’s Information Bulletin 141 says “A preliminary geotechnical report or as-graded geotechnical report prepared by a registered design professional shall be submitted with all plans for buildings and structures supported on fill material.” The same bulletin applies the requirement to expansive soils. It also warns that “if the building inspector observes or suspects that fill materials or expansive soils are present in the building area, a geotechnical report prepared by a California registered design professional may be required.” So a report can come up mid-project, not just at plan check. Lots built on old grading are covered in our cut-and-fill lots post.
Anything the City decides needs one. The guidelines exempt certain minor projects, then add: “City review of project plans or field conditions may determine that a geotechnical investigation is required for any project.”
Repair design. Repairs are their own category. The ASCE Texas Section’s residential repair guideline, written for engineers in Texas, says “The engineer designing structural remedial measures will need geotechnical information.” It adds that “For major or comprehensive remedial measures, geotechnical information should be derived from a site specific boring and testing program tailored to the project’s needs.” California practice is set by California codes and the City, but the logic carries: a foundation settlement repair designed without soil information leaves the engineer guessing about the ground. ICC Evaluation Service reports for pier systems say it in their own terms: “A soil investigation report in accordance with IBC Section 1803 or IRC Section R401.4, as applicable, must be submitted for each project, when requested by the authority having jurisdiction.”
Slopes. Hillside lots raise slope stability, one of the code’s listed study topics. See our hillside foundation repair page and the Mount Soledad hillside considerations post.
What a report doesn’t do
A report isn’t a guarantee, and a permit isn’t either. San Diego’s local building code amendment says: “Issuance of a Building Permit does not constitute a representation by the City that the site does not contain geological hazards or that construction is safe.”
A report also doesn’t replace an inspection of the house. It describes the ground. A foundation inspection or structural inspection looks at what the house is doing. The two work together.
And a report doesn’t freeze in place. If the geotechnical consultant changes partway through a project, the City’s guidelines describe a Transfer of Geotechnical Responsibility letter so the new consultant formally takes over. During grading, the consultant’s observations feed the as-graded report.
Questions worth asking
- Has a geotechnical report been done for this lot before, and is it still current for this work?
- Does the engineer want new borings near the part of the house that moved?
- Who will sign the report, and what is their license?
- Will the geotechnical consultant observe the work during construction?
- Does the report recommend more exploration or testing?
Cost factors, not prices
We don’t publish prices. What shapes the cost of geotechnical work includes: whether an older report can be updated or a new study is needed; the number and depth of borings or test pits; access for drilling equipment on the lot; laboratory testing; slope or fault questions that add a geologist’s scope; construction observation visits; and City review comments that ask for more information.
Where we fit
We’re a foundation and structural repair company serving La Jolla citywide. We can visit, document what the house is doing, and help you understand where a soils report fits before the engineering starts. We aren’t engineers or geologists, and we don’t prepare or sign geotechnical reports. We work with verified contractors and coordinate with licensed engineers as needed. This post is general education, not an assessment of any property.
Next step
If you’re facing foundation work and aren’t sure whether soils information is part of the picture, request a Free Quote for an on-site visit anywhere in La Jolla, or call (650) 739-6537.
Sources (accessed October 29, 2026)
- City of San Diego, Guidelines for Geotechnical Reports (2008)
- City of San Diego Development Services, Information Bulletin 141
- San Diego Building Code (2025 California Building Code as amended), Chapter 18, via UpCodes
- California Board for Professional Engineers, Land Surveyors, and Geologists, A Guide for Consumers
- California Business and Professions Code §§6736.1, 7802, 7841, 7842, via California.Public.Law
- ASCE Texas Section, Guidelines for the Evaluation and Repair of Residential Foundations, Version 3 (2022)
- ICC Evaluation Service, ESR-4471 and ESR-5005 evaluation reports