One of the most common questions we get from homeowners and builders is simple: “Do I actually need a soils report for my project?” The answer depends on what you’re building, where you’re building it, and what your local building department requires. This guide breaks it down in plain language.

What is a soils report?

A soils report — more formally a geotechnical investigation — is a study of the ground beneath your project. A licensed geotechnical professional drills or digs borings, samples the soil, runs laboratory tests, and produces a report with engineering recommendations for foundations, grading, drainage, and more. Building departments use it to confirm your project will sit on stable ground.

Common situations that trigger a soils report

In most Southern California jurisdictions, you will likely need a soils report if your project involves any of the following:

• New single-family homes — almost always required, especially on previously undeveloped or graded lots.
• Room additions — often required when adding significant load or a second story, or when the existing foundation needs evaluation.
• Accessory Dwelling Units (ADUs) — frequently required, though some jurisdictions waive the requirement for small, single-story units on flat, stable lots.
• Hillside lots — nearly always required. Slopes raise concerns about stability, landslides, and grading that a geotechnical engineer must address.
• Pools and spas — commonly required on hillsides or where expansive or unstable soils are suspected.
• Retaining walls — walls above a certain height (often four feet, or any wall retaining a surcharge) typically require geotechnical input.

When you may NOT need one

Small, low-load projects on flat, stable lots — like a detached patio cover, a minor interior remodel, or a small shed — often don’t require a soils report. The same is sometimes true for compact ADUs in certain cities. That said, the only reliable way to know is to check with your local building department before assuming.

Why local rules matter so much

Southern California spans dozens of jurisdictions, each with its own grading ordinances and submittal requirements. The City of Los Angeles (LADBS), the County, and individual cities like Santa Clarita all have distinct thresholds. A project that needs no report in one city may require a full investigation in the next one over — particularly in hillside or Special Grading Areas.

What a soils report typically includes

A complete geotechnical report generally covers site and subsurface conditions, soil classification and lab results, groundwater observations, foundation and slab recommendations, grading and compaction criteria, and seismic design parameters. On hillside sites it will also address slope stability and setbacks.

The bottom line

If you’re building new, adding load, working on a slope, or constructing a retaining wall or pool, plan on a soils report. When in doubt, a quick call to your building department — or to a licensed geotechnical firm — will save you time and costly surprises later in the permitting process.

GeoTed provides geotechnical and environmental consulting across Southern California. If you’re unsure whether your project needs a soils report, reach out and we’ll point you in the right direction.