Soil Report Costs: A Comprehensive Guide

Key Takeaways

The average cost of a soil test varies widely, ranging anywhere from $500 to $5,000 or more.

This is because there are many types of soil tests. Some of these tests, like basic soil profiles, are relatively inexpensive, costing no more than a few hundred dollars in total. Other types of tests, like geotechnical reports, are more comprehensive and require the help of a geotechnical engineer, who can charge $100 or more just for an hour of work.

Not every city in Southern California requires a soil report as part of ADU construction. Those that do require them to ensure safer construction and more stable, durable structures. Pre-construction soil testing gives builders and engineers the information they need to make important decisions when it comes to foundation design and how to best prevent drainage and erosion issues.

Understanding the purpose of soil testing helps homeowners budget more accurately and avoid unnecessary tests.

What is a Soil Report and When is it Necessary?

A basic soil report is an analysis of the top layer of soil. These reports tell you the soil makeup of your property, its nutrient level, and if it contains heavy metals or other contaminants. This kind of report is helpful for gardeners looking to improve their plant growth or lawn health, and also for parents of young children (since kids put everything in their mouths—even dirt!). Typically, these types of reports aren’t used in construction.

While knowing the soil composition is helpful when determining the type of foundation to use, that information is typically obtained by a much more involved form of soil testing known as a geotechnical report.

Two of the most common soil reports:

• Basic soil report: generally not used in construction
• Geotechnical report: used in construction

A basic soil test may help with landscaping, but only a geotechnical report can reveal if your ground is build-ready.

What Are Geotechnical Reports and Why Are They Important?

When it comes to building an ADU, many cities in the San Diego area don’t require any kind of soil report. Those that do typically require a geotechnical report.

A geotechnical soil report goes beyond the first few inches of soil to analyze the ground 10, 20, or even 50 feet below where the ADU will be built. Though far more expensive than a basic soil profile, these reports can be critical in places like California that have lots of seismic activity. They determine what size ADU the ground can support, what type of foundation will need to be used, how deep any footings need to be placed, how to prevent flooding and erosion, and if the soil is prone to liquefaction in the event of an earthquake.

Building with a geotechnical report in mind doesn’t just prevent settling, shrinkage, and other costly construction issues; it can prevent outright structural failure, especially in the case of larger ADU projects, where the structure is 1000+ square feet. See how big can an ADU be in California?

Deep soil borings are essential in seismic zones like San Diego to ensure foundation stability and compliance.

Geotechnical Report vs Soil Report

A soil report focuses on surface-level analysis, providing information on the soil’s basic composition, nutrients, pH levels, and contamination. These reports are typically performed by a soil testing lab and involve collecting a small soil sample or samples for lab processing. While certain information in these reports can be helpful to ADU builders and structural engineers, they are most often used by gardeners.

A geotechnical report, on the other hand, is a full analysis of the ground beneath a proposed ADU, including its structural properties, compaction, and load-bearing capacity. Depending on the location and size of the build, geotechnical reports examine the ground anywhere from 10 to 50+ feet below the surface by way of soil borings. Because the work is far more involved, geotechnical reports are performed by a geotechnical engineer or soil engineer.

While geotechnical reports are more typically associated with construction, some cities do request that both tests be performed before building can begin. This is sometimes referred to as advanced soil testing or a comprehensive soil analysis.

How Much Does a Soil Report Cost?

The cost of soil testing can range anywhere from $10 for a home soil report to $5000+ for a full geotechnical report by a geotechnical engineer. When it comes to the ADU projects in the San Diego area, though, we tell homeowners to expect anywhere from $800 to $3000.

Where your final costs fall in this range depends on a few key factors. Here’s what to consider when budgeting and figuring out your potential costs for a soil report.

• Site conditions
• Scope of testing
• Size and location of the site
• Labor and specialist fees
• Soil remediation

Site Conditions:

If your site has more complex soil types, has a steep slope, is at risk of erosion, or has other environmental hazards, these can all affect the complexity of the testing process and the report itself. In some cases, additional testing may be required, which comes with extra cost.

Scope of Testing:

Basic soil testing is far less expensive than detailed geotechnical investigations because it’s far less involved and doesn’t require the assistance of an engineer.

Size and Location of the Site:

If you have a large property, samples may need to be taken from several locations on the property, which can increase costs. Also, if you live in a remote area, the cost of your soil testing may include travel fees for engineers or other experts.

Labor and Specialist Fees:

Basic soil testing often doesn’t require much labor time or the use of any specialists. Geothermal reports do, which is why they are so much more expensive.

Soil Remediation:

If a soil report determines your soil is contaminated or too unstable to build upon, remediation may be required for your project to move forward. Remediation involves different things depending on what exactly is being remediated but always involves additional time, labor, and costs.

Soil testing costs vary based on site complexity, but investing early can prevent thousands in foundation repairs.

Soil Report Cost by Project Type

Soil testing costs vary dramatically based on the type of soil test being performed, and there are far more testing options than just the basic soil profiles and geotechnical testing we’ve discussed so far.

This table lists the many potential soil tests as well as their average costs. To get a more accurate cost for your project, schedule a consultation with an experienced ADU builder. They can include the cost of soil tests as a line item on your overall construction budget.

Table of Soil Tests, Their Purpose, and Cost

Is a Soils Report Required for Building My Accessory Dwelling Unit (ADU)?

Soils report requirements vary from city to city. This table reflects the requirements for various cities in San Diego County at the time of publication, but they may have changed (as building codes do!). The best way to understand the requirements for your city is to contact your local building department.

Table of Soils Report Requirements in San Diego County Cities

See more specific ADU regulations for cities in San Diego County.

How Long Does a Soils Test and Geotechnical Report Take to Complete?

Basic soil profile testing typically only takes 1-2 weeks to complete. This accounts for:

• 1-2 days to collect the samples
• 3-7 days for the lab analysis
• 2-5 days for the final report preparation

Geotechnical soil testing can take twice as long—up to 4 weeks— though, for particularly complex sites, it could be longer than that. This accounts for:

• 1-3 days of sample collection
• 1-2 weeks of lab analysis
• 1-2 weeks to draft the final report

Note: Timelines for both types of reports can be extended if the site is remote, difficult to access, or if there are weather delays (which is a particular concern when it comes to drilling).

Urban and suburban properties may benefit from faster turnaround times for soil reports due to easier access.

How to Save on Soil Report Costs

For many homeowners, soil test costs are a necessary expense to prevent much more costly repairs or failures down the road. There are ways you can reduce these costs, though, to ultimately save money on your overall construction budget. These include:

• Choosing local providers to avoid travel fees
• Combining testing with other pre-construction services
• Compare quotes from multiple vendors

One of the best things you can do, though, when it comes to saving money on soil reports (and so many other areas of construction) is to hire an experienced ADU builder. An experienced ADU builder like Better Place Design & Build will understand which soil tests are truly necessary and which aren’t, so you don’t waste time and money on the wrong tests.

Some cities also allow less expensive testing alternatives for ADUs. An experienced ADU builder will know if your city does and help you take advantage of these cheaper alternatives.

Save on soil reports by combining them with other pre-construction services—your ADU builder can guide this.

How Better Place Can Help with Pre-Construction Services

At Better Place, we pride ourselves on being ADU construction experts, and an important part of construction is pre-construction. This includes design, site analysis, permit applications, and, of course, soil testing.

We know the pre-construction phase can be stressful for many homeowners, but at Better Place, we are often able to complete our ADU projects within 8-12 months, from initial consultation to final inspection. Reach out to schedule your free consultation and see what’s possible on your property.

Partnering with a full-service ADU builder ensures seamless coordination between pre-construction assessments and on-site execution.