When do you need a survey for an ADU in San Diego?

Many homeowners ask if they need to get a boundary survey or grading plan before proceeding with the planning & permitting process for their accessory dwelling unit (ADU). While you will need a site plan to submit for permits, a boundary survey may or may not be required for ADUs in the County of San Diego, including Oceanside, Carlsbad, Encinitas, San Marcos, Vista and other nearby municipalities. Read on for considerations when you are thinking about if you need a survey for your ADU project.

Do I need a survey for my ADU?

Whether you need a boundary survey for your ADU will depend on your jurisdiction, site conditions, location for the ADU and even the building inspector you happen to get for your project. Over the past few years, you may have been able to get through plan check without a survey. However, each jurisdiction will leave the final decision up to the inspector who, upon visiting the site, may decide a building verification survey is necessary. The inspector could then stop the project and require a survey before any work can continue, resulting in delays and unforeseen costs.

Consequently, SnapADU recommends a survey on most ADU projects and includes them in the scope of work in jurisdictions in which they are required.

What is the survey requirement for an ADU?

When talking about surveys in relation to an ADU, this typically breaks down into two components. The primary component locates the property lines onsite is a Boundary Survey, and the secondary component which verifies the placement of a new structure in relation to the property lines is the Building Verification Survey. Survey requirements vary by jurisdiction.

Boundary Survey

A Boundary Survey formally locates the property lines of the parcel in question. When building a permanent structure on a property, such as an accessory dwelling unit, it’s essential to ensure that the structure is placed accurately and in compliance with the setbacks. To achieve this, a Boundary Survey is required to determine the location of the property lines, from which the distance of the new structure can be measured.

By completing a Boundary Survey, you’ll have a clear understanding of the property lines, which is critical to ensuring that the ADU is constructed in the correct location and meets all zoning and building code requirements. This survey is a vital step in the ADU building process and helps to ensure a successful and compliant construction project.

Building Verification Survey

A Building Verification Survey (BVS) verifies that the accessory dwelling unit is accurately placed on-site in relation to the property lines and in accordance with the approved plans. The BVS is a follow-up field survey conducted at the installation of the foundation to verify the ADU’s location. In order to complete a BVS, note that a Boundary Survey must first be conducted to locate the property lines.

A Building Verification Survey is a specific requirement that some cities – such as San Marcos and Carlsbad – place on projects that propose a new structure. San Marcos requires building verification surveys in all cases, while Carlsbad requires them when the ADU is within 1′ of a setback. As of October 2022, Oceanside has also started requiring Building Verification Surveys.

How much does a survey cost?

The cost of a survey will largely be based on the existing surveys and information that are recorded with the county surveyor’s office. In most cases, a boundary & building verification survey would cost between $4,000 – $10,000.

Full grading plans for civil engineering can add thousands more, as can revisions and processing for plans. Many other factors can influence cost. For example, if the last survey on record was from 1930 on a parcel 2 blocks away, this would be an expensive survey because the surveyor is effectively starting from scratch and has to map the entire area surrounding the parcel as well, which of course takes significant time. It’s important to get a quote on a survey for your specific property to ensure you know how much it will cost upfront. Your contractor will be able to solicit this quote for you and include in the overall scope of work.

When in the ADU project should a survey be conducted? How long does it take to get a survey?

A survey typically takes 1-2 days to conduct the field observations, and 1-2 weeks to compile and record the findings with the County surveyor’s office. However, surveyors are in high demand and often have a lead time upfront of 2-3 weeks to schedule a survey. All of this work can be performed during the Design portion of your project in order to include the findings in the construction documents.

When should I go ahead and get a survey for my ADU?

In some cases, it may be prudent to go ahead with a survey even though it is not required by the jurisdiction. If you have a challenging lot with a hillside, easements, or other constraints that make design & planning less straightforward, it may be necessary to proceed with a survey. This serves to, again, eliminate the number of surprises you encounter during your ADU build.

If an inspector requires a survey and you don’t have one, it can stop construction progress and delay the project weeks or even months, and potentially cause a redesign if we have to move the building to account for new setbacks. During this time, you will likely accumulate additional costs as you stop and restart the build process. Overall, putting off a survey usually ends up hurting your build in the long run. Thus, if you have the budget for it, it is well worth your time and money to have your property surveyed early on.

Even if the city never requires a survey, there could be downstream consequences after the ADU is built. A neighbor could bring up a property line issue, force a survey, and potentially find an encroachment. This means you could in theory have to move the building after it has been constructed – not something any homeowner wants to be faced with.

If you have a challenging lot, getting a survey is a bit like an insurance policy both during your build and down the line. Getting a survey gets you more information about your ADU and its location, so you can be sure you are building well within your property lines. It not only benefits your build as it eliminates any possible delay, but will benefit you in the future if a property-line dispute ever arises.