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

Many homeowners ask if they need to get a 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 survey is 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 survey for your ADU will depend on your jurisdiction, site conditions and even the building inspector you happen to get for your project. Most jurisdictions state they will not require a survey for an ADU. You likely can even get through plan check, all the way to permit-ready status without the need for a survey being raised by the city. However, each jurisdiction will leave the final decision up to the inspector who, upon visiting the site, may decide a survey is necessary.

If possible, we attempt to flush this out during plan check or by having a “pre-construction” meeting on-site with the inspector prior to starting work. However, not all inspectors will extend the courtesy of a pre-constructing meeting. The first on-site inspection takes place when the foundation is ready to pour, meaning the inspector could stop the project and require a survey before any work can continue, resulting in delays.

Consequently, SnapADU recommends a survey on most ADU projects. Investing in a preemptive survey before it is required will eliminate any last-minute decision on part of your inspector that will require you to invest in a late survey. This can throw off the timeline and budget of your build, so it is often best to look into a survey earlier than later.

What is the survey requirement for an ADU?

Survey requirements vary by jurisdiction and can be broken down into two components. The primary component which locates the property lines onsite (Property Survey), and the secondary component which verifies the placement of a new structure in relation to the property lines (Building Verification Survey).

When a permanent structure is installed on a property, it is imperative that this structure is placed correctly and in accordance with the plans that have been approved by the governing jurisdiction. In order to achieve this, a Property Survey is required to locate the property lines from which the distance of the new structure can be measured from.

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?

Depending on what kind of detail you need, the price of a survey can vary quite a bit. You should be able to nail down the cost of a survey early on with the help of your contractor. It will largely depend on the location of your ADU, taking into account both setbacks and the condition of your property. For around $6,000, a property survey would formally locate property lines and existing structures in relation to the accessory dwelling unit, including location of survey marker(s) and follow up field survey of ADU location at installation of foundation.

If work is required to locate a survey marker off-site then additional costs may apply. Full grading plans for civil engineering can add thousands more, as can revisions and processing for plans. We work to determine the most cost-effective placement of the ADU to minimize need for these surveys whenever feasible. This also helps your build stay on-schedule.

How do I avoid the need for a survey?

SnapADU handles the design process – as well as construction – in order to help anticipate and avoid additional requirements and fees. During our initial feasibility study, we analyze the site and determine the best layout for the ADU. While ADU regulations allow for reduced setbacks, it is not always advisable to push up against them.

We are in regular contact with all sorts of folks in the ADU space, from inspectors to surveyors to the heads of building departments. The common sense approach they often advise is to place the ADU far enough from a setback whereby the issue of encroachment is less likely to be considered, since there is clearly sufficient setback (even if the property line were found to be a few inches “off” from where it is claimed to be). We typically allow a minimum of 2’ of additional buffer space between the setback and the edge of the ADU. If that’s not possible, it’s almost certain a survey will be required by the city inspector.

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. 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 amount 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. For those building an accessory dwelling unit for a family member, a last-minute survey will push back their ability to move closer. 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.

We try to mitigate potential setback and grading issues by considering the overall costs when placing your accessory dwelling unit on the site plan. But 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.