ADU builders and rules in Santee

Santee ADU rules

Santee's ADU rules are in Santee Municipal Code § 13.10.045. The city summarizes them in its ADU guide, current as of July 2026, which also points you to the state ADU statutes for anything the local code doesn't cover. Detached ADUs and conversions are allowed in single-family and multifamily zones; attached ADUs and junior ADUs go with single-family homes.

A few details in the guide are easy to miss. Fire sprinklers are required in the ADU only if the main house has or needs them. A new two-story ADU, or an ADU built as a second-story addition, needs a licensed engineer. Every ADU has to meet the 2022 CALGreen Tier II voluntary measures and Santee's energy rules in SMC § 13.10.040(J) and (K); the newer guide cites the 2025 edition of the green code. See two-story ADUs and attached vs. detached ADUs for how these choices play out. The state baseline behind all of this is in California ADU laws, and the junior ADU rules are in our junior ADU guide.

Santee pre-approved ADU plans

Santee doesn't run its own plan library. Instead, under the state's pre-approved plan law, it accepts three sets of pre-approved plans from other agencies:

• County of San Diego standard ADU plans, which the County gives away free.
• City of Chula Vista standard ADU plans.
• City of Encinitas Permit-Ready ADU plans.

These plans aren't a full permit set. The city's ADU guide says you still need a site plan showing where the ADU goes and a foundation plan for your lot, and that modifications to pre-approved plans are not permitted. The city's housing page adds that the County plans are a starting point: you complete them for your site and current codes. Our pre-approved ADU plans guide compares the regional programs, and ADU floor plans covers layouts.

Santee ADU fees

Santee waived ADU development impact fees for five years starting in September 2019, according to its 2021–2029 Housing Element. That fee waiver ended September 27, 2024, and ADUs now pay all fees normally collected at permit issuance. The city's ADU guide includes impact fee worksheets at rates effective July 1, 2026 (fiscal year 2026/27).

ADUs under 750 sq ft pay no impact fees, as Santee's guide and state law both say. Above that size, state law requires the fee to be proportional to the main house's square footage. The city's worksheet examples show the full single-family rate, so ask staff how they apply the proportional rule to your house before you budget. These totals don't include building permit and plan check fees.

School fees in Santee

School fees apply only to ADUs over 500 sq ft. If your home is in the Santee School District (kindergarten through eighth grade) and the Grossmont Union High School District, you pay both:

Grossmont Union's fee page says projects of 500 sq ft or less are exempt and that fees are due before the building permit is issued. For the full build budget, see what an ADU costs in San Diego or run the ADU cost calculator. Financing options are in our ADU financing guide.

Fire zones, airport review and utilities

Check three things about your lot before you design.

• Fire hazard zone. The Santee Fire Department posts a map of the city's fire hazard severity zones. In a Very High zone, new buildings need at least 100 feet of defensible space and ignition-resistant construction under Chapter 7A of the California Building Code; Chapter 7A also applies in High zones. That means ember-resistant vents, roofing, siding and windows, which can add cost.
• Airport Influence Area. The ADU guide asks you to call the Planning Division to find out if your lot is in an Airport Influence Area. If it is, aviation compatibility review, possibly including the FAA, may lead to sound insulation requirements or a recorded overflight notice.
• Water, sewer and power. The guide lists Padre Dam Municipal Water District and SDG&E as the utilities to call. The city tells you to contact them early about connections, fees and conflicts with utility equipment or easements. We couldn't find Padre Dam's ADU capacity fees online, so ask the district for a quote.

Getting a Santee ADU permit

All building submittals go through the Santee Permitting and Licensing Portal. The Building Division no longer accepts paper plans and says it is not offering expedited review. Questions go to the Planning & Building Department at City Hall, 10601 Magnolia Avenue, Building 4, phone 619-258-4100 ext. 167, open Monday to Thursday 8 a.m. to 5 p.m. and Friday 8 a.m. to 1 p.m.

The city's guide lays out the steps: check your zoning, talk to staff about a preliminary layout, prepare plans signed by the person who drew them (an engineer for grading plans if needed), and submit a complete application. The guide says Santee will tell you within 30 days whether the application is complete. Current state law sets 15 business days for that check, then 60 days to approve or deny a complete application. After you pay permit, school and impact fees, you build, call for inspections, and receive a Certificate of Occupancy at final sign-off.

Santee issued one ADU permit in 2018, four in 2019 and 14 in 2020, and its housing plan set a goal of 80 ADUs from 2021 to 2029. Before you sign with a builder, read how to hire an ADU contractor, check a contractor's license, and compare verified ADU builders in San Diego County.

Legalizing an unpermitted ADU in Santee

If you have an ADU or JADU that was built or converted without permits before January 1, 2020, Santee has a path to legalize it. Under the city's Substandard Building Checklist, you can get a confidential inspection from a licensed contractor, architect or engineer first, then apply with a site plan, a floor plan and the completed checklist. The checklist says no impact fees are required. A city building inspector does a pre-inspection, and you fix only the substandard conditions found under state health and safety law before the permit is finaled.

Common questions