Imperial Beach · 91932 · South Bay coast
ADU Builder in Imperial Beach, CA
Imperial Beach is the small beach city at the bottom of the bay, with water on three sides and its own ADU ordinance. Requests for IB backyard units, JADUs and garage conversions sent here go to a licensed San Diego general contractor. Below are the local rules, and the coastal permit that most Chula Vista owners never deal with.
Roofer laying shinglesShort answer
Yes. On most single-family lots in Imperial Beach you can build a detached ADU of up to 1,200 sq ft, 16 ft tall and 4 ft off the side and rear lines, and in the R-1 zones you can also add a JADU inside the house. The catch is the coast. About 87% of the city lies in the Coastal Zone, and there a coastal permit is required for any new ADU and for turning a garage into an ADU or JADU. The City charges $1,000 for that permit and reviews it in about 30 calendar days, and it must be approved before the building permit goes in. Parcels in the Coastal Commission's own jurisdiction go to the Commission instead.
Imperial Beach next to Chula Vista
Same high school district, different permit path.
| Item | Imperial Beach | Chula Vista (for comparison) |
|---|---|---|
| Detached ADU size | Up to 1,200 sq ft | Up to 1,200 sq ft |
| Attached ADU size | 50% of the house or up to 800 sq ft | Half the house, with an 850 sq ft (1BR) or 1,000 sq ft (2BR+) floor |
| Pre-approved plans | One 600 sq ft set posted by the City | 12 City Standard ADU Plans |
| Water | California American Water | Sweetwater Authority (west) or Otay Water District (east) |
| Elementary school fees | South Bay Union School District | Chula Vista Elementary, $2.37 per sq ft |
Imperial Beach figures from the City's ADU page and coastal permit handout. The Chula Vista column summarizes the Chula Vista ADU requirements guide, which covers Chula Vista only.
What the City's ADU rules allow
The City Council adopted an updated ADU ordinance, and the City's ADU page summarizes it by zone. How many units you can add depends on which residential zone your lot sits in.
| Zone (single-family home) | Detached ADU | Attached or conversion ADU | JADU |
|---|---|---|---|
| R-1-6000, R-1-3800, R-3000-D | One | One (attached or conversion, not both) | One, up to 500 sq ft, inside the house |
| R-3000, R-2000, R-1500 | One | One (attached or conversion, not both) | Not listed by the City |
From the City of Imperial Beach ADU page. Multifamily lots follow separate counts: up to eight detached ADUs on a lot with existing apartments, never more than the number of existing units.
- Height: 16 ft for a detached unit; 18 ft near a major transit stop or high-quality transit corridor (half a mile), with 2 more feet to match the house's roof pitch. Attached ADUs top out at 25 ft or the zone height, if that is lower, and two stories.
- Setbacks: 4 ft from side and rear lines.
- Converting an accessory building: the unit can grow by up to 150 sq ft past the old structure's footprint, and further only for an entrance or exit.
- Garage conversion size: a converted-space ADU can reach 1,200 sq ft; a converted-space JADU stops at 500.
The City's page is silent on parking. State law waives ADU parking within a half-mile walk of transit and for conversions, and bans replacement parking for a converted garage; confirm how that applies on your block.
The coastal permit, step by step
This is the step that surprises people who have read about Chula Vista. A state planning record for the City's General Plan update puts 87% of Imperial Beach inside the Coastal Zone, so most owners should assume they are in it until the map says otherwise. The City's handout lists four triggers: a new attached ADU, a new detached ADU, converting permitted non-habitable space (a garage, storage room or patio cover) into an ADU, and converting a garage into a JADU.
Check your zone color
Open the City's Parcel Viewer, turn on the "Coastal Zone Jurisdiction" layer and search your address or APN. Green means a City administrative permit. Red means a City permit that the Coastal Commission can appeal. Blue means the Commission itself handles the permit.
Apply online
In the City portal, choose the administrative land use application and upload a site plan, landscaping plan, existing and proposed floor plans, elevations, a roof plan, the grant deed, a preliminary title report dated within 90 days, and the Discretionary Permit Application Package.
Drop off the notice package
A public notice package goes to the Community Development counter, which keeps short morning and late-afternoon hours Monday to Thursday.
Pay and wait about 30 days
The fee is $1,000, with more if extra reviews are needed. The City counts 30 calendar days from payment. The coastal permit must be approved before you submit for a building permit, unless staff agree to run the two side by side.
On a Blue Zone parcel, the Coastal Commission runs a separate, longer process with its own fees.
Flooding and sea-level rise
The City's 2016 sea-level rise assessment found wastewater pipes, pump stations, 1.7 miles of road and oceanfront property exposed to tidal flooding and storm erosion. An inland block is a different case, but a lot near the beach, the bay edge or the Tijuana River side deserves an early look at flood maps before you set a floor height. We have not confirmed how flood rules apply to ADUs parcel by parcel; ask Planning.
Small lots and what fits
Imperial Beach lots run small. One of its single-family zones is named R-1-3800, and the number in the name points to lots of about 3,800 sq ft; confirm your own lot's area on the Parcel Viewer or your title report. On a lot that size, a 1,200 sq ft detached unit rarely fits once the 4 ft setbacks, the house and a path to the street are drawn in.
What usually works on a small IB lot:
- A 400 to 600 sq ft detached studio or one-bedroom in the back yard, often near the City's posted 600 sq ft plan.
- A garage conversion, which keeps the existing footprint and adds at most 150 sq ft. The garage conversion guide walks through slab, wall and window work; its permit rules are Chula Vista's, and in IB the coastal permit comes first.
- A JADU of up to 500 sq ft inside the house in the R-1 and R-3000-D zones, which is the lightest build. Layouts are on the JADU and attached ADU page.
Where the yard is gone, an attached two-story ADU can be the way up.
The pre-approved plan
AB 1332 required a plan pre-approval program by January 1, 2025. Imperial Beach posts one set, "Pre Approved ADU Plans (600 SF)", plus a checklist for submitting your own plans. No designer, price or review time is posted. You still need a site plan, and in the Coastal Zone, the coastal permit.
What an Imperial Beach ADU costs
The ADU cost calculator is calibrated to Chula Vista, and construction in Imperial Beach falls in similar South Bay ranges, since the same crews and suppliers work both cities. Mid-finish planning figures on a standard flat site:
| Project | Planning mid | Typical range |
|---|---|---|
| 500 sq ft detached studio or one-bedroom | About $260,000 | $224,000 to $296,000 |
| 740 sq ft detached one- or two-bedroom | About $327,000 | $281,000 to $373,000 |
| 400 sq ft garage conversion | $145,000 to $153,000 | $121,000 to $186,000 |
| 550 sq ft attached ADU | About $213,000 | $181,000 to $245,000 |
| 300 sq ft JADU | About $100,000 | $70,000 to $135,000 |
From the calculator at Chula Vista settings. Treat these as planning numbers, not a bid.
Where the IB fee lines differ from the calculator:
- Coastal permit: add $1,000 plus the preliminary title report and notice package. The calculator has no coastal line, since it is built on Chula Vista's fee schedule.
- Building permit: Chula Vista's flat ADU permit fees do not apply. We could not find a published IB ADU permit schedule, so ask the City for a fee estimate once plans are drawn.
- School fees: only on units over 500 sq ft. Sweetwater Union High posts $3.01 per sq ft; South Bay Union School District collects the elementary share, and the two together cannot pass the state Level 1 cap of $5.38 per sq ft set in January 2026. We did not find South Bay Union's posted rate, so confirm it.
- Impact fees: state law bars them on ADUs under 750 sq ft and on JADUs. Above that, they are charged in proportion to the house.
- Water: California American Water serves Imperial Beach. Ask Cal Am early whether a detached unit can stay on the house's meter or needs its own service, and what that costs; we found no published ADU connection fee.
Rents in Imperial Beach
Zumper's averages for Imperial Beach, updated November 7, 2026: studio $1,725, one-bedroom $1,975, two-bedroom $2,697. For a metro yardstick, HUD's FY2027 Fair Market Rent sits at $2,335 (1BR) and $2,823 (2BR). For a new backyard unit, a fair planning range is about $1,700 to $2,000 for a studio, $1,950 to $2,350 for a one-bedroom and $2,650 to $2,850 for a two-bedroom.
Rough math: a 500 sq ft one-bedroom at $2,000 a month is $24,000 a year, or about $20,500 after vacancy, upkeep and some $825 of new property tax. Against a $260,000 build, close to 8% a year before financing.
In pictures
Inside a small coastal unit
These are licensed stock photos (Pexels) chosen to show the kind of space or place described. They are not photographs of our contractor's completed projects.
Imperial Beach ADU questions
Do I need a coastal permit to convert my garage in Imperial Beach?
If the lot is in the Coastal Zone, yes. The City's handout lists converting a garage into an ADU, and converting a garage into a JADU, as triggers. A JADU carved out of bedrooms that are already living space is not on the list.
Is all of Imperial Beach in the Coastal Zone?
Most of it. A state planning record for the General Plan update says 87% of the city is inside the zone. Check your parcel on the City's Parcel Viewer, which also shows whether the City or the Coastal Commission handles your permit.
How long does the coastal permit add?
The City's handout says 30 calendar days from payment, and the coastal permit has to be approved before the building permit is submitted unless staff agree to concurrent review. Blue Zone parcels go to the Coastal Commission and take longer.
Can I rent my Imperial Beach ADU on Airbnb?
Plan on no. The zoning tables list short-term rentals as permitted in the commercial and mixed-use zones, not the residential zones where most ADUs are built. Confirm your zone and the current rules with Planning.
Sources
- City of Imperial Beach, Accessory Dwelling Units
- City of Imperial Beach, What Triggers a Coastal Permit for Accessory Dwelling Units
- City of Imperial Beach, Pre-Approved ADU Plans
- CEQAnet, Imperial Beach General Plan / Local Coastal Program Update (SCH 2019039143)
- Adaptation Clearinghouse, 2016 City of Imperial Beach Sea Level Rise Assessment
- Imperial Beach zoning, Chapter 19.23 commercial/mixed-use use regulations (GoCodebook)
- Business Wire, Cal Am boil water advisory for Imperial Beach and Coronado (2023)
- Sweetwater Union High School District, Developer Fees
- Lozano Smith, $5.38 Level 1 school fee cap (SAB, Jan 28, 2026)
- Zumper, Imperial Beach rent research (Nov 7, 2026)
- HUD User, FY2027 FMR data (San Diego metro)
Last checked November 7, 2026. Imperial Beach rules are summarized from City documents. Coastal jurisdiction, flood status and fees are parcel specific, so confirm them with the City's Community Development Department before you design.
Next step
Get your free Chula Vista ADU Fit Check
Three short steps, about a minute. A licensed San Diego County general contractor reviews what you send, checks your lot against the City's ADU rules, your HOA and your water district, and replies with a realistic range and the questions that would change it.
- Which ADU types your lot allows, and the size and height limits that apply
- Whether your HOA, a CFD or your water district changes the plan
- A line-by-line range, including fees and utility runs, before you pay for drawings
- No obligation and no pressure follow-up