Costa Mesa ADU Homes for Sale — Prices, Rents & Closed Sales (September 2026)
Costa Mesa is one of Orange County's tightest ADU markets — a city where strong rental demand, Newport Beach adjacency, and a firm ban on short-term rentals pushes long-term ADU rents higher than you'd expect for a mid-range market. As of September 2026, there are five active listings with ADUs, one pending sale, and two that just closed. Here's the full breakdown.
Active Listings
3097 Molokai Pl, Costa Mesa 92626 — $2,995,000
This Mesa Verde property is one of the most turnkey ADU setups currently on the market in Costa Mesa. The main house is a 3-bed/2-bath, 1,576-square-foot single-family home built in 1958. Complementing it is a brand-new, fully permitted detached ADU built in 2024 — 986 square feet, 2 bedrooms, 2 en-suite bathrooms, 10-foot ceilings, and a completely private entrance. The ADU carries a separate address and is priced for the rental market at $3,500/month.
At $2,995,000, this is a premium ask for Mesa Verde. But the 2024 ADU is the real asset — you're not inheriting someone else's conversion project. It was purpose-built from the ground up, and comes with soaring ceilings and complete separation from the main residence. If you're buying for rental income, the $3,500/month figure makes this worth modeling closely before you dismiss the price.
ADU at a glance: 2 bed / 2 bath | 986 sq ft | Built 2024 | Detached | Separate address | Rent: $3,500/mo
1430 Shamrock, Costa Mesa 92626 — $1,889,000
Nestled in Halecrest, this is one of the most extensively renovated properties to hit Costa Mesa this summer. The main house checks in at 5 bedrooms, 3 bathrooms, and 1,582 square feet — fully remodeled with a new roof, new plumbing, a 6-burner Thermador range, earthquake retrofitting, and an updated foundation. The backyard has a half basketball court.
The ADU is a more modest 325-square-foot studio built in 2018, detached, with its own separate access. It's positioned as a guest house or flex space rather than a market-rate income unit. If your strategy is owner-occupying a beautifully renovated home while collecting rent from a compact ADU, this fits that model well.
ADU at a glance: 1 bed / 1 bath | 325 sq ft | Built 2018 | Detached | Separate access
2049 Monrovia, Costa Mesa 92627 — $2,375,000
This one is different from everything else on the list. At 2049 Monrovia, you're not buying a main house with a backyard ADU — you're buying two fully separate, fully independent homes built new in 2022 on a single lot in Westside Costa Mesa.
The front home is 1,630 square feet, 2 bedrooms, 2 baths, with soaring cathedral ceilings, French doors, a chef's kitchen with quartz counters, and its own solar panel system. The back home — the ADU — is 1,100 square feet, 2 bedrooms, 2 full baths, with California Closets, a large kitchen island, and its own master walk-in closet. Both units have their own washer/dryer and their own solar system.
This is structured as a primary residence plus ADU, but it reads like a small duplex. If you want to house-hack or co-invest with a family member while maintaining complete separation, this is one of the cleaner setups you'll find in Orange County.
ADU at a glance: 2 bed / 2 bath | 1,100 sq ft | Built 2022 | Solar | Independent utilities
1578 San Bernardino, Costa Mesa 92627 — $3,500,000
This is the largest and most complex listing in today's update. Located in East Costa Mesa, 1578 San Bernardino is a 4,000-square-foot, two-story duplex built in 2004 — 6 bedrooms and 5 bathrooms across the main structure — plus two attached ADUs, each 2 bed/2 bath and approximately 1,000 square feet. Both ADUs have separate electric meters and separate street-level entrances.
The listing describes a contemporary Italian-influenced design with high-volume open areas, a private lap pool and spa, and ocean views. A 3-car attached garage rounds it out.
At $3,500,000, this is a multi-unit investor play. Three separately rentable units in a well-located East Costa Mesa cul-de-sac is a compelling setup for someone building a small rental portfolio. Price them right and you could cash-flow on day one.
ADU at a glance: Two ADUs, each 2 bed / 2 bath / ~1,000 sq ft | Built 2004 | Attached | Separate entrances and meters
1697 Labrador, Costa Mesa 92626 — $1,899,999 (Active Under Contract)
This Mesa Verde corner lot home is already under contract, but it's worth understanding what got it there. The 3-bed/3-bath, 1,996-square-foot main home sits on a 9,828-square-foot lot. The ADU is roughly 420 square feet — a permitted addition with a separate entrance, kitchen, large living space, fireplace, bathroom, and closet.
The listing calls out the ADU's versatility: private guest space, home office, multi-generational suite, or potential rental income. The property also has solar and is positioned in one of Mesa Verde's most sought-after pockets. It went under contract quickly.
ADU at a glance: ~420 sq ft | Permitted addition | Separate entrance | Solar on main home
Pending Sales
247 23rd St, Costa Mesa 92627 — $3,250,000
This Eastside Costa Mesa double-lot property just went pending, and the ADU income story here is significant: the ADU is a fully separate 3-bed/2-bath, 1,187-square-foot unit built in 2015 that's currently leased at $5,750/month through October 31, 2027.
The main residence is a Cape Cod-inspired home spanning approximately 2,569 square feet on a 13,500-square-foot double lot — directly across from Lindbergh Park, moments from the Back Bay, and a short drive to Newport Beach. The incoming buyer inherits income on day one, with the lease in place through next fall.
At $5,750/month, this is one of the higher ADU rents you'll see on a Costa Mesa listing. It reflects Eastside premiums: larger double lot, park-facing setting, and Newport Beach adjacency.
ADU at a glance: 3 bed / 2 bath | 1,187 sq ft | Built 2015 | Rented $5,750/mo through 10/31/27
Closed Sales
1198 Dorset Ln, Costa Mesa 92626 — Sold $1,365,000
Listed at $1,399,900, this Halecrest-area home sold at $1,365,000 — about 2.5% below asking — with $3,340 in seller concessions ($2,500 toward closing costs, $840 home warranty). The main home is a 5-bed/3-bath, 1,962-square-foot property built in 1963. The ADU is a Junior ADU: a 1-bed/1-bath unit of approximately 385 square feet on the upper level, with its own private stairway and separate entrance.
Junior ADUs — interior conversions carved from within the main home's footprint — are priced differently than detached ADUs, and this sale reflects that. $1,365,000 for a 5/3 with a JADU in Halecrest is a reasonable comp for the neighborhood, particularly with the home's trust-sale history and alarm-code access requirements.
ADU at a glance: JADU | 1 bed / 1 bath | ~385 sq ft | Upper level | Separate entrance
1184 Dorset, Costa Mesa 92626 — Sold $1,749,000
This one closed at full asking price in cash — a clean comp. The main home is a fully reimagined 5-bed/3-bath, 2,055-square-foot single-story on a corner lot in Mesa North, completely renovated with wide-plank flooring, a generous quartz island, and recessed lighting throughout. The standout feature: a brand-new 2025 ADU — a fully permitted 2-bed/1-bath unit of approximately 655 square feet (per plans), with its own entrance, separate address, owned solar panels, and separate washer/dryer.
The listing made the case that an ADU of this quality on a Costa Mesa corner lot is "genuinely rare to find." The cash close at full price suggests the buyer agreed.
ADU at a glance: 2 bed / 1 bath | ~655 sq ft | Built 2025 | Attached | Separate address | Solar (owned)
What This Market Is Telling You
A few patterns stand out from September's Costa Mesa ADU data:
Rents are strong. The $3,500/month ask at Molokai and the in-place lease of $5,750/month at 23rd Street both reflect what quality ADUs command in Costa Mesa. Newport Beach adjacency is a real premium — Eastside rents run meaningfully higher than what you'd see in inland markets like Garden Grove or Anaheim for a comparable unit.
New ADUs close at full price. Both Dorset Lane closings are illustrative. The 2025 ADU at 1184 Dorset sold for full ask in cash. The JADU at 1198 Dorset received a modest discount and some concessions. When you're selling a home with a newly built ADU, recent permits and move-in-ready condition are the difference between full-price offers and negotiated discounts.
Costa Mesa bans short-term rentals. Unlike many Orange County cities still working through STR policy, Costa Mesa prohibits short-term rentals outright. Every ADU rent figure in this report reflects long-term tenancy — and that actually stabilizes the income story for buyers who want predictable cash flow rather than Airbnb-dependent returns.
Inventory is thin but diverse. From a 325-square-foot studio to a dual-ADU 4,000-square-foot duplex, Costa Mesa's current ADU listings span a wide range of sizes, configurations, and price points. The key for buyers is matching your financing and ADU strategy to the right property type — and understanding how Costa Mesa's local ADU rules interact with what's already permitted on the property you're considering.
Thinking about buying or selling a Costa Mesa home with an ADU? Reach out to Dylan Serna — ADU specialist for Orange County — to talk through what's available and how ADU income affects your purchase power.
