Costa Mesa ADU Properties — Market Update (March 2026)

There are currently six ADU properties on the market in Costa Mesa. Four are active, one just went under contract, and one already sold. Here is what the numbers look like and what they tell us about where this market is heading.

The Listings

SOLD

270 Albert PL — $3,350,000 6 bed / 2.75 bath · 3,000 sqft · Built 2025 · Lot: 7,812 sqft

This is a brand-new build that closed at $1,116/sqft. A 3,000 square foot home on a nearly 7,800 square foot lot with 6 bedrooms signals a property designed to maximize livable space — and at that bedroom count with a 2025 build date, this was configured as a luxury ADU layout where the additional unit functions as extra square footage rather than a standalone rental.

UNDER CONTRACT

934 Governor ST — $1,290,000 2 bed / 3 bath · 1,848 sqft · Westside Costa Mesa

This one is interesting. The property has approved plans and permits already in hand for a full reconfiguration: a 1,878 sqft main residence (4 bed / 4.5 bath) plus a 590 sqft ADU (1 bed / 1 bath) and a 2-car garage. Total proposed square footage comes out to roughly 2,438. That ADU is clearly designed for rental income — a 1 bed / 1 bath at 590 sqft on the west side of Costa Mesa would rent in the $2,200–$2,500/mo range. For an investor buying at $1.29M with plans ready to go, the math on this one gets compelling fast once the build is complete.

ACTIVE

1789 Nantucket PL — $3,695,000 4 bed / 4.5 bath · 3,446 sqft · 1991 · Lot: 4,760 sqft

The highest-priced listing on this list at $1,072/sqft. Four and a half baths on a 4-bedroom layout tells you this ADU is configured for luxury living, not rental income. The lot is tighter at 4,760 sqft, so the square footage is maximized for the owner's lifestyle rather than producing a separate rentable unit.

236 Camellia LN — $2,595,000 5 bed / 3 bath · 2,157 sqft · 1940 · Lot: 7,924 sqft

An older 1940s home on a large lot with solid bedroom count. At $1,203/sqft, the price reflects the land value and the ADU potential on nearly 8,000 square feet. The 5 bed / 3 bath configuration and lot size suggest this one leans toward a rental-configured ADU layout — enough separation and room count to support a tenant without crowding the main living space.

168 Monte Vista AVE — $2,700,000 4 bed / 3 bath · 1,673 sqft · 1950 · Lot: 5,995 sqft · Trust Sale

This is the highest price per square foot on the list at $1,613/sqft. It is a trust sale, which often means the property is being sold as-is or with minimal updates. At 1,673 sqft with 4 beds and 3 baths on a 6,000 sqft lot, the ADU here is configured tighter — more of an extra-square-footage play than a cash-flow rental setup.

212 E 19th ST — $2,995,000 5 bed / 4 bath · 2,578 sqft · 1955 · Lot: 8,100 sqft

The largest lot on this list at 8,100 sqft. Five bedrooms and four baths on a mid-century home with an ADU that, given the room count and lot size, is set up to support rental income. A detached ADU on the east side of Costa Mesa at this lot size could realistically pull $3,900–$4,500/mo depending on finish level and layout.

What the Market Is Telling Us

Six ADU properties in one city at one time is a meaningful sample for a niche this specific. Here is what stands out.

Price range is wide. These properties span from $1.29M (934 Governor, with approved ADU plans but not yet built) all the way to $3.695M (1789 Nantucket). That range reflects two very different buyer profiles. On the lower end, you have investors and builder-buyers who see the value in completing a permitted project. On the upper end, you have end-users and lifestyle buyers who want the extra space an ADU provides without necessarily needing it to generate income.

The market is splitting into two ADU types. Roughly half of these properties have ADUs configured for rental income — separate entrances, practical layouts, bedroom and bathroom counts that make sense for a tenant. The other half are luxury ADU setups where the additional square footage is designed to extend the main home's living space. This distinction matters because it determines who your buyer pool is. A rental-configured ADU attracts investors running cash flow numbers. A luxury ADU attracts families and lifestyle buyers who want a guest suite, home office, or multigenerational setup.

Costa Mesa's broader market context supports ADU demand. The median home price in Costa Mesa sits around $1.5M as of early 2026, up about 1.6% year over year. Homes are averaging around 50 days on market — slightly longer than last year's 42 days, which tells us the market is more selective but still moving. About 35% of recent closings in the mid-coastal area were all-cash deals, meaning investors are active and competitive. For ADU properties specifically, the buyer pool is smaller but more qualified. These are not impulse purchases. Expect 45–60 days on market for a financed buyer and 21–30 days for cash.

One already sold. One is under contract. That is movement. In a market where homes are sitting slightly longer across the board, the fact that two out of six ADU properties in Costa Mesa have already transacted or gone under contract tells you demand for this product type is real. Investors and end-users are both actively buying ADU properties in this city.

The East Side vs. West Side Dynamic

Costa Mesa's ADU market plays out differently depending on which side of the city you are on.

East side Costa Mesa borders Newport Beach and commands higher rents. A well-built detached ADU on the east side can realistically generate $3,900–$4,500/mo. The buyer pool here skews toward higher-net-worth investors and families who want the proximity to Newport without the Newport price tag.

West side Costa Mesa has been developing rapidly and offers a lower entry point. The 934 Governor property going under contract at $1.29M is a perfect example — approved ADU plans on a west side lot where the rental income ($2,200–$2,500/mo for a 1 bed) meaningfully offsets the cost of ownership. West side is where the cash-on-cash numbers tend to look best for investors who are willing to do the work.

What This Means for ADU Investors in Costa Mesa

If you are looking at Costa Mesa for an ADU investment, the current market gives you options at multiple price points and multiple strategies. The key is knowing which type of ADU property fits your investment thesis before you tour anything.

If you are buying for cash flow, focus on properties with rental-configured ADUs on lots large enough to support a detached unit with a separate entrance. West side properties like 934 Governor (already under contract) are the template.

If you are buying for long-term appreciation and lifestyle flexibility, the east side luxury ADU properties offer a dual benefit — live in it, use the extra space however you want, and build equity in a market that has appreciated steadily.

Either way, Costa Mesa remains one of the more ADU-friendly cities in Orange County. No owner-occupancy requirement, generous size limits (up to 1,200 sqft detached), and two distinct rental submarkets within the same city.