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Costa Mesa Home Remodels

City planning guide · Local planning for Costa Mesa. Confirm the jurisdiction serving your address.

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Costa Mesa is a city of 1960s and 1970s houses, and it has moved nearly all of its permitting online. A reroof, a water heater or a panel upgrade can be permitted in 20 minutes or less. The harder questions come from the ground and from next door: a good share of the city sits on ground mapped as liquefaction-prone, and adding a second story means the neighbors get a letter.

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A renovated 1960s single-story house in Costa Mesa
In this guide

What changes a remodel in Costa Mesa.

The 1960s and 1970s produced 47.9 percent of Costa Mesa's homes

The Census Bureau counts 44,427 housing units in Costa Mesa for 2020 to 2024. 21,262 of them date from those two decades, 11,559 from the 1960s alone, and the median year built is 1972. Just 11.0 percent went up after 1999. Houses from this era can reach a remodel with aging supply lines, aluminum windows, thin attic insulation and original ductwork. The city offers instant online permits for repiping, water heaters and HVAC, so a larger remodel can take on one of those systems without a long wait.

Source: Census ACS 2020-2024, Year Structure Built, Costa Mesa

27 percent of Costa Mesa's land lies in a state liquefaction zone

We laid the California Geological Survey's liquefaction zones over the Census Bureau's boundary for Costa Mesa and sampled the city on an even grid of points spaced 0.002 degrees apart; 27 percent of those points fell inside a mapped zone. A liquefaction zone marks loose, saturated sand and silt with groundwater within 40 feet of the surface, which can fail in strong shaking. The state requires a site-specific geotechnical investigation for most new development in these zones, with an exemption for single-family wood frame houses of up to two stories. Sellers must disclose the zone, so check the map before planning an addition or ADU.

Source: California Geological Survey, Seismic Hazards Mapping Act

A second-story addition in Costa Mesa triggers a notice to neighbors

After Planning staff approve a second-story addition, and before the Building Division issues the permits, the city mails a notice to every abutting property owner and posts the written decision on its website. Costa Mesa's ADU ordinance also regulates upper floors: it meets state minimums but adds objective design standards such as setbacks for second floors and two-story units. The same ordinance allows an ADU as small as 150 square feet and makes parking optional. Talk to the Planning Division at 714-754-5245 before you design upward.

Source: City of Costa Mesa, Second Story Additions

What a remodel costs in Costa Mesa in 2026.

89

ADU units permitted in 2025Costa Mesa ADU units that received building permits during 2025, as reported to the state in its Housing Element progress report; 92 in 2024

Costa Mesa's median owner-occupied home was valued at $1,115,100 in Census data covering 2020 to 2024. In 2025 the city issued building permits for 89 ADU units, against 13 new single-family houses, according to its annual report to the state housing department; in 2024 the count was 92 ADUs. Backyard units now outnumber new single-family houses by more than six to one.

Finish work is where the regional numbers fit best. In the 2023 American Housing Survey, the median metro owner spent $4,535 on flooring, paneling or ceilings. Tile labor sets part of that price: tile and stone setters in the metro earned a median $28.18 an hour in May 2025, compared with $26.77 nationally.

The numbers behind this section
ADU units permitted in 202589Costa Mesa ADU units that received building permits during 2025, as reported to the state in its Housing Element progress report; 92 in 2024 (California HCD, Housing Element Annual Progress Report data, Table A2)
New single-family homes permitted in 202513New detached houses that got building permits in Costa Mesa during 2025, per the same state filing; 31 in 2024 (California HCD, Housing Element Annual Progress Report data, Table A2)
Median home value$1,115,100Owner-occupied homes in Costa Mesa, Census ACS 2020-2024 (Census ACS 2020-2024, Median Value, Costa Mesa)
Median flooring project, Los Angeles metro$4,535Median owner-reported spending on floors, carpet, paneling or ceilings in greater Los Angeles and Orange County, from the 2023 AHS (Census American Housing Survey 2023, Table Creator)
Median tile setter wage$28.18 an hourTile and stone setters, Los Angeles-Long Beach-Anaheim, May 2025; $26.77 nationally (BLS OEWS May 2025, Los Angeles-Long Beach-Anaheim tile and stone setters)

Who issues permits in Costa Mesa.

Costa Mesa's Building Safety Division is the permit office for houses in the city. All of its applications run through TESSA, an online portal that also handles licenses and inspections. Paper forms and scanned applications are not accepted. Planning review, including second-story additions and ADUs, runs through the same portal.

  • Insta-Permits cover residential reroofs, repiping, water heaters, HVAC changeouts, panel upgrades, EV chargers, solar, temporary power and pool demolition. The applicant uses the city's standard plans, and once those are filled in, application and issuance take 20 minutes or less.
  • Most Insta-Permits come in two versions, one for licensed contractors and one for owner-builders.
  • TESSA lists window and door work as two permit types: retrofit replacements in existing openings, and new windows or doors.
  • Attached patio covers, non-habitable accessory structures and block walls built to city standards each have their own TESSA application.
  • The Safe ADU Legalization Program helps owners permit an ADU or junior ADU built without permits before January 1, 2020. An optional confidential inspection by a private contractor can size the work first, and the city will not penalize the owner as long as permits are pulled to fix health and safety problems.
  • Costa Mesa runs a pre-approved ADU plan program, and its ADU rules allow units as small as 150 square feet with parking optional.
  • A second-story addition gets Planning approval first, then a mailed notice to abutting owners, before building permits are issued.

What Costa Mesa homeowners plan most.

Kitchen remodel

In a 1960s or 1970s Costa Mesa house, a kitchen job usually reaches the supply lines and the panel, and both have their own Insta-Permits. Our kitchen guide covers Orange County; Costa Mesa Building Safety issues the permit.

Read our Orange County kitchen remodel guide

Bathroom remodel

A repipe can be permitted instantly online, which helps when a bathroom remodel exposes old supply lines. The bathroom guide covers Orange County, and permits here go through TESSA.

Read our Orange County bathroom remodel guide

Window replacement

Costa Mesa files retrofit windows in existing openings and new windows or doors as two separate TESSA applications, so pick the one that matches your job.

Roofing

A residential reroof is an Insta-Permit in Costa Mesa, issued in 20 minutes or less once the city's standard plan is filled in.

Flooring

The regional median flooring project was $4,535 in the 2023 housing survey, and tile setters in the metro earn more than the national median.

ADU or garage conversion

Costa Mesa permitted 89 ADU units in 2025 and allows units as small as 150 square feet. Units built without permits before 2020 can be legalized through the Safe ADU program.

Before you start.

What does remodeling a Costa Mesa house cost?

It depends on the scope. Regional survey data helps: in 2023, owners in greater Los Angeles and Orange County reported a median of $4,535 for flooring work, counting jobs they did themselves. Tile setters there earned a median $28.18 an hour in May 2025. Costa Mesa homes had a median value of $1,115,100 in the 2020 to 2024 survey.

What is an Insta-Permit in Costa Mesa?

It is a fast-track permit issued online through TESSA. For work such as a residential reroof, repipe, water heater, HVAC changeout, panel upgrade, EV charger or solar system, the applicant fills in the city's standard plans, and the application and permit take 20 minutes or less. Most types have separate versions for contractors and owner-builders.

Do I need to notify my neighbors for a second story in Costa Mesa?

The city does it for you. Once Planning staff approve a second-story addition, and before the Building Division issues permits, Costa Mesa mails a notice to all abutting property owners and posts the written decision online. Plan for that step in your schedule, and call the Planning Division at 714-754-5245 early in design.

Is Costa Mesa in a liquefaction zone?

Part of it is. When we compared the California Geological Survey's liquefaction zones with the city boundary, 27 percent of the city's area fell inside one. State law then calls for a soils study before most new building, sellers have to disclose it, and one or two story wood frame houses are exempt from the state study.

How do I legalize an unpermitted ADU in Costa Mesa?

Use the Safe ADU Legalization Program, which covers ADUs and junior ADUs built without permits before January 1, 2020. You can first get an optional confidential inspection from a licensed contractor, then submit plans through TESSA. The city reviews them against state health and safety standards and will not penalize you if permits are pulled to fix problems.

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