Bolthole Index

Orange County, California

Building permits, zoning and land rules in Costa Mesa, California

Costa Mesa, California requires building permits for home construction, with applications handled by the city’s Building Safety Division.12 Costa Mesa sets its own zoning, while Costa Mesa Sanitary District reviews sewer plans for projects it serves.34 For a proposed septic system inside Costa Mesa, we could not confirm the approving authority; ask Building Safety before choosing onsite wastewater.2

At a glance

Building permits
Required for home construction; city Building Safety handles applications12
Zoning
City zoning applies inside Costa Mesa3
Wastewater
CMSD sewer-plan approval; onsite septic authority unconfirmed4
RV living
State restrictions apply; a Costa Mesa private-lot exception is unconfirmed5
Small ADUs
Efficiency ADUs may be as small as 150 square feet if otherwise compliant6
Owner-builder
Conditional contractor-license exemption; building permits still apply7
Wells
Orange County Environmental Health enforces the well ordinance8

Who to call

Building permits

Costa Mesa Building Safety Division

Building-plan submittals and building permits inside Costa Mesa

(714) 754-5273

[email protected]

77 Fair Drive, Costa Mesa, CA 92626

Planning & zoning

Costa Mesa Planning Division

City zoning, zoning compliance and planning applications

(714) 754-5245

[email protected]

77 Fair Drive, Costa Mesa, CA 92626

Septic permits

Costa Mesa Sanitary District

Sewer permits and sewer-plan review; ask the city to identify the septic authority for a parcel proposing onsite wastewater

(949) 645-8400

[email protected]

290 Paularino Ave. Costa Mesa, CA 92626

Well permits

Orange County Environmental Health Well Permitting

County well-ordinance enforcement for Costa Mesa

714-433-6287

[email protected]

Roads & driveways

Costa Mesa Engineering Development Review

Development review and public right-of-way work permits

77 Fair Drive, Costa Mesa, CA 92626

Contact details are copied from each office’s official page and were checked against it on October 11, 2026.

Off-grid gear

Going off-grid in Costa Mesa means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in Costa Mesa, CA?

A new home in Costa Mesa needs a building permit before construction; California’s building-permit requirement also covers alterations, repairs, moving, conversion and demolition, subject to the applicable local requirements.1 Costa Mesa has adopted the California construction codes, including residential, energy, plumbing and electrical standards, with local modifications.9 Ask Costa Mesa Building Safety to identify the building-permit type for your proposed work and submit plans through TESSA.2

California’s owner-builder exemption can exempt qualifying owners from contractor licensing, but does not exempt the project from building permits or code requirements.7 Costa Mesa construction-code fees take effect through city council resolution, and supplemental fees may apply when prescribed fees do not cover service costs.10

Who handles Costa Mesa building permits and zoning questions?

Costa Mesa Building Safety is the city contact for building-plan submissions and building permits: call (714) 754-5273 or email [email protected].2 Costa Mesa Planning implements the city Zoning Code and checks building plans for zoning compliance; call (714) 754-5245 or email [email protected].11 City Hall is at 77 Fair Drive, Costa Mesa, CA 92626.2

Costa Mesa uses TESSA for building-plan submissions and building permits, and the Planning Division describes access to historical building data, plans and permits through the system.211 Ask Planning about the parcel’s zoning and Building Safety about the proposed construction; zoning compliance and building-code review are separate parts of the city’s work.119

Does Costa Mesa have zoning, minimum lot sizes and height limits?

Costa Mesa has city zoning, with district boundaries shown on the official zoning map filed in the Planning Division.312 The R1 single-family residential district specifies a minimum lot area of 6,000 square feet; the residential standards for R2-MD, R2-HD and R3 specify 12,000 square feet.1314 Those are district-specific standards, so ask Planning to identify the district before applying a lot-size rule to a property.1211

Residential land uses in Costa Mesa’s R1 district are limited to 2 stories and 27 feet, with qualifying lofts excluded from the story count.15 For setbacks and any parcel-specific development conditions, request a zoning review from Costa Mesa Planning before committing to a house layout.11

How do sewer and septic approvals work inside Costa Mesa?

Costa Mesa Sanitary District provides wastewater service in Costa Mesa, and sewer-plan approval and fee payment are required before construction of new structures, plumbing fixtures or other improvements within the service described by the district.4 A project that constructs or reconfigures a sewer lateral requires submission of a sewer plan during plan review.16 Contact the district at (949) 645-8400 or [email protected] to discuss sewer-plan requirements for the parcel.16

We could not confirm who approves a proposed septic system inside Costa Mesa; ask city Building Safety to identify the reviewing agency before assuming onsite wastewater is available.2 California’s onsite-wastewater policy allows local agencies to administer septic permitting under regional oversight, so a statewide septic framework does not establish Costa Mesa’s parcel-specific approval route.17

Can you live in an RV or tiny home in Costa Mesa?

California does not treat an RV as a permanent dwelling, and RV occupancy generally belongs in mobilehome or special occupancy parks unless a local ordinance allows otherwise.5 We could not confirm a Costa Mesa exception for residential RV use on a private lot or temporary camping while building; ask Costa Mesa Planning about the proposed use and address.11 Costa Mesa trailer and mobilehome parks require a conditional-use permit and remain subject to city zoning.18

A tiny home in California must meet an approved legal classification and have an approved location before occupancy.19 Costa Mesa allows qualifying efficiency ADUs as small as 150 square feet when all other legal requirements are met; that ADU rule does not establish a universal minimum for primary homes or permission to occupy a tiny home on wheels.6

What are the steps to build a home in Costa Mesa?

Start with the parcel and proposed use, then coordinate the city and utility reviews before construction:

  1. Ask Costa Mesa Planning to identify the zoning district and review the proposed use, lot standards and layout for zoning compliance.1211
  2. Discuss sewer service and sewer-plan approval with Costa Mesa Sanitary District, including any new or reconfigured sewer lateral.416
  3. Submit building plans and obtain the required building permit through Costa Mesa Building Safety’s TESSA route before construction.21
  4. Ask Costa Mesa Engineering Development Review about work in the public right-of-way; that office issues the corresponding work permits.20
  5. If a well is proposed, contact Orange County Environmental Health about the well permit before construction.8

For land outside Costa Mesa city limits, use the Orange County guide for the county’s unincorporated-area building-permit answer.21

Watch-outs

  • Costa Mesa’s 150-square-foot minimum concerns qualifying efficiency ADUs, not every primary dwelling or a wheeled tiny home.6
  • A Costa Mesa building permit does not replace CMSD sewer-plan approval and fee payment for covered projects.14
  • We could not confirm Costa Mesa’s certificate-of-occupancy or temporary-camping requirements; ask Building Safety about occupancy approval and Planning about camping before arranging a move-in.211

Sources

  1. Do I need a building permit for my project? (California statewide rule), quoted and re-checked
  2. Costa Mesa Building Safety Division (costamesaca.gov)
  3. Chapter II: Zoning Districts Established (Costa Mesa), quoted and re-checked
  4. Sewer Permits & Plan Requirements (Costa Mesa), quoted and re-checked
  5. hcd.ca.gov (California statewide rule), quoted and re-checked
  6. ecode360.com (Costa Mesa), quoted and re-checked
  7. California Business and Professions Code Section 7044 (California statewide rule), quoted and re-checked
  8. Orange County Environmental Health Well Permitting (ochealthinfo.com)
  9. Chapter I: In General (Costa Mesa), quoted and re-checked
  10. ecode360.com (Costa Mesa), quoted and re-checked
  11. Costa Mesa Planning Division (costamesaca.gov)
  12. Chapter II: Zoning Districts Established (Costa Mesa), quoted and re-checked
  13. Article 1: Residential Districts (Costa Mesa), quoted and re-checked
  14. Article 1: Residential Districts (Costa Mesa), quoted and re-checked
  15. Article 1: Residential Districts (Costa Mesa), quoted and re-checked
  16. Costa Mesa Sanitary District (costamesaca.gov)
  17. Water Quality Control Policy for Siting, Design, Operation and Maintenance of Onsite Wastewater Treatment Systems (OWTS Policy) (California statewide rule), quoted and re-checked
  18. Title 17: Trailers and Trailer Parks (Costa Mesa), quoted and re-checked
  19. Information Bulletin 2016-01: Tiny Homes (California statewide rule), quoted and re-checked
  20. Costa Mesa Engineering Development Review (costamesaca.gov)
  21. Building Permit Information (2026 county census)

Written October 11, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for Costa Mesa

Costa Mesa’s own rules

  • Building code adoptedAdopted

    All territory of Costa Mesa city, subject to stated exceptions and state-law supremacy.

    • The city adopts the 2025 California Building, Residential, Fire, Green Building Standards, Existing Building, Wildland-Urban Interface, Plumbing, Mechanical, Electrical, Energy, Property Maintenance, and related codes.
    • The Orange County Grading and Excavation Code is also adopted with modifications.
    • State regulations prevail where they differ from the adopted construction codes.
    • Fees do not take effect until adopted by city council resolution.
    “For the purpose of prescribing regulations for erecting, construction, enlargement, alteration, repair, improving, removal, conversion, demolition, occupancy, equipment use, height, and area of buildings and structures, the following construction codes subject to the modifications set forth in this chapter, are hereby adopted.”
  • Local zoningPresent

    Land inside Costa Mesa city limits.

    • The zoning districts and boundaries are shown on the official zoning map filed in the planning division.
    “In order to classify, regulate, restrict and separate the uses of land and buildings, regulate the height and bulk of buildings and the area of yards and other open spaces about buildings, and regulate population density, the following classes of zones are established:”
  • Zoning districtsPublished

    Costa Mesa zoning districts and official zoning-map administration.

    • The code lists R1, R2-MD, R2-HD, R3, AP, CL, C1, C2, C1-S, TC, P, I&R, I&R-S, MG, MP, PDR, PDC, PDI, MU, and other listed districts.
    • District boundaries are shown on the official zoning map filed in the planning division.
    “The zoning districts listed in section 13-20, zoning districts, and the boundaries of each, are shown on the official zoning map, filed in the planning division.”
  • Minimum dwelling sizeSpecified

    Accessory dwelling units in Costa Mesa.

    • This numeric minimum applies to ADUs and does not establish a universal minimum size for every primary dwelling.
    • ADUs may be efficiency units below 220 square feet only if at least 150 square feet and otherwise legally compliant.

    minimum ADU size: >= 150 square feet (Efficiency units may be below 220 square feet.)

    “ADUs may be efficiency units. Notwithstanding the general limitation on efficiency units being no smaller than 220 square feet, ADUs may also be less than 220 square feet, provided that they are no smaller than 150 square feet, and comply with all other legal requirements.”
  • Minimum lot sizeSpecified

    R1 Single-Family Residential District.

    • The R1 district is intended for single-family detached units.
    • Newly subdivided R1 lots also have minimum lot-area and lot-width requirements.

    minimum lot area: >= 6000 square feet

    “R1 Single-Family Residential District. This district is intended to promote the development of single-family detached units located on lots with a minimum lot size of 6,000 square feet, and a maximum density of 7.26 dwelling units per gross acre.”
    One more reviewed finding on this topic
    • Specified — R2-MD, R2-HD, and R3 residential districts.
      “R2-HD Multiple-Family Residential District, High Density. This district is intended to promote the development of multi-family rental as well as ownership dwelling units on lots with a minimum size of 12,000 square feet.”
  • Building heightSpecified

    Residential land uses in the R1 Single-Family Residential District.

    • The table also limits residential land uses to two stories.
    • Lofts meeting the stated definition are not counted as a story.

    maximum stories: <= 2 stories (Defined lofts are excluded from story count) · maximum building height: <= 27 feet

    “Maximum Number of Stories & Building Height | 2 stories/27 feet for residential land uses.”
  • Manufactured homesLimited

    Manufactured/mobile-home parks inside Costa Mesa city limits.

    • Mobile-home parks are subject to Title 13 zoning regulations.
    • A conditional-use permit is required for trailer or mobile-home parks.
    “Trailer parks or mobile home parks are subject to the zoning regulations contained in Title 13 of this Code and require the approval of a conditional use permit.”
  • Permit feesVariable (with conditions)

    Permits and services under Costa Mesa construction codes.

    • Fees are collected by the development services director or designee.
    • A supplemental fee may be charged when prescribed fees do not cover service costs.
    • Construction-code fees do not take effect until adopted by city council resolution.
    “Notwithstanding the provisions of the above-referenced construction codes, all fees for services provided pursuant to the construction codes shall not take effect until a resolution for such fees is adopted by the city council pursuant to California Government Code sections 66016 and 66020.”

Rules another office applies inside Costa Mesa

Costa Mesa does not set these itself; the county, a health district or the state does, and they apply to every address inside its limits.

  • Mandatory utility hookupSewer (with conditions)

    New structures, plumbing fixtures, and improvements inside Costa Mesa served by the Costa Mesa Sanitary District.

    • CMSD wastewater service covers the city of Costa Mesa.
    • Sewer plan approval and fee payment are required before construction of any new structures, plumbing fixtures, or other improvements.
    • Projects involving new or reconfigured sewer laterals require a sewer plan.
    • The source does not establish a general public-water connection-distance rule.
    “Sewer plan approval and fee payment are required prior to construction of any new structures, plumbing fixtures, or other improvements.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Costa Mesa or Orange County directly.

  • Owner-builder exemption — Owner-builders performing construction inside Costa Mesa city limits.
  • Inspections — Building work inside Costa Mesa city limits.
  • Certificate of occupancy — Occupancy of buildings inside Costa Mesa city limits.
  • Camping on your land — Temporary camping on private land inside Costa Mesa city limits.
  • Tiny homes — Tiny-home occupancy inside Costa Mesa city limits.
6 more unanswered
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Agricultural exemption
  • Short-term rentals

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Costa Mesa publishes no rule on the point, not that none exists. Orange County’s page lists the county offices to call.

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