Costa Mesa Municipal Code § 5-1 Construction codes adopted

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. The California Building Code, 2025 Edition, based on the 2024 International Building Code as published by the International Code Council, including Chapter 1, Division II. The California Residential Code, 2025 Edition, based on the 2024 International Residential Codes published by the International Code Council, including Chapter 1, Division II; including Appendix AX Swimming Pool Safety Act. The 2025 California Fire Code based on the 2024 International Fire Code. The 2025 California Green Building Standards Code. The 2025 Existing Building Code, based on the 2024 International Existing Building Code. The 2025 California Wildland-Urban Interface Code, based on the 2024 International Wildland- Urban Interface Code. The 2021 International Swimming Pool & Spa Code. The California Plumbing Code, 2025 Edition, based on the 2024 Uniform Plumbing Code as published by the International Association of Plumbing and Mechanical Officials. The California Mechanical Code, 2025 Edition, based on the 2024 Uniform Mechanical Code as published by the International Association of Plumbing and Mechanical Officials. The California Electrical Code, 2025 Edition, based on the 2023 National Electrical Code as published by the National Fire Protection Association. The California Energy Code, 2025 Edition, based on the 2024 International Energy Conservation Code. The International Property Maintenance Code, 2024 Edition, as published by the International Code Council. The Uniform Code for the Abatement of Dangerous Buildings, 2021 Edition, as published by the International Code Council. For the purpose of prescribing regulations for grading and excavation, the Orange County Grading and Excavation Code will be hereby adopted, in addition, to Appendix "J" of the 2025 California Building Code and the more restrictive provisions of the two will prevail. The provisions of these Construction Codes as amended by this chapter shall constitute the Building Regulations of the City of Costa Mesa. Where the California Code of Regulations and State Building Standards Code of Regulations differ from any sections of the Construction Codes, State regulations shall prevail over the Construction Codes.

One copy of all the above codes and standards therefore are on file in the office of the building official pursuant to Health and Safety Code section 18942(d)(1) and are made available for public inspection.

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.

(Code 1960, § 8100; Ord. No. 62-4, 3-5-62; Ord. No. 65-20, 7-19-65; Ord. No. 68-44, 12-2-68; Ord. No. 68-45, 12-2-68; Ord. No. 71-14, § 2, 6-21-71; Ord. No. 75-3, § 2, 1-4-75; Ord. No. 82-13, § 2(1), 9-7-82; Ord. No. 87-22, § 2(1), 11-2-87; Ord. No. 92-22, § 1, 12-21-92; Ord. No. 95-22, § 2, 1-2-96; Ord. No. 99-6, § 1, 6-7-99; Ord. No. 07-18, § 1, 10-16-07; Ord. No. 10-10, § 1, 9-21-10; Ord. No. 13-06, § 1, 11-19-13; Ord. No. 16-14, § 1, 12-6-16; Ord. No. 19-18, § 1, 11-19-19; Ord. No. 22-07, § 1, 11-2-22; Ord. 2025-08, 11/18/2025)

§ 5-1.1. Amendments to the 2025 California Building Code.¶

The following amendments to the California Building Code shall apply in the city:

(a) Administration. Division II of Chapter 1, entitled "Scope and Administration", is applicable in the city.

(b) Revision. Insert City of Costa Mesa into the text as the name of jurisdiction in Section 101.1.

(c) Section 101.4 is deleted in its entirety (including sections 101.4.1, 101.4.2, 101.4.3, 101.4.4, 101.4.5, 101.4.6 and 101.4.7), and replaced with the following:

101.4. Referenced Codes. The California Codes listed in Section 5-1 of this Ordinance shall be considered part of the requirements of this code to the extent of each such reference.

(d) Section 105.2 is revised by amending exception 2, 9, and adding 14 as follows:

Wood, Steel, Vinyl, or Iron fences not over 6 feet in height. Stucco, concrete, and masonry brick fences not over 3 feet high.
Prefabricated swimming pools accessory to a Group R-3 occupancy that are less than 18 inches (457.2 mm) deep, do not exceed 5,000 gallons (18,927.059 L) and are installed entirely above ground.
Decks not exceeding 200 square feet (18.58 m2) in area, that are not more than 30 inches (762 mm) above grade at any point, are not attached to a dwelling and do not serve the exit door required by Section R311.2.

(e) Board of Appeals. Section 113.3 is amended to provide as follows:

Board of Appeals, when used in the Building Standards Codes shall mean the City Planning Commission. The Board of Appeals is hereby established for each of the Building Standards Codes. Depending on the subject of the appeal, specialized expertise may be solicited for the purpose of providing input to the Appeals Board.

(f) Table 1505.1 is amended, by the deletion of Table 1505.1 and the addition of a new Table 1505.1 thereto, to read as follows:

TABLE 1505.1 a MINIMUM ROOF COVERING CLASSIFICATIONS TYPES OF CONSTRUCTION

IA	IB	IIA	IIB	IIIA	IIIB	IV	VA	VB
B	B	B	B	B	B	B	B	B

For SI: 1 foot = 304.8 mm, 1 square foot = 0.0929 m 2 .

a.	Unless otherwise required in accordance with Part 7, California Wildland Urban Interface Code (WUI)

(g) Section 1505.1.2 is amended to read as follows:

1505.1.2 Roof coverings within all other areas other than Fire Hazard Severity Zones or Wildland - Urban Interface (WUI). The entire roof covering of every existing structure where more than fifty 50 percent of the total roof area is replaced within any one-year period, the entire roof covering of every new structure, and any roof covering applied in the alteration, repair or replacement of the roof of every existing structure, shall be a fire-retardant roof covering that is at least Class B.

(h) Section 1505.4 is amended, by the deletion of the entire section.

(i) Section 1505.5 is amended, by the deletion of the entire section.

(j) Section 1807.1.6 is amended to read as follows:

1807.1.6 Prescriptive design of concrete and masonry foundation walls. Concrete and masonry foundation walls that are laterally supported at the top and bottom shall be permitted to be designed and constructed in accordance with this section. Prescriptive design of foundation walls shall not be used for structures assigned to Seismic Design Category D, E or F.

(Ord. No. 07-18, § 2, 10-16-07; Ord. No. 10-10, § 2, 9-21-10; Ord. No. 11-4, § 1, 3-15-11; Ord. No. 13-06, § 2, 11-19-13; Ord. No. 16-14, § 2, 12-6-16; Ord. No. 19-18, § 2, 11-19-19; Ord. No. 22-07, § 1, 11-2-22; Ord. 2025-08, 11/18/2025)

Exceptions & meaning →

§ 5-1.3. Amendments to the 2025 California Residential Code.¶

Pursuant to the Assembly Bill 130 (AB 130), effective from October 1, 2025, through June 1, 2031, no new amendments are proposed for to the California Residential Code. The existing amendments shall remain in effect as currently adopted.

(a) Amend item number 2" in section R105.2, Work exempt from permit, as follows:

Wood, Steel, Vinyl, or Iron fences not over 6 feet in height. Stucco, concrete, and masonry brick fences not over 3 feet high.

(b) Table R301.2, is revised to read as follows:

TABLE R301.2 CLIMATIC AND GEOGRAPHIC DESIGN CRITERIA

Ground Snow Load o	WIND DESIGN	WIND DESIGN	WIND DESIGN	WIND DESIGN	Seismic Design Category f	SUBJECT TO DAMAGE FROM	SUBJECT TO DAMAGE FROM	SUBJECT TO DAMAGE FROM	Ice Barrier Under-layment Required h	Flood Hazards g	Air Freeze Index i	Mean Annual Temp j
Ground Snow Load o	Speed d (mph)	Topographic Effects k	Special Wind Region l	Windbourne Debris Zone m	Seismic Design Category f	Weathering a	Frost Line Depth b	Termite c	Ice Barrier Under-layment Required h	Flood Hazards g	Air Freeze Index i	Mean Annual Temp j
Zero	95	No	No	No	D 2 or E	Negligible	No	Very Heavy	No	No	Zero	60
MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n	MANUAL J DESIGN CRITERIA n
Elevation	Altitude Correction Factor e	Coincident Wet Bulb	Coincident Wet Bulb	Indoor Winter Design Relative Humidity	Indoor Winter Design Relative Humidity	Indoor Winter Design Dry-Bulb Temperature	Indoor Winter Design Dry-Bulb Temperature	Indoor Winter Design Dry-Bulb Temperature	Outdoor Winter Design Dry-Bulb Temperature	Outdoor Winter Design Dry-Bulb Temperature	Heating Temperature Difference	Heating Temperature Difference
98	1.0	69	69	—	—	70	70	70	43	43	27	27
Latitude	Daily Range	Summer Design Grains	Summer Design Grains	Indoor Summer Design Relative Humidity	Indoor Summer Design Relative Humidity	Indoor Summer Design Dry-Bulb Temperature	Indoor Summer Design Dry-Bulb Temperature	Indoor Summer Design Dry-Bulb Temperature	Outdoor Summer Design Dry-Bulb Temperature	Outdoor Summer Design Dry-Bulb Temperature	Cooling Temperature Difference	Cooling Temperature Difference
34	Low	23	23	50% RH	50% RH	75	75	75	85	85	10	10

For SI: 1 pound per square foot = 0.0479 kPa, 1 mile per hour = 0.447 m/s.

a.	Where weathering requires a higher strength concrete or grade of masonry than necessary to satisfy the structural requirements of this code, the frost line depth strength required for weathering shall govern. The weathering column shall be filled in with the weathering Index, "negligible," "moderate" or "severe" for concrete as determined from Figure R301.2(1). The grade of masonry units shall be determined from ASTM C34, ASTM C55, ASTM C62, ASTM C73, ASTM C90, ASTM C129, ASTM C145, ASTM C216 or ASTM C652.
b.	Where the frost line depth requires deeper footings than indicated in Figure R403.1(1), the frost line depth strength required for weathering shall govern. The jurisdiction shall fill in the frost line depth column with the minimum depth of footing below finish grade.
c.	The jurisdiction shall fill in this part of the table to indicate the need for protection depending on whether there has been a history of local subterranean termite damage.
d.	The jurisdiction shall fill in this part of the table with the wind speed from the ultimate design wind speeds map [Figure R301.2(2)]. Wind exposure category shall be determined on a site-specific basis in accordance with Section R301.2.1.4.
e.	The jurisdiction shall fill in this section of the table to establish the design criteria using Table 10A from ACCA Manual J or established criteria determined by the jurisdiction.
f.	The jurisdiction shall fill in this part of the table with the seismic design category determined from Section R301.2.2.1.
g.	The jurisdiction shall fill in this part of the table with: the date of the jurisdiction's entry into the National Flood Insurance Program (date of adoption of the first code or ordinance for management of flood hazard areas); and the title and date of the currently effective Flood Insurance Study or other flood hazard study and maps adopted by the authority having jurisdiction, as amended.
h.	In accordance with Sections R905.1.2, R905.4.3.1, R905.5.3,1, R905.6.3.1, R905.7.3.1, and R905.8.3.1, where there has been a history of local damage from the effects of ice damming, the jurisdiction shall fill in this part at the table with "YES." Otherwise, the jurisdiction shall fill in this part of the table with "NO."
i.	The jurisdiction shall fill in this part of the table with the 100-year return period air freezing index (BF-days) from Figure R403.3(2) or from the 100-year (99 percent) value on the National Climatic Data Center data table "Air Freezing Index-USA Method (Base 32°F)."
j.	The jurisdiction shall fill in this part of the table with the mean annual temperature from the National Climatic Data Center data table "Air Freezing Index-USA Method (Base 32°F)."
k.	In accordance with Section R301.2.1.5, where there is local historical data documenting structural damage to buildings due to topographic wind speed-up effects, the jurisdiction shall fill in this part of the table with "YES." Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
l.	In accordance with Figure R301.2(2), where there is local historical data documenting unusual wind conditions, the jurisdiction shall fill in this part of the table with "YES" and identify any specific requirements, Otherwise, the jurisdiction shall indicate "NO" in this part of the table.
m.	In accordance with Section R301.2.1.2 the jurisdiction shall indicate the wind- borne debris wind zone(s). Otherwise, the jurisdiction shall indicate "NO" In this part of the table.
n.	The jurisdiction shall fill in these sections of the table to establish the design criteria using Table 1a or 1b from ACCA Manual J or established criteria determined by the jurisdiction.
o.	The jurisdiction shall fill in this section of the allowable stress design table using the Ground Snow Loads in Figure R301.2(3).

R902.1 Roofing covering materials. Roofs shall be covered with materials as set forth in Sections R904 and R905. A minimum Class A or B roofing shall be installed in areas designated by this section. Class A or B roofing required by this section to be listed shall be tested in accordance with UL 790 or ASTM E 108.

Exceptions:

Class A roof assemblies include those with coverings of brick, masonry and exposed concrete roof deck.
Class A roof assemblies also include ferrous or copper shingles or sheets, metal sheets and shingles, clay or concrete roof tile, or slate installed on noncombustible decks.
Class A roof assemblies include minimum 16 oz/ft2 copper sheets installed over combustible decks.

(d) Section R902.1.2 is amended by revising it to require a minimum Class B as follows:

R902.1.2 Roof coverings within all other areas. The entire roof covering of every existing structure where more than 50 percent of the total roof area is replaced within any one-year period, the entire roof covering of every new structure, and any roof covering applied in the alteration, repair or replacement of the roof of every existing structure, shall be a fire-retardant roof covering that is at least class B.

(e) Section R902.2, first paragraph is amended by revising it to allow only class A or B treated wood roofs as follows:

R902.2 Fire-retardant-treated shingles and shakes. Fire-retardant-treated wood shakes and shingles are wood shakes and shingles complying with UBC Standard 15-3 or 15-4 which are impregnated by the full-cell vacuum-pressure process with fire- retardant chemicals, and which have been qualified by UBC Standard 15-2 for use on Class A or B roofs.

Fire-retardant-treated wood shakes and shingles shall comply with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code section 13132.7(j). Each bundle shall bear labels from an ICBO accredited quality control agency identifying their roof-covering classification and indicating their compliance with ICC-ES EG107 and with the weathering requirements contained in Health and Safety Code section 13132.7(j).

Health and Safety Code section 13132.7(j) No wood roof covering materials shall be sold or applied in this state unless both of the following conditions are met:

The materials have been approved and listed by the State Fire Marshal as complying with the requirements of this section.
The materials have passed at least five years of the 10-year natural weathering test. The 10-year natural weathering test required by this subdivision shall be conducted in accordance with Standard 15-2 of the 1994 Edition of the Uniform Building Code at a testing facility recognized by the State Fire Marshal.

(Ord. No. 10-10, § 3, 9-21-10; Ord. No. 11-4, § 1, 3-15-11; Ord. No. 13-06, § 3, 11-19-13; Ord. No. 16-14, § 3, 12-6-16; Ord. No. 17-03, § 2, 2-7-17; Ord. No. 19-18, § 3, 11-19-19; Ord. No. 22-07, § 1, 2022; Ord. 2025-08, 11/18/2025)

Exceptions & meaning →

§ 5-1.4. Adoption of the Orange County Grading and Excavation Code.¶

Orange County Grading and Excavation Code adopted with modifications.

(Ord. No. 19-18, § 5.5, 11-19-19; Ord. 2025-08, 11/18/2025)

Exceptions & meaning →

§ 5-1.4.1. Amendments to the Orange County Grading and Excavation Code.¶

Article 8 of Title 7, Division 1 of the Codified Ordinances of the County of Orange, including the Grading Manual, is adopted in its entirety, except that section 7-1-805(i) and 7-1-805(l) are modified as follows:

Section 7-1-805(i). A fill less than one (1) foot in depth which: (1) is placed on a natural grade with a slope less steep than five horizontal to one vertical (5:1); (2) does not exceed twenty (20) cubic yards on any one lot; and (3) does not obstruct a drainage course. This does not exempt the project proponent from submitting a compaction report, to the Building Official, for review and approval, on the fill placed.

Section 7-1-805(I). A fill less than three (3) feet in depth for a landscape planter, which does not exceed twenty (20) cubic yards on any one lot and does not obstruct a drainage course.

(Ord. No. 19-18, § 5.5, 11-19-19; Ord. 2025-08, 11/18/2025)

Exceptions & meaning →