PAGE

California Building Codes, Permits and Contractor Rules

Here’s every rule from our 50-state guides for California on one page: the residential building code, frost depth, retaining wall permits, the 811 dig law, drainage law, contractor licensing, deposit limits, mechanics lien deadlines, workers’ comp, planting zones and frost dates. Each section links the official source and the full 50-state comparison.

California at a glance

Building code: 2024 IRC (statewide minimum)
Frost depth: Set by your local building department
811 notice: At least 2 working days, and not more than 14 calendar days, before excavating (day of notice not counted)
Contractors: State license required
Deposits: 10% or $1,000, whichever is less
Liens: 90 days after completion (60/30 if NOC)
Workers’ comp: 1+ (all licensees from 2028)
Drainage rule: Civil law (natural flow)
Planting zones: 4b to 11a

Topic	California	Compare
Residential building code	2024 IRC (statewide minimum)	All states
Frost line depth	Set by your local building department	All states
Retaining wall permit	Set locally. CRC Chapter 1 Division II (incl. R105.2) is not adopted by HCD except where indicated, so cities and counties adopt it, often with amendments.	All states
811 notice before digging	At least 2 working days, and not more than 14 calendar days, before excavating (day of notice not counted)	All states
Contractor license	State license required	All states
Deposit limit	10% or $1,000, whichever is less	All states
Right to cancel	3 bus. days (5 if 65+), sales at home	All states
Lien filing deadline	90 days after completion (60/30 if NOC)	All states
Workers’ comp required	1+ (all licensees from 2028)	All states
Drainage between neighbors	Civil law (natural flow)	All states
Planting zones (2023 USDA)	4b to 11a	All states
Frost dates (NOAA)	Last frost mid-Jan (Fresno) to mid-May (Mount Shasta); first frost early Oct (Mount Shasta) to mid-Dec (Fresno); no freeze in a typical year at the Los Angeles airport (LAX) station	All states

Summary for California. Details, exceptions and official sources are in each section below.

California residential building code

Code: 2025 California Residential Code (California Code of Regulations Title 24, Part 2.5), based on the 2024 International Residential Code
How it applies: Statewide minimum, local amendments allowed
In effect since: January 1, 2026
Code agency: California Building Standards Commission (with the Department of Housing and Community Development for residential provisions)
Who enforces it: Cities and counties enforce the code and may adopt stricter local amendments.
Good to know: California's residential code is rewritten every three years and the current 2025 edition is based on the 2024 IRC. Many cities add their own stricter rules, so check with your local building department.

Compare building codes in all 50 states

Frost line depth in California

Who sets it: Local building department
Local examples: Town of Truckee: 18 in. below 7,000 ft elevation; 24 in. above 7,000 ft
Town of Mammoth Lakes: 24 in.
Good to know: The examples are Sierra mountain towns. For Los Angeles, San Francisco, Sacramento or San Diego, check with the local building department.

Frost line depth in every state

Retaining wall permits in California

Permit exemption: Set locally. CRC Chapter 1 Division II (incl. R105.2) is not adopted by HCD except where indicated, so cities and counties adopt it, often with amendments. The CRC's R105.2 text exempts walls not over 4 ft from bottom of footing to top of wall, unless supporting a surcharge.
Who decides: Your city or county building department decides, and many amend R105.2 locally.
Good to know: The 2025 California Residential Code took effect Jan. 1, 2026. Many cities and counties amend the 4 ft exemption, so check with your local building department.

Retaining wall permit rules in every state

811 dig law in California

One-call center: USA North 811 (Underground Service Alert of Northern California and Nevada) / DigAlert (Underground Service Alert of Southern California)
Notice before digging: At least 2 working days, and not more than 14 calendar days, before excavating (day of notice not counted)
Ticket good for: 28 days from issuance; renew by the end of the 28th day
Hand-dig zone: 24 in. on each side of the field marking (single mark treated as centerline)
Homeowners: Partial exemption. Gov. Code 4216.8 excludes (a) owners who hire a licensed contractor for non-permit work on their property and (b) a residential owner who is not a licensed contractor doing non-permit excavation to improve their principal residence; such owners 'may' contact the center if the property is known to contain subsurface lines. 'Excavation' itself has no hand-tool or depth exclusion; anyone else, including any permitted work, must call.
The law: Cal. Gov. Code §§ 4216-4216.24
Good to know: Both regional centers urge everyone to call, even owners the law exempts. A working day is Monday to Friday, 7 a.m. to 5 p.m., not counting holidays.

811 dig laws in every state

Drainage law and stormwater permits in California

Rule: Civil law (natural flow)
The rule: Modified civil law with a reasonableness test: neither the upper nor the lower owner may act unreasonably, and each must take reasonable care to avoid injuring the other through surface water; if both act reasonably, the upper owner who changed the natural drainage generally bears the loss.
Leading case: Keys v. Romley. 64 Cal. 2d 396 (1966); reaffirmed and extended in Locklin v. City of Lafayette, 7 Cal. 4th 327 (1994)
What it means for your yard: If you regrade, add downspouts or build a patio, a court will ask whether you acted reasonably and whether your neighbor did too. Unreasonable changes that send water onto a neighbor can make you liable, and if both of you acted reasonably, the owner who changed the natural drainage usually bears the loss.
Construction stormwater permit: State Water Resources Control Board and the nine Regional Water Quality Control Boards: 1 acre or more of disturbance (or less than 1 acre if part of a larger common plan totaling 1 acre or more): Construction Stormwater General Permit, Order WQ 2022-0057-DWQ
State rules below 1 acre: No statewide rule below the 1-acre permit found; check your county and town.
Local rules: California cities and counties commonly require grading permits and erosion control plans for residential projects well under 1 acre; check the local building or public works department.
Good to know: California courts judge drainage disputes by asking whether each neighbor acted reasonably; if both did, the one who changed the natural drainage usually bears the loss. Many cities and counties require a grading permit for jobs far smaller than the state's 1-acre stormwater permit threshold.

Drainage laws in every state

Contractor licensing in California

Statewide rule: License
Agency: Contractors State License Board (CSLB)
Who needs it: Anyone contracting for jobs of $1,000 or more, or any work requiring a permit, needs a CSLB license; unlicensed minor-work operators cannot employ anyone on the job.
When it applies: $1,000 or more (labor + materials), or any job that needs a permit
Check a contractor: Official lookup
Good to know: AB 2622 raised the minor-work exemption from $500 to $1,000 on Jan. 1, 2025. Unlicensed workers may advertise jobs under $1,000 only if the ad says they are not licensed.

Contractor license requirements in every state

Contractor deposits and your right to cancel in California

Deposit limit: Down payment may not exceed $1,000 or 10% of the contract price (excluding finance charges), whichever is less, on home improvement and swimming pool contracts, and the contractor may not request or accept payments that exceed the value of work performed (Bus. & Prof. Code § 7159.5(a)(3), (a)(5)); violating the down payment limit is a misdemeanor (§ 7159.5(b)). The Contractors State License Board says there is no exception for special-order materials; the only exception is for contractors with a blanket performance and payment bond on file with the Board.
Who it covers: Home improvement and swimming pool contracts, which the Contractors State License Board says covers almost any work at a residence, including building an accessory dwelling unit (ADU) (Bus. & Prof. Code §§ 7151, 7151.2, 7159, 7159.5).
Right to cancel: Home solicitation contracts (signed somewhere other than the contractor's place of business): 3 business days to cancel; 5 business days if the buyer is a senior citizen (65 or older, per the Contractors State License Board); 7 business days for repair or restoration of a disaster-damaged home (Civil Code § 1689.6; notice required by Bus. & Prof. Code § 7159). Contracts negotiated at the contractor's place of business are not covered.
Written contract: Required for home improvement projects over $500 (labor and materials combined). Must include the contractor's license information, description of work, contract price, down payment, a schedule of progress payments, start and completion dates, the mechanics lien warning, and the notice of the right to cancel (Bus. & Prof. Code § 7159).
Other protections: Progress payments may not exceed the value of work performed, and the down payment cap applies to swimming pools too (Bus. & Prof. Code § 7159.5).
The law: Cal. Bus. & Prof. Code §§ 7159, 7159.5; Cal. Civil Code §§ 1689.5–1689.14
Good to know: In California, a down payment of more than $1,000, or more than 10% on a smaller job, is illegal on home improvement and pool contracts, ADUs included. If you are 65 or older, you have five business days instead of three to cancel a contract signed at your home.

Contractor deposit limits in every state

Mechanics lien deadlines in California

Lien deadline (prime): Record the claim of lien after completing the direct contract and before the earlier of 90 days after completion of the work of improvement or 60 days after the owner records a notice of completion or cessation (Cal. Civ. Code § 8412).
Lien deadline (sub/supplier): Record after ceasing work and before the earlier of 90 days after completion of the work of improvement or 30 days after the owner records a notice of completion or cessation (Cal. Civ. Code § 8414).
Preliminary notice (sub/supplier): Required. Preliminary notice to the owner, the direct contractor and any construction lender within 20 days after first furnishing work; it is a prerequisite to a valid lien (laborers exempt). A late notice covers only work in the 20 days before it was given and afterward (Cal. Civ. Code §§ 8200, 8204).
Notice of intent: Not required.
Enforce within: Action to enforce within 90 days after recording the claim of lien, or the lien expires; a recorded credit agreement can extend this to 90 days after the credit ends, but not past 1 year after completion (Cal. Civ. Code § 8460).
Homeowner rules: Home improvement contracts over $500 must carry the Mechanics Lien Warning, which tells owners that unpaid subs and suppliers can lien even if the owner paid the contractor in full, and suggests joint checks and lien releases (Bus. & Prof. Code § 7159(e)(4)).
The law: Cal. Civil Code, Div. 4, Part 6 (Works of Improvement), § 8000 et seq.; Bus. & Prof. Code § 7159
Good to know: California subcontractors and suppliers must send a preliminary notice within 20 days of starting, and a homeowner's recorded notice of completion cuts their lien window to 30 days (60 for the general contractor).

Mechanics lien deadlines in every state

Workers' comp requirements in California

Who must carry it: Every employer with 1 or more employees must carry coverage (California DIR). For CSLB-licensed contractors: a licensee with no employees may file an exemption, except C-8 Concrete, C-20 HVAC, C-22 Asbestos Abatement, C-39 Roofing and C-61/D-49 Tree Service, which must carry comp whether or not they have employees (CSLB). Under SB 1455 (2024), all licensees must carry comp regardless of employees starting January 1, 2028 (CSLB industry bulletin).
Owners and officers: A licensed contractor with no employees can file an exemption with CSLB, but not if it holds one of the five mandatory classifications or its license is qualified by a Responsible Managing Employee; if an exempt contractor hires someone, proof of coverage must reach CSLB within 90 days (CSLB). An officer or director who is the sole shareholder of a private corporation is excluded; officers or directors owning at least 10% of the stock, general partners and LLC managing members can waive coverage in writing to their insurer (Lab. Code § 3352(a)(16)-(17)).
Subcontractors: Anyone doing work that requires a contractor's license, or working for someone required to hold one, is presumed to be an employee rather than an independent contractor, and must hold a valid license to be treated as independent (Lab. Code § 2750.5). Hiring an unlicensed 'sub' can therefore leave you responsible for that sub and its crew.
Homeowners: CSLB warns that a homeowner may be liable for medical bills if an uninsured worker is hurt on the property, and that a homeowner's insurance policy might not apply if the worker wasn't licensed (CSLB). Hire licensed, insured contractors.
Penalties: CSLB suspends a contractor's license if required comp coverage lapses, and work done while suspended counts as unlicensed (CSLB). The Labor Commissioner can cite an uninsured employer $1,500 per uncovered employee and issue a stop order halting work until coverage is obtained; violating a stop order can bring penalties up to $10,000 and misdemeanor charges (DIR Labor Commissioner).
The law: Cal. Lab. Code § 3700 et seq.; §§ 2750.5, 3352; Bus. & Prof. Code § 7125
State agency: California Department of Industrial Relations (DIR), Division of Workers' Compensation; Contractors State License Board (CSLB)
Good to know: California requires coverage with even one employee. Concrete, HVAC, asbestos, roofing and tree service licensees must carry it even with no employees, and every licensed contractor must carry it starting January 1, 2028.

Workers' comp requirements in every state

Planting zones in California

2023 USDA zones: 4b to 11a
Coldest-night range: −25°F to 45°F
Warmest area: Parts of the San Diego area, including downtown San Diego
Example cities: Los Angeles: 10b, San Francisco: 10b, San Diego: 11a, Sacramento: 9b
Good to know: California covers more zones than almost any other state. Los Angeles and San Francisco are 10b and downtown San Diego is 11a, but zones drop quickly with elevation, so mountain gardeners should look up their own ZIP code.

Planting zones in every state

Frost dates in California

Station	Last spring frost	First fall frost	Frost-free days
Los Angeles Southern California coast (LAX airport station)	No freeze in a typical year		365
Sacramento Northern Central Valley	February 2	December 2	301
Fresno San Joaquin Valley	January 14	December 14	337
Mount Shasta Northern mountains	May 15	October 6	143

Typical range: Last frost mid-Jan (Fresno) to mid-May (Mount Shasta); first frost early Oct (Mount Shasta) to mid-Dec (Fresno); no freeze in a typical year at the Los Angeles airport (LAX) station
Good to know: These are typical (50%) dates from NOAA's 1991–2020 climate normals, so about half of years still bring a 32°F night after the listed spring date. In California, the last spring frost at the stations listed ranges from mid-January around Fresno to mid-May around Mount Shasta; NOAA's coastal Los Angeles airport station usually sees no freeze at all.

Frost dates in every state

Frequently Asked Questions

What building code does California use?

2025 California Residential Code (California Code of Regulations Title 24, Part 2.5), based on the 2024 International Residential Code. It applies as follows: statewide minimum, local amendments allowed. Your local building department can confirm the edition and amendments for your address.

How deep is the frost line in California?

Frost depth is set by local building departments. Footings for houses, additions and attached decks go below it.

How much can a contractor ask for up front in California?

Down payment may not exceed $1,000 or 10% of the contract price (excluding finance charges), whichever is less, on home improvement and swimming pool contracts, and the contractor may not request or accept payments that exceed the value of work performed (Bus. & Prof. Code § 7159.5(a)(3), (a)(5)); violating the down payment limit is a misdemeanor (§ 7159.5(b)). The Contractors State License Board says there is no exception for special-order materials; the only exception is for contractors with a blanket performance and payment bond on file with the Board. Cancel rights: Home solicitation contracts (signed somewhere other than the contractor’s place of business): 3 business days to cancel; 5 business days if the buyer is a senior citizen (65 or older, per the Contractors State License Board); 7 business days for repair or restoration of a disaster-damaged home (Civil Code § 1689.6; notice required by Bus. & Prof. Code § 7159). Contracts negotiated at the contractor’s place of business are not covered.

How long does a contractor have to file a mechanics lien in California?

Record the claim of lien after completing the direct contract and before the earlier of 90 days after completion of the work of improvement or 60 days after the owner records a notice of completion or cessation (Cal. Civ. Code § 8412). Subcontractors and suppliers may have different notice rules; see the section above.

What planting zone is California?

On the 2023 USDA map, California runs from zone 4b to 11a. Examples: Los Angeles 10b, San Francisco 10b, San Diego 11a. Enter your ZIP on the USDA map for your exact zone.

Do contractors need workers' comp in California?

Every employer with 1 or more employees must carry coverage (California DIR). For CSLB-licensed contractors: a licensee with no employees may file an exemption, except C-8 Concrete, C-20 HVAC, C-22 Asbestos Abatement, C-39 Roofing and C-61/D-49 Tree Service, which must carry comp whether or not they have employees (CSLB). Under SB 1455 (2024), all licensees must carry comp regardless of employees starting January 1, 2028 (CSLB industry bulletin). Owner exemptions and subcontractor rules are in the workers’ comp section above.

When is the last frost in California?

At the NOAA stations we list: Last frost mid-Jan (Fresno) to mid-May (Mount Shasta); first frost early Oct (Mount Shasta) to mid-Dec (Fresno); no freeze in a typical year at the Los Angeles airport (LAX) station. These are typical (50%) dates from the 1991–2020 climate normals, so about half of years still bring a 32°F night after the spring date.

This page is general information, not legal or tax advice. Rules change; the agencies and statutes linked above have the final word.

California in each 50-state guide: Frost line depth · 811 dig laws · Retaining wall permits · Contractor licensing · Contractor deposit limits · Building codes · Planting zones · Mechanics lien deadlines · Workers' comp · Frost dates · Drainage laws · Noxious weed laws · Rainfall and snowfall · Landscaper pay · Pesticide applicator licensing · Landscaping sales tax · All state guides

Soil: California’s most common soils, state soil, and how much ground is wet, clayey or shallow to bedrock by county. California soil types

Last checked October 31 and November 1, 2026 against official state and local sources for this state. Rules change; your state agency or local building department has the final word. Spot something out of date? Email info@muthlerlandscaping.com and we’ll fix it.

Groundwork Design Co. · designed by builders

Plans drawn for California’s rules

Groundwork Design Co. draws patios, walls, decks and planting plans to scale for any U.S. home, with the layout, sizes and materials any local contractor can price. Single-space plans start at $349; a framing and footing sheet for decks and porches is a $350 add-on.

See design plans See sample plans

Using this guide? Link to it or cite it. It’s free to use with a link back, and we keep it updated against official sources.

<a href="https://muthlerlandscaping.com/state-guides/california/">California Building Codes, Permits and Contractor Rules</a> (Muthler Landscaping & Construction)

Cite as: Muthler Landscaping & Construction, “California Building Codes, Permits and Contractor Rules,” https://muthlerlandscaping.com/state-guides/california/ (last checked November 12, 2026).

Get an email when your state’s rules change

We re-check every entry against official sources. Tell us your state and we’ll email you when something changes.