Bolthole Index

Contra Costa County, California

Building permits, zoning and septic rules in Lafayette, California

Inside Lafayette, California (Contra Costa County), the city's Planning & Building Department administers the city zoning code, while the city contracts with Contra Costa County for building inspection services.1 Building permit applications go to the Contra Costa County Building Department in Martinez.2 Septic permits are separate again and come from Contra Costa Health's Environmental Health Division.3

At a glance

Building permit
Required for building work; applications go to the Contra Costa County Building Department42
Zoning
City of Lafayette administers its own zoning code1
Septic
Contra Costa Environmental Health approves septic plans3
RV living
Using any vehicle for living or sleeping is prohibited in city limits5
Accessory dwelling
State law requires ministerial review; city rules and percolation-test requirements apply to septic-served units67
Front setback (R-6)
At least 20 feet8

Who to call

Planning & zoning

City of Lafayette Planning Department

Zoning code administration, planning and design review applications inside Lafayette

(925) 284-1976

[email protected]

3675 Mt. Diablo Boulevard #210, Lafayette, CA 94549

Building permits

Contra Costa County Building Department (serves Lafayette by contract)

Building permit applications and building inspection for projects inside Lafayette, under the city's contract with the county

(925) 655-2700

[email protected]

30 Muir Road, Martinez, CA 94553

Septic permits

Contra Costa Health - Environmental Health Division

Septic construction permits, well permits, and site and soil evaluations through the Land Use Program

925-608-5500

2120 Diamond Boulevard, Suite 100, Concord, CA 94520

Contact details are copied from each office’s official page and were checked against it on October 10, 2026.

Off-grid gear

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

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Do you need a building permit in Lafayette, California?

Yes. California requires a permit from the building official before any building or structure is erected, enlarged, altered, repaired, moved or demolished.4 Lafayette adds a specific rule for solar: a building permit is required to install a solar energy system.9

Two more city permits catch buyers by surprise. Work in the public right-of-way, including a driveway culvert, requires an encroachment permit.10 We could not confirm the city's owner-builder rules, so ask the building department before you plan to act as your own contractor.2

Who issues building permits in Lafayette, and how do you reach them?

Lafayette does not run its own building inspection staff: the city contracts with Contra Costa County for building inspection services.2 Building permit applications are submitted to the Contra Costa County Building Department at 30 Muir Road in Martinez, reachable at (925) 655-2700 or [email protected].2

Planning and zoning questions stay at City Hall: the City of Lafayette Planning Department is at 3675 Mt. Diablo Boulevard #210, (925) 284-1976, [email protected].1

Does Lafayette have zoning, and what does it mean for setbacks and RVs?

Lafayette has its own zoning code, administered by the city's Planning & Building Department; Contra Costa County's unincorporated-area zoning does not apply inside city limits.111 In the R-6 single-family district, any structure needs a front-yard setback of at least 20 feet.8

RV living is not an option on a Lafayette lot: city code states that no person shall use any vehicle for living or sleeping purposes.5 State law also says RVs are not intended as permanent dwellings.12 We could not confirm the city's tiny-home rules, so ask the Planning Department.1

How do septic permits work in Lafayette?

Septic permits do not come from the city. In Contra Costa County, Environmental Health serves properties with septic systems and wells, and projects with septic systems require Environmental Health approved plans at application submittal.3 Most in-town Lafayette lots are likely on public sewer, but we could not confirm septic rules inside city limits, so ask Environmental Health before assuming sewer is available.13

An accessory dwelling unit that connects to an onsite wastewater system needs a percolation test completed within the last five years with the application.7 Contra Costa soils rarely suit conventional drain fields: only about 0.5% rate without severe limits.14

Can you build an accessory dwelling unit in Lafayette?

California requires local agencies to consider and approve accessory dwelling unit applications ministerially, without discretionary review or a hearing.6 The agency must tell the applicant whether the application is complete within 15 business days.6

In Lafayette, lot coverage limits for the largest ADU class (Class C) are 50 percent in the D-1 district, 35 percent in M-R-A and 25 percent in M-R-B.15 Ask the Planning Department which district and ADU class fit your parcel.1

Building a home in Lafayette: the steps, in order

  1. Confirm the parcel's zoning district and setbacks with the City of Lafayette Planning Department.1
  2. If the lot is not on public sewer, get Environmental Health approved septic plans before applying.3
  3. Submit the building permit application to the Contra Costa County Building Department.2
  4. Get an encroachment permit for any driveway or culvert work in the public right-of-way.10
  5. Call for inspections through the county building department during construction.2

What should you check before you buy land in Lafayette?

Severe drought hits about 40.4% of years in Contra Costa County, so confirm water service before you buy.16 A parcel in a FEMA special flood hazard area needs a floodplain permit from the county before improvements are built.17

Contra Costa County's effective property tax rate is 0.8%, but check the parcel's actual bill.18

Watch-outs

  • Do not start from Contra Costa County's unincorporated-area planning counter for zoning: inside Lafayette, zoning questions go to the City of Lafayette Planning Department.1
  • We could not confirm Lafayette's rules for tiny homes, private wells, owner-builders or short-term rentals; ask the Planning Department.1

Sources

  1. City of Lafayette Planning Department (lovelafayette.org)
  2. Contra Costa County Building Department (serves Lafayette by contract) (lovelafayette.org)
  3. contracosta.ca.gov, quoted and re-checked
  4. Do I need a building permit for my project? (California statewide rule), quoted and re-checked
  5. Lafayette Municipal Code § 6-2304, Prohibited activities (Lafayette), quoted and re-checked
  6. Accessory Dwelling Unit Handbook March 2026 (California statewide rule), quoted and re-checked
  7. Lafayette Municipal Code § 6-563, General ADU and JADU requirements (Lafayette), quoted and re-checked
  8. Lafayette Municipal Code § 6-710, R-6 setback (Lafayette), quoted and re-checked
  9. Lafayette Municipal Code § 3-1001, Building permit required (Lafayette), quoted and re-checked
  10. Lafayette Municipal Code § 8-2003, Driveway culverts (Lafayette), quoted and re-checked
  11. Planning and Zoning, quoted and re-checked
  12. hcd.ca.gov (California statewide rule), quoted and re-checked
  13. Contra Costa Health - Environmental Health Division (cchealth.org)
  14. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  15. Lafayette Municipal Code § 6-566, Class C ADUs (Lafayette), quoted and re-checked
  16. Share of years in severe drought: Bolthole Index county data
  17. FEMA Floodplain Management Program, quoted and re-checked
  18. Effective property tax rate: Bolthole Index county data

Written October 10, 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 Lafayette

Lafayette’s own rules

  • Building permitLimited

    Installation of a solar energy system in Lafayette city limits.

    • The ordinance defines solar energy system by Civil Code Section 801.5.
    “A building permit is required to install a solar energy system.”
  • SetbacksSpecified

    Structures in Lafayette's R-6 single-family residential district.

    • On corner lots, the principal frontage remains 20 feet and the other frontage is 15 feet.

    front-yard setback: >= 20 feet (Corner lot's other setback is at least 15 feet.)

    “There shall be a setback (front yard) of at least 20 feet for any structure in the R-6 district”
  • Lot coverageDistrict specific (with conditions)

    Class C ADUs in D-1, M-R-A, and M-R-B districts.

    • The limits are subject to § 6-566(a)(3), which prevents certain standards from requiring an ADU smaller than 800 square feet.

    D-1 lot coverage: <= 50 percent (Class C ADU total lot coverage.) · M-R-A lot coverage: <= 35 percent (Class C ADU total lot coverage.) · M-R-B lot coverage: <= 25 percent (Class C ADU total lot coverage.)

    “D-1 district: 50 percent. (2) M-R-A district: 35 percent. (3) M-R-B district: 25 percent.”
  • Living in an RVProhibited

    Use of a vehicle, including a recreational vehicle, for living or sleeping in Lafayette city limits.

    • Registered, operable recreational vehicles may be kept on occupied lots only if owner-registered, screened, outside the front yard, and not used for living or sleeping.
    “No person shall use any vehicle for living or sleeping purposes.”
  • Camping on your landLimited

    City parks and sports fields in Lafayette.

    • Camping may be allowed only in Lafayette Community Park pursuant to a director-issued permit under Chapter 11-3.
    “Camping may be allowed in the Lafayette Community Park pursuant to a permit issued by the director”
  • Off-grid sanitationLimited

    ADUs and JADUs that will connect to an onsite wastewater-treatment system in Lafayette city limits.

    • The application must include a percolation test completed within five years, or within ten years if recertified.

    percolation test age: <= 5 years (May be up to ten years if recertified.)

    “the owner must include with the application a percolation test completed within the last five years”
  • Driveway accessRequired

    Driveway-culvert work in a public right-of-way in Lafayette city limits.

    • The responsible person must maintain the culvert to city-engineer standards; the requirement is limited to work in the public right-of-way.
    “maintain the driveway culvert in a hydraulically adequate condition [...] Work in the public right-of-way requires an encroachment permit.”

Still unanswered

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

  • Owner-builder exemption — Residential work in Lafayette city limits.
  • Inspections — Residential construction in Lafayette city limits.
  • Tiny homes — Tiny-home occupancy in Lafayette city limits.
  • Who permits septic — Onsite wastewater systems inside Lafayette city limits.
  • Septic permit — Onsite wastewater systems inside Lafayette city limits.
5 more unanswered
  • Septic inspection
  • Well permit
  • Mandatory utility hookup
  • 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 Lafayette publishes no rule on the point, not that none exists. Contra Costa County’s page lists the county offices to call.

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