Zoning, building permits and septic rules in Simi Valley, California

At a glance

Zoning

City zoning under Title 9 of the Municipal Code¹

Building permit

Required before building, remodeling or adding to a building; issued by the city²

Septic

Ventura County Environmental Health does not cover city limits; start with the city building department³

Minimum lot size

Varies by district: one acre in RE, 20,000 sq ft in RVL⁴⁵

Camping in a yard

Infrequent only, no more than 3 consecutive days⁶

Living in an RV

State rules generally limit RV living to parks; the city's private-lot rule is unconfirmed⁷

Owner-builder

State exemption covers contractor licensing only, not permits⁸

Who to call

Contact details are copied from each office’s official page and were checked against it on October 16, 2026.

Does Simi Valley have zoning, and what does it mean for lot size and setbacks?

Yes. Simi Valley zones land inside city limits through Title 9, the Development Code, of its Municipal Code¹. The city's Planning Division administers the zoning ordinance and general plan⁹. Residential and open space districts include OS, RE, RVL, RL, RM, RMod, RH, RVH, MH, W and WP¹⁰.

Minimum lot size depends on the district. In the RE (Residential Estate) district the minimum lot area is one acre⁴. In the RVL district, which the code describes as semi-rural single-family with relatively large lots, the minimum is 20,000 square feet⁵. The same table lists 10,000 square feet for RL, 8,000 for RM, 5,000 for RMod-Single and 40 acres for OS⁵.

Setbacks are also district-specific; the RE district has a 20 ft front setback, and the code lists front and rear setbacks of 20 ft in the other residential districts, with reductions for planned developments and for freeway or open space adjacency¹¹. Primary structures are limited to 2 stories and 30 ft¹². Look up the district for a specific parcel with the Planning Division before you buy.

Do you need a building permit in Simi Valley, and who issues it?

Inside Simi Valley, construction permits must be obtained before constructing a new building, remodeling or adding to an existing building, and the city's Building and Safety Division issues them². Most buildings and structures must be designed by an architect or engineer registered with the State of California². For questions about plan review or permitting, call the Building and Safety Division at (805) 583-6723².

Ventura County's building department covers only unincorporated land, so its permit office is the wrong counter for a Simi Valley address¹³. We could not confirm which building code edition the city has adopted, or its permit fee schedule; ask Building and Safety.

California's owner-builder exemption removes the contractor-licensing requirement for an owner building on their own property, but it does not by itself exempt the work from local building permits or inspections⁸.

How do septic permits work inside Simi Valley?

Ventura County Environmental Health issues septic permits only in unincorporated Ventura County¹⁴. For a system inside city limits, the county tells owners to contact the appropriate city building department for septic permit information³. For a Simi Valley address, call the city's Building and Safety Division first at (805) 583-6723².

We could not confirm from an official page whether Simi Valley itself permits septic systems, or whether a given lot must connect to sewer, so ask the city before assuming either one. Statewide, septic systems fall under the State Water Board's onsite wastewater policy, with local agencies implementing it where approved¹⁵.

Soil matters too. Across Ventura County, only about 11% of soils are rated "not limited" for a conventional drain field, so a site evaluation or an engineered system is common¹⁶.

Can you live in an RV or tiny home in Simi Valley?

The city's rule on living in an RV on a private residential lot is unconfirmed; ask the Planning Division at (805) 583-6769⁹. California's baseline is that RVs are not intended as permanent dwellings and, unless a local ordinance allows otherwise, may generally be occupied only in mobilehome parks or special occupancy parks⁷.

One city rule is confirmed: camping in a residential yard needs the owner's or occupant's written permission, must be in the rear yard or a fenced side yard, requires sanitary toilet facilities within 100 feet, and may not exceed 3 consecutive days⁶. RVs on sites in flood Zones AH and AE must be on site fewer than 180 consecutive days, be fully licensed and highway-ready, or meet permit and anchoring requirements¹⁷.

A tiny home can be occupied in California only if it is approved as a recognized type such as a manufactured home, a code-compliant home, an RV or a park trailer, in a location approved for that type¹⁸. Mobile homes fit in the city's MH district, which is intended for mobile home parks¹⁹.

Building a home in Simi Valley: the steps, in order

1. Confirm the zoning district and lot standards with the Planning Division at (805) 583-6769⁹.
2. Check whether the parcel sits in a flood zone on the city's Flood Insurance Rate Map, since development in Zones AH and AE has added requirements¹⁷.
3. Hire an architect or engineer registered in California for the plans².
4. Submit plans to the Building and Safety Division and obtain construction permits before starting work².
5. Ask the city building department how septic or sewer service works for the lot³.
6. If you plan a second unit, note that California requires a permitting agency to approve an accessory dwelling unit application ministerially and to tell the applicant within 15 business days whether the application is complete²⁰.

What stays with Ventura County, and what to check before you buy

Land outside Simi Valley city limits follows Ventura County's rules, not the city's. For unincorporated land, see the Ventura County page, where the county requires building permits through its own Building and Safety Division¹³.

County-level numbers describe Ventura County, not Simi Valley alone. The county's effective property tax rate is 0.7%, with a median annual bill of $5,326²¹²². Typical home insurance runs about $1,643 a year²³.

Before you buy, confirm the parcel is inside city limits, its zoning district, flood zone, and who permits septic or sewer. The city offices above and the county Environmental Health Division can each answer part of that.

Watch-outs

• Searching "Simi Valley building permit" can lead to Ventura County's permit portal, but the county's building rules apply only to unincorporated land¹³.
• Septic permits inside Simi Valley do not come from Ventura County Environmental Health; the county refers city-limit questions to the city building department³.
• We could not confirm the city's rules for living in an RV or tiny home on a private lot, its building code edition, or its permit fees; ask the Planning Division or Building and Safety⁹².

Sources

1. Simi Valley Municipal Code 9-24.020 Purposes of Residential and Open Space Zoning Districts (Simi Valley), quoted and re-checked
2. City of Simi Valley, Building and Safety Division (Department of Environmental Services) (simivalley.org)
3. Ventura County Resource Management Agency, Environmental Health Division (rma.venturacounty.gov)
4. Simi Valley Municipal Code 9-24.020 Purposes of Residential and Open Space Zoning Districts (Simi Valley), quoted and re-checked
5. Simi Valley Municipal Code 9-24.020 Purposes of Residential and Open Space Zoning Districts (Simi Valley), quoted and re-checked
6. Simi Valley Municipal Code 6-5.01 Transient campsites (Simi Valley), quoted and re-checked
7. hcd.ca.gov (California statewide rule), quoted and re-checked
8. California Business and Professions Code Section 7044 (California statewide rule), quoted and re-checked
9. City of Simi Valley, Planning Division (Department of Environmental Services) (simivalley.org)
10. Simi Valley Municipal Code 9-24.020 Purposes of Residential and Open Space Zoning Districts (Simi Valley), quoted and re-checked
11. Simi Valley Municipal Code 9-24.050 Residential and Open Space District Setback Exceptions (Table 2-3) (Simi Valley), quoted and re-checked
12. Simi Valley Municipal Code 9-24.050 Residential and Open Space District Setback Exceptions (Table 2-3) (Simi Valley), quoted and re-checked
13. Building Permit Information - Ventura County Resource Management Agency, quoted and re-checked
14. Septic Systems / Wastewater Disposal, quoted and re-checked
15. Water Quality Control Policy for Siting, Design, Operation and Maintenance of Onsite Wastewater Treatment Systems (OWTS Policy) (California statewide rule), quoted and re-checked
16. 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
17. Simi Valley Municipal Code 7-5.607 Standards for recreational vehicles (Simi Valley), quoted and re-checked
18. Information Bulletin 2016-01: Tiny Homes (California statewide rule), quoted and re-checked
19. Simi Valley Municipal Code 9-24.020 Purposes of Residential and Open Space Zoning Districts (Simi Valley), quoted and re-checked
20. Accessory Dwelling Unit Handbook March 2026 (California statewide rule), quoted and re-checked
21. Effective property tax rate: Bolthole Index county data
22. Median property tax bill: Bolthole Index county data
23. Typical home insurance premium: Bolthole Index county data

Written October 16, 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.