Can you build an ADU in Canoga Park or West Hills?

Is my Canoga Park or West Hills lot big enough for a backyard house?

Almost always. We measured every City of Los Angeles single-family parcel in the three ZIPs on the LA County Assessor's parcel map ¹:

• 91303, Canoga Park (south of the rail line): 2,059 homes, median lot 7,490 sq ft, half of all lots between 6,742 and 7,643 sq ft.
• 91304, Canoga Park and northern West Hills: 7,823 homes, median lot 8,610 sq ft, half between 7,508 and 11,104 sq ft. About 40 percent of lots here are 10,000 sq ft or larger.
• 91307, West Hills: 6,740 homes, median lot 7,764 sq ft, half between 7,500 and 9,336 sq ft.

An 800 sq ft backyard house uses about a tenth of a typical lot in any of the three. Size alone rarely rules a lot out, and state law does not let a city set a minimum lot size for an ADU ¹⁹. Here the next two questions matter more than lot size.

Is my lot in a fire zone or a Hillside Area?

It depends sharply on the ZIP. We tested the center point of every single-family parcel against the city's Very High Fire Hazard Severity Zone and Hillside Area map layers ¹:

• 91303: none in the fire zone and none in a Hillside Area.
• 91304: 1,422 in the fire zone, 1,113 in a Hillside Area, and 262 in both.
• 91307: 1,913 in the fire zone, or 28 percent, and none in a Hillside Area.

So West Hills 91307 has the most fire-zone homes of the three, but the hillside label lands only in 91304, mostly along the northern and western edges. A Hillside Area is simply any area shown on the city's Hillside Area Map, so the answer is a line on a map, not how steep your yard looks ²¹.

Two cautions. The city fire layer we used was last edited in 2019, and on March 24, 2025 CAL FIRE issued new recommended fire hazard maps for Los Angeles, which the city must adopt by ordinance ¹¹. A lot near any line can land on either side, so look up your own parcel on ZIMAS, the City Planning map that shows a parcel's zoning, overlays and permit history ¹⁵.

What changes if my lot is in the fire zone, a Hillside Area, or both?

You can still build a state-law ADU on any of them. What changes is which city ADU you can choose and how you build.

• Fire zone only (most of the 3,335 fire-zone homes): the city's ban does not reach you, because it applies only to lots in both zones ⁷. Plan check will require the fire-resistant materials and methods of Chapter 7A ⁹. Our Woodland Hills fire zone guide and Granada Hills fire zone guide cover what that means.
• Hillside Area only (851 homes in 91304): either ADU type is open, but grading usually needs a soils or geology report before permits issue ²⁰. See our hillside guide.
• Both (262 homes in 91304): the city code prohibits ADUs on these lots except in a few listed cases, but City Planning says that restriction may not be enforced on state-law ADU types ⁷. In practice that means an 800 sq ft detached backyard house, a garage conversion or a junior ADU, not the city's larger Ordinance ADU.

Sprinklers are a separate question: an ADU cannot be required to have them if the main house was not, and the ADU cannot trigger them in the house ²³. See our sprinkler guide.

How big can my ADU be, and should I convert the garage or build new?

Los Angeles gives you two tracks. A State ADU can be a detached new unit of up to 800 sq ft with 4-foot side and rear setbacks ³, 16 feet tall, or 18 feet near transit, plus 2 feet if the roof pitch matches the house ⁶, and the city's floor-area limit cannot be enforced against it ⁵. An Ordinance ADU can reach 1,200 sq ft and two stories ⁶, but floor area, front yard and lot coverage limits can shrink it ⁵. On the bigger 91304 lots it is more often realistic; on a lot in both zones it is off the table. The city must also allow one ADU from existing space and one junior ADU alongside a new detached one ⁴.

The houses differ by ZIP. The median 91303 home was built in 1954 with 1,372 sq ft of living space, against 1963 and 1,876 sq ft in 91304 and 1960 and 1,618 sq ft in 91307 ¹. Older tract houses often have a detached garage. State law allows converting it to an ADU ¹⁶, requires no setback when the ADU stays inside the existing structure ¹⁸, and bars the city from making you replace the lost parking ¹⁷. Our Reseda garage conversion guide walks through that path.

Which community plan and specific plans cover my lot?

Most of the area falls under the Canoga Park-Winnetka-Woodland Hills-West Hills Community Plan, which the city says was last updated in 1999 and is being rewritten now ¹². The northern part of 91304 is in the Chatsworth-Porter Ranch Community Plan, last updated in 1993 ¹³; 93 of the 345 ADU permits issued in 91304 since 2020 were filed under that plan ².

The plan page for this area lists the Valley Circle/Plummer St Scenic Corridor and the Mulholland Scenic Parkway among its specific plans ¹². The Valley Circle plan dates from 1978, and its standards apply to any subdivision or parcel map within 1,500 feet of Valley Circle Boulevard between Roscoe and Plummer, or of Plummer Street east to Topanga Canyon ¹⁴. A backyard house that does not split the lot is not a subdivision, and City Planning says state-law ADUs are exempt from local zoning, design and development standards ⁸. If you live near Valley Circle, still check ZIMAS for any specific plan on your parcel ¹⁵.

Are Canoga Park and West Hills neighbors actually getting ADU permits?

Yes, and 91304 is having its busiest year in the data. LADBS issued 70 ADU and JADU building permits in 91304 from January 1 to October 3, 2026, more than in any full year since 2020; the highest was 61, in 2025 ². Over the same months of 2025 it issued 37, so this year is running close to double.

The other two ZIPs are steady, not rising. West Hills 91307 issued 46 permits in that period this year and 46 last year, and Canoga Park 91303 issued 28 against 31 ². Our permits by ZIP guide ranks them against the rest of the Valley.

Of the 306 ADU permits issued in the three ZIPs since January 2025, 169 were alterations to an existing building, 96 new buildings and 41 additions ². More than half of recent work happens inside something already there, such as a garage. These are permits, not homes: one project can carry more than one, and a permit issued is not a unit finished.

What should I check first, and in what order?

Start with the map, because here the map decides more than the yard does.

1. ZIMAS: your zone, the fire zone and Hillside Area rows, any specific plan, and the permit history of the house and garage ¹⁵.
2. ADU track: in both zones, plan on a State ADU; otherwise decide whether 800 sq ft is enough or you need the Ordinance ADU ⁶⁷.
3. Fire access: on a deep lot, fire lane access applies where any part of new construction valued at $50,000 or more is 150 feet from an improved street ¹⁰. See the 150-foot rule.
4. Slope: on a Hillside Area lot, whether grading needs a soils report ²⁰.
5. Utilities: sewer, water meter and panel, which our Winnetka guide lists in order.

This is the kind of thing a lot check settles in one pass, before you pay for plans.

Quick answers

Sources

1. LA County Assessor parcel layer (LACounty_Parcel), single-family parcels in ZIPs 91303, 91304 and 91307, City of Los Angeles; matched to City of LA GeoHub Hillside Area and Very High Fire Hazard Severity Zones layers, LA County Assessor / City of Los Angeles GeoHub (Greenlight analysis). Facts checked 2026-10-12
2. Building Permits Issued from 2020 to Present (N), dataset pi9x-tg5x, ZIPs 91303, 91304, 91307, LADBS via City of Los Angeles Open Data (Greenlight query). Facts checked 2026-10-12
3. Accessory Dwelling Unit Handbook (March 2026), 66323 Units: Single-Family Detached ADUs, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
4. Accessory Dwelling Unit Handbook (March 2026), 66323 Units: allowable combinations, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
5. ZA Memo No. 143 Revision 1, Accessory Dwelling Units (August 2025), Los Angeles City Planning, Office of Zoning Administration. Facts checked 2026-10-12
6. ZA Memo No. 143 Revision 1, ADU types summary table (Ordinance ADU vs State ADU), Los Angeles City Planning, Office of Zoning Administration. Facts checked 2026-10-12
7. ZA Memorandum No. 143, Revision 1 (LAMC Chapter 1): Implementation of the ADU Ordinance and State ADU Law, issued Aug. 1, 2025, Q.42, Los Angeles City Planning / LADBS. Facts checked 2026-10-12
8. ZA Memorandum No. 143, Revision 1 (LAMC Chapter 1): Implementation of the ADU Ordinance and State ADU Law, issued Aug. 1, 2025, section on GC § 66323(a), Los Angeles City Planning / LADBS. Facts checked 2026-10-12
9. Accessory Dwelling Unit Plan Check Correction Sheet (PC/STR/Corr.Lst.20A1, Rev. 8/03/2021), item C.1, Los Angeles Department of Building and Safety (LADBS). Facts checked 2026-10-12
10. Accessory Dwelling Unit Plan Check Correction Sheet, item B.7, Los Angeles Department of Building and Safety (LADBS). Facts checked 2026-10-12
11. 2025 CAL FIRE Fire Hazard Severity Zones Map Recommendation, Los Angeles Fire Department. Facts checked 2026-10-12
12. Canoga Park - Winnetka - Woodland Hills - West Hills Community Plan, Los Angeles City Planning. Facts checked 2026-10-12
13. Chatsworth - Porter Ranch Community Plan, Los Angeles City Planning. Facts checked 2026-10-12
14. Valley Circle Boulevard/Plummer Street Scenic Corridor Specific Plan, Ordinance No. 151,615, Los Angeles City Planning. Facts checked 2026-10-12
15. Zoning Search (ZIMAS), Los Angeles City Planning. Facts checked 2026-10-12
16. Accessory Dwelling Unit Handbook (March 2026), Detached ADUs, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
17. Accessory Dwelling Unit Handbook (March 2026), Parking, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
18. Accessory Dwelling Unit Handbook (March 2026), Setbacks, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
19. Accessory Dwelling Unit Handbook (March 2026), Lot size, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
20. Grading Inspections, Los Angeles Department of Building and Safety (LADBS). Facts checked 2026-10-12
21. Zoning Code glossary: Hillside Area, Los Angeles City Planning. Facts checked 2026-10-12
22. Accessory Dwelling Unit Handbook (March 2026), Summary of Recent Changes, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
23. ZA Memorandum No. 143, Revision 1 (LAMC Chapter 1): Implementation of the ADU Ordinance and State ADU Law, issued Aug. 1, 2025, Q.31 (Gov. Code § 66314(d)(12)), Los Angeles City Planning / LADBS. Facts checked 2026-10-12

Greenlight is not a contractor, architect or engineer, and this is not legal advice. Rules change; every fact here shows the date we last checked it.