Can you build an ADU in Tarzana?

Can I build an ADU on my Tarzana lot?

In most cases you can. The city approves ADUs ministerially in every zone that allows houses, as long as there is an existing or proposed home on the lot ⁵. That covers Tarzana's RA, R1 and RE zones, which together hold nearly all of its single-family parcels ².

On a single-family lot, state law requires the city to allow three units together ⁸⁹:

• One detached backyard house of up to 800 sq ft, with 4-foot side and rear setbacks and a height of 16, 18 or 20 feet ⁷.
• One ADU made from existing space, such as a garage, a pool house or part of the house ⁸.
• One JADU of no more than 500 sq ft inside the house ⁹.

The city also has its own, larger option, the Ordinance ADU, which can reach 1,200 sq ft and two stories ⁶. In Tarzana, whether you can use it depends almost entirely on whether your lot is on the hillside. For the differences between these types, see our guides on JADU versus ADU, setbacks and height limits.

How big are Tarzana lots, and does lot size matter for an ADU?

Tarzana lots are big by Valley standards. We measured all 5,449 City of Los Angeles single-family parcels in 91356 on the LA County Assessor's parcel map: the median lot is 17,484 sq ft, half of all lots fall between 9,241 and 20,125 sq ft, and about one in four is 20,000 sq ft or more ¹.

The reason is zoning. About 64% of Tarzana's single-family parcels are zoned RA, the Suburban zone ², where every lot must have a minimum area of 17,500 sq ft ¹². That minimum lot area per house does not block a backyard house. State law bars minimum lot sizes for ADUs, and an ADU that meets state law does not count against the lot's allowed density ¹⁰¹¹.

A big lot brings its own questions. A backyard house far up a long driveway may need a Fire Department access review, which our 150-foot rule guide explains. The houses are newer than in much of the Valley, too: the median Tarzana house was built in 1963, and 40% were built before 1960 ¹.

How much of Tarzana is in the fire zone and the Hillside Area?

More than half. We tested every single-family parcel in 91356 against the city's map layers: 3,284 of 5,449 (60%) sit in the Very High Fire Hazard Severity Zone, and 2,960 (54%) sit in a Hillside Area ². Every one of those hillside parcels is also in the fire zone. Only 324 parcels (6%) are in the fire zone without being in a Hillside Area ².

The Fire Department lists Tarzana among the communities partly covered by the zone, which takes in most of the city's hilly and mountainous areas ¹³. In practice, the fire-zone parcels are almost all RA and RE11 lots, while only 79 of the 1,373 R1 lots are in the zone ².

Treat our fire-zone count as a floor. The city map layer we used was last edited in 2019. CAL FIRE issued new recommended fire hazard maps for Los Angeles on March 24, 2025, the city may not lower the hazard level the state recommends, and state law requires the city to adopt the maps by ordinance ¹⁴. Your own parcel's status is on ZIMAS ¹⁸.

My lot is in the fire zone and a Hillside Area. What can I still build?

You can still build the state-law units: the 800 sq ft backyard house, a conversion of existing space, and a JADU. City code bans ADUs on lots in both a Very High Fire Hazard Severity Zone and a Hillside Area, but City Planning says that ban may not be enforced on State ADUs ⁴.

What you lose is mostly the Ordinance ADU, the city's larger 1,200 sq ft, two-story option ⁴⁶. On a 20,000 sq ft hillside lot, that is the real trade-off: the land might hold more, but the guaranteed path tops out at 800 sq ft for a new detached unit ⁷.

The fire zone also changes how the unit is built and kept. The Fire Department requires owners in the zone to keep brush, grass and other hazardous vegetation cleared within 200 feet of any structure all year, and that includes the new one ¹⁵. Height on a slope is measured under the zone and Hillside Area rules like any other building ¹⁷. We cover the rest in separate guides:

• Building in a fire zone, including fire-resistant materials
• The Hillside Area rules, including street width and grading
• Fire sprinklers
• Soils reports and protected trees

Does the Mulholland Scenic Parkway plan affect my Tarzana ADU?

Only for the southernmost lots, and the rules for ADUs there are worth asking about early. By our count, 342 Tarzana single-family parcels (about 6%) sit inside the Mulholland Scenic Parkway Specific Plan area: 311 in its Outer Corridor and 31 in its Inner Corridor ².

City Planning's handout for the plan says projects that add more than 900 sq ft go to its Design Review Board for a recommendation, and projects that add less may be approved through an administrative clearance ¹⁶. The handout does not say how a state-law ADU is treated. If ZIMAS shows the Mulholland plan on your parcel, ask City Planning which review your ADU needs before you pay for plans ¹⁸.

Are other Tarzana homeowners actually getting ADU permits?

Yes, though fewer than in the flat Valley and mostly off the hillside. LADBS issued 48 ADU and JADU building permits in 91356 in 2023, 44 in 2024 and 74 in 2025 ³. Through October 3, 2026 it had issued 48, a pace about 15% behind 2025 ³. Of the 122 permits since January 2025, 61 were alterations to an existing building such as a garage, 40 were new buildings and 21 were additions; only 4 were JADUs ³.

Where those permits land tells the Tarzana story. Of the 214 ADU permits issued since January 2023, 59 (28%) were at addresses in the fire zone and 31 (14%) in a Hillside Area, even though 60% and 54% of homes sit in those zones ². Counted per single-family home, owners in the fire zone are pulling ADU permits at roughly a quarter of the rate of owners outside it.

These are permits, not homes; one project can carry more than one. For how Tarzana compares with its neighbors, see our ZIP-by-ZIP permit count, and our guides to Encino and the Woodland Hills fire zone.

What should I look up first for my Tarzana address?

Start with the free map lookups, then the questions that cost money to answer.

1. ZIMAS: your zone (RA, RE or R1), whether the parcel shows a Very High Fire Hazard Severity Zone, a Hillside Area or the Mulholland Scenic Parkway Specific Plan, and the permit history of the house and garage ¹⁸.
2. Which ADU path is open: if your lot is in both the fire zone and a Hillside Area, plan around the state-law units; if not, the larger Ordinance ADU may be possible ⁴⁶.
3. Distance from the street: on a deep lot, how far the backyard house would sit from the street, which decides the Fire Department access review.
4. Slope and soil: whether the building spot needs grading or a soils report, which our Hillside Area guide walks through.
5. Brush: how much clearing a new structure adds to your yearly brush work ¹⁵.

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), City of Los Angeles single-family parcels in ZIP 91356, LA County Assessor (Greenlight analysis). Facts checked 2026-10-12
2. Greenlight parcel count: Tarzana (91356) single-family parcels tested against City of LA GeoHub Very High Fire Hazard Severity Zones, Hillside Ordinance, zoning and Specific Plan layers, City of Los Angeles GeoHub (Greenlight analysis). Facts checked 2026-10-12
3. Building Permits Issued from 2020 to Present (N), dataset pi9x-tg5x, ZIP 91356, LADBS via City of Los Angeles Open Data (Greenlight query). Facts checked 2026-10-12
4. ZA Memorandum No. 143, Revision 1 (Aug. 2025), Q.42, Los Angeles City Planning, Office of Zoning Administration. Facts checked 2026-10-12
5. ZA Memorandum No. 143, Revision 1 (Aug. 2025), Summary of ADU and JADU Development Standards, Los Angeles City Planning, Office of Zoning Administration. Facts checked 2026-10-12
6. ZA Memorandum 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. Accessory Dwelling Unit Handbook (March 2026), Single-Family Detached ADUs, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
8. Accessory Dwelling Unit Handbook (March 2026), Allowable 66323 ADU Combinations, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
9. Accessory Dwelling Unit Handbook (March 2026), What is a JADU?, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
10. Accessory Dwelling Unit Handbook (March 2026), Density, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
11. Accessory Dwelling Unit Handbook (March 2026), Lot size, California Department of Housing and Community Development (HCD). Facts checked 2026-10-12
12. LAMC Sec. 12.07 RA Suburban Zone, Area, Los Angeles Municipal Code, reproduced by GoCodebook. Facts checked 2026-10-12
13. Fire Zone History: Very High Fire Hazard Severity Zone, Los Angeles Fire Department (LAFD). Facts checked 2026-10-12
14. 2025 CAL FIRE Fire Hazard Severity Zones Map Recommendation (Apr. 4, 2025), Los Angeles Fire Department (LAFD). Facts checked 2026-10-12
15. Brush Clearance Requirements, Los Angeles Fire Department (LAFD). Facts checked 2026-10-12
16. Mulholland Scenic Parkway Specific Plan: General Information, Thresholds of Review (CP13-3618, Jan. 20, 2026), Los Angeles City Planning. Facts checked 2026-10-12
17. ZA Memorandum No. 143, Revision 1 (Aug. 2025), Q.5 height, Los Angeles City Planning, Office of Zoning Administration. Facts checked 2026-10-12
18. Zoning Search (ZIMAS), Los Angeles City Planning. Facts checked 2026-10-12
19. Accessory Dwelling Unit Handbook (March 2026), Summary of Recent Changes, California Department of Housing and Community Development (HCD). 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.