What an ADU costs in Pacoima: garage conversion vs. new backyard house

How much does an ADU cost in Pacoima, all in?

It depends mostly on whether you convert a garage or build new, and the published prices put those two paths about $95,000 to $135,000 apart. CALI ADU, a Los Angeles design-build firm, lists a straight conversion of a two-car garage into a studio or one-bedroom at $140,000 to $200,000 and up, and a conversion with an addition of up to 500 sq ft at $175,000 to $245,000 and up ³. For new construction, the independent contractor estimates on the same firm's plan page run from $180,000 to $200,000 for a 400 sq ft studio to $275,000 to $295,000 for an 800 sq ft two-bedroom ⁴.

Those are one company's numbers, and lower totals exist. Block Renovation profiled six Los Angeles-area garage conversions with published totals from $75,000 to $300,000; the $75,000 job turned a detached garage into a one-bedroom unit with a kitchen and bathroom ⁵. Treat any single range as a starting point, and ask every builder in writing what their number includes.

If you want the line-by-line budget for a detached unit, What an ADU really costs in Reseda walks through each line. This guide is about the choice most Pacoima owners face first.

What are other Pacoima homeowners actually building?

Mostly garage projects and fairly large new units. We pulled every ADU and JADU building permit LADBS issued in 91331 from January 6, 2025 through October 1, 2026, leaving out supplemental permits: 217 in all ¹.

• New buildings: 91 permits. The median lists 1,040 sq ft, and 33 are described as two-story ¹.
• Garage conversions with no added space: 38 permits. The median lists 346 sq ft ¹.
• Garage conversions with an addition: 51 permits. The median lists 705 sq ft ¹.

That makes 89 of 217 permits, about 41 percent, that started from a garage ¹. On the median 6,968 sq ft lot in 91331 ², there is often room for either path; Can my Pacoima lot fit an ADU? covers how to check yours.

Do not budget from the valuation printed on these permits. The median declared valuation is $32,500 for a straight garage conversion and $120,000 for a new unit ¹. That is a number written on the application, not a price, and it sits far below every builder range above.

Why do garage conversion prices vary so much?

Mostly because of the garage you start with. CALI ADU says the single biggest variable is the condition of the existing garage, and that panel capacity, sewer distance and any required seismic retrofit also move the number ³. LADBS's own rules for conversions show where that money goes.

• Foundation. Existing foundations may stay if they are in good condition and met conventional construction requirements when built ⁶. If they do not, the footings need new work.
• Ceiling height. A converted unit needs a minimum ceiling height of 7 feet throughout ⁷.
• Walls near the property line. In a conversion without sprinklers, exterior walls less than 5 feet from the property line must be 1-hour fire-rated, which can be done with 5/8-inch Type X gypsum board on the whole interior side of the wall ⁸.
• Fire sprinklers. They are required only if the main house already has them, or if major remodeling of the house triggers them ⁹.

Before any of that, find out whether the garage was ever permitted. How to check if your LA garage was permitted walks through the records search.

What does a new backyard house cost, and does the size change the fees?

Size changes both the build price and the fees. On CALI ADU's plan page, the contractor estimates climb from $180,000 to $200,000 at 400 sq ft, to $275,000 to $295,000 at 800 sq ft, to $325,000 to $350,000 at 1,000 sq ft, with fixed plan fees of $7,490 to $12,990 ⁴. The firm also notes that fixed costs such as the foundation, sewer connection, electrical service, permit fees and HVAC are similar regardless of size ³, which is why small units cost more per square foot.

Two size lines in state law are worth knowing before you pick a plan.

• 750 sq ft. As of January 2026, no impact fee may be charged on an ADU of 750 sq ft of interior living space or less; above that, impact fees are charged in proportion to the size of the main house ¹⁰. The median new ADU permit in Pacoima lists 1,040 sq ft ¹, so most new units here are above this line.
• 500 sq ft. An ADU under 500 sq ft of interior living space is treated as not adding 500 sq ft of assessable space under the Education Code's school-fee rule ¹¹. The median straight garage conversion in Pacoima, at 346 sq ft ¹, is under both lines. ADU school fees in LAUSD covers the rest.

State law also lets a city cap a new detached ADU it must approve under that section at 800 sq ft of living space, with 4-foot side and rear setbacks ¹². Pre-approved plans can cut design time; see LA's standard ADU plans.

Which costs does a garage conversion avoid?

A conversion skips the water connection, the parking replacement and the setback question, but not the panel or the sewer.

• Water connection. For an ADU built inside existing space, such as a garage, the city or utility may not require a new or separate utility connection or charge a related connection fee, unless the ADU is built with a new house or sold separately ¹³. A new detached unit can be required to have one ¹⁴. If you need or choose one, LADWP's new 1-inch domestic service with a 1-inch meter is $7,407 for fiscal year 2026/2027 ¹⁵. More in Do I need a new water meter for an ADU?
• Parking. When a garage is converted to an ADU, the city may not require you to replace those parking spaces ¹⁶.
• Setbacks. No setback is required for an ADU built inside an existing accessory structure ¹⁷, so an old garage close to the line can stay where it is.
• Electrical panel. Both paths add load. One Los Angeles electrical contractor puts a DWP panel upgrade at $3,500 to $7,500 ¹⁸. See Do I need a 200 amp panel?
• Sewer. Both paths need a working line to the street. If the main is far away, read Sewer main over 200 feet from your lot.

What does an all-in budget look like on a typical Pacoima lot?

Adding up only the sourced lines, a straight garage conversion comes to about $143,000 to $213,500 and up, and an 800 sq ft backyard house to about $287,000 to $325,000 before impact and school fees.

Straight garage conversion, about 350 sq ft:

1. Conversion: $140,000 to $200,000 and up at one builder's published range ³; lower totals have been reported ⁵.
2. City plan check and permit fees: about $3,000 to $6,000 for a standard ADU in the City of Los Angeles, by that builder's estimate ³.
3. A panel upgrade, only if the load calculation calls for it: $3,500 to $7,500 ¹⁸.
4. No required water connection, no impact fee at 750 sq ft or less, and under the 500 sq ft school-fee line ¹³¹⁰¹¹.

New 800 sq ft backyard house:

1. Construction: $275,000 to $295,000 ⁴.
2. Plans: $8,990 for that fixed-fee plan ⁴.
3. City plan check and permit fees: about $3,000 to $6,000 ³.
4. A new water service, only if required or chosen: $7,407 ¹⁵.
5. A panel upgrade, only if needed: $3,500 to $7,500 ¹⁸.
6. Impact fees in proportion to the main house, because 800 sq ft is over the 750 sq ft line, and school fees ¹⁰¹¹.

The low ends assume your lot needs no panel or water work. Knowing which of these lines apply to your lot before you pay for plans is the kind of thing a lot check settles. For the costs outside construction, see ADU soft costs in Los Angeles.

Quick answers

Sources

1. ADU and JADU building permits issued in ZIP 91331, January 2025 to October 2026 (Greenlight analysis of LADBS permit data), LADBS via City of Los Angeles Open Data (data); Greenlight (method). Facts checked 2026-10-09
2. Lot sizes of single-family parcels in ZIP 91331 (Greenlight analysis of the County Assessor parcel layer), Los Angeles County Office of the Assessor (data); Greenlight (method). Facts checked 2026-10-09
3. How much does it cost to build an ADU in Los Angeles?, CALI ADU (Los Angeles design-build firm; builder-published prices). Facts checked 2026-10-09
4. Signature ADU plans: plan fees and estimated cost to build, CALI ADU (plan company; independent licensed GC estimates). Facts checked 2026-10-09
5. Garage conversion to ADU in Los Angeles: contractors and real projects, Block Renovation (contractor marketplace; published project totals). Facts checked 2026-10-09
6. Information Bulletin P/BC 2026-150, Accessory and Junior Accessory Dwelling Units: Foundation, Los Angeles Department of Building and Safety (LADBS). Facts checked 2026-10-09
7. Information Bulletin P/BC 2026-150: Interior Environment, Los Angeles Department of Building and Safety (LADBS). Facts checked 2026-10-09
8. Information Bulletin P/BC 2026-150: Fire-Resistance Rated Construction, Los Angeles Department of Building and Safety (LADBS). Facts checked 2026-10-09
9. Information Bulletin P/BC 2026-150: Fire Protection, Los Angeles Department of Building and Safety (LADBS). Facts checked 2026-10-09
10. Gov. Code §66311.5(c)(1), as amended and renumbered by SB 543 (Stats. 2025, ch. 520), California Legislature (chaptered bill text, posted by LA County Planning). Facts checked 2026-10-09
11. Gov. Code §66311.5(c)(3), as amended and renumbered by SB 543 (Stats. 2025, ch. 520), California Legislature (chaptered bill text, posted by LA County Planning). Facts checked 2026-10-09
12. Gov. Code §66323(a)(2), as amended by SB 543 (Stats. 2025, ch. 520), California Legislature (chaptered bill text, posted by LA County Planning). Facts checked 2026-10-09
13. Gov. Code §66311.5(d), as amended and renumbered by SB 543 (Stats. 2025, ch. 520), California Legislature (chaptered bill text, posted by LA County Planning). Facts checked 2026-10-09
14. Gov. Code §66311.5(e), as amended and renumbered by SB 543 (Stats. 2025, ch. 520), California Legislature (chaptered bill text, posted by LA County Planning). Facts checked 2026-10-09
15. Schedule of Charges for Water Facilities, Fiscal Year 2026/2027, Individual Installations (Domestic), Los Angeles Department of Water and Power (LADWP). Facts checked 2026-10-09
16. Accessory Dwelling Unit Handbook (March 2026), Parking, California Department of Housing and Community Development (HCD). Facts checked 2026-10-09
17. Accessory Dwelling Unit Handbook (March 2026), Setbacks, California Department of Housing and Community Development (HCD). Facts checked 2026-10-09
18. DWP electrical panel upgrade, LA Pro Electrical (one contractor's published range). Facts checked 2026-10-09

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.