Ask three builders what an ADU costs and you'll get three numbers, because the honest answer depends on the lot. What we can give you up front: the ranges L.A. homeowners are actually paying in 2026, what an all-in number includes, and the specific things that move a project up or down inside those ranges.
2026 market ranges by ADU type
| ADU type | Typical all-in range | Note |
|---|---|---|
| Garage conversion ADU | $120K – $220K | $250 – $450 / sq ft |
| Junior ADU (JADU, up to 500 sq ft) | Usually the least expensive path | Converts existing interior space |
| Attached ADU | Between conversion and detached | Shares structure with the house |
| Detached new-build ADU (500–800 sq ft) | $240K – $400K+ | $300 – $550 / sq ft |
Hillside lots, historic districts, and difficult access push the top of every range higher. A well-built garage on a flat lot with good sewer access sits at the bottom of its range; an older garage that needs structural work can approach detached new-build money, which is exactly the kind of thing a site visit settles before you commit to a direction.
What an all-in number includes
The construction contract is the biggest line, but it isn't the whole number. A real ADU budget carries five parts:
- 01
Design & engineering
Architectural plans, structural engineering where required, and Title 24 energy calcs. Most clients bring finished plans; if you don't have an architect, we refer you to ones we've built with.
- 02
Permits & city fees
Plan check, building permit, and school or utility fees. These vary by jurisdiction: Pasadena, the City of Los Angeles, and L.A. County each run their own counter and their own fee schedule.
- 03
Sitework & utilities
Sewer connection or lateral upgrades, electrical panel capacity, trenching, grading, and foundations. This is the part of the budget the lot itself decides, and the reason two identical floor plans can price very differently.
- 04
Construction
Foundation, framing, roofing, mechanical, electrical, plumbing, insulation, drywall, and finishes. The largest slice of the budget, and the one that scales most directly with square footage.
- 05
Finishes & fixtures
Cabinetry, counters, flooring, tile, appliances, and lighting. The same unit can land in a different cost tier on selections alone.
Five ways to keep the number down
- Reuse an existing structure. A garage conversion skips the foundation, framing, and roof that make up a large share of a detached build.
- Keep the volume simple. A rectangular single-story unit with a simple roofline builds faster and cheaper than complex massing, without reading as cheap.
- Right-size it. Cost scales with footprint. A well-planned 500 sq ft unit often rents for nearly what an 800 sq ft one does in the same neighborhood.
- Pick stock finishes where they don't show. Spend on the kitchen face and the bathroom tile; save on what a tenant never notices.
- Settle the plan before permits. Changes on paper cost hours. Changes mid-construction cost change orders. We lock scope and selections before submittal so the plan you approve is the plan that gets built.
Paying for it
Most L.A. ADU projects are funded with home equity (a HELOC, a home-equity loan, or a cash-out refinance) or a renovation loan that lends against the property's value after the ADU is built. California's $40,000 CalHFA ADU grant is currently paused and not accepting applications. The details on both are in our ADU financing guide and CalHFA grant status guide.
Get the number for your lot
The free on-site consultation is where ranges become your number: we walk the property, check sewer, panel, and structures, and give you a scope you can hold us to. PMK Development, licensed California general contractor, CSLB #1008209, building across Los Angeles and Pasadena since 2015.
ADU cost questions, answered
How much does an ADU cost in Los Angeles in 2026?
In the current L.A. market, garage conversions typically run $120K to $220K all-in, and detached new-build ADUs around $240K to $400K or more. Those are market ranges, not a quote. The lot, the structure type, and the finish level decide where a specific project lands.
What's the cheapest way to add an ADU?
Converting an existing garage or interior space is almost always the least expensive path, because the foundation, walls, and roof already exist. A Junior ADU (JADU) that converts a bedroom or bonus room within the house is usually cheaper still.
Is a per-square-foot price a reliable way to budget?
Only as a rough check. Per-square-foot figures spread fixed costs (permits, utility connections, sitework) across the footprint, so a small ADU can show a high per-square-foot number while costing less overall. Budget from an all-in scope, not a multiplier.
Does an ADU add value to my property?
ADUs generally add appraised value and rental income potential in Los Angeles, and some lenders will count the finished unit's value when financing the build. How much depends on your neighborhood and the unit itself; a local appraiser or agent can give you a read for your street.
How do I get a real number for my property?
A free on-site consultation. We walk the lot, check sewer, panel, slope, and structures, and give you a scope and a number you can hold us to. Phone estimates for ADUs are guesses; site conditions move the price too much.
Market ranges checked August 2026. Every project is priced from its own drawings and site conditions.