Step 1
Demo & rough grading
Week 1
Remove garage doors, old slabs, and utilities; call in rough grading or trench inspections as needed.
Cost Planning
Garage Conversion Cost Breakdown
See how structural upgrades, utilities, and finishes add up when transforming a Los Angeles garage into a code-compliant ADU.
Major cost buckets
Budget ranges we see on most conversions
| Category | Typical spend | Scope |
|---|---|---|
| Structural + slab upgrades | $25,000 – $55,000 | New footings, vapor barriers, and structural steel to make the slab habitable. |
| Building envelope | $32,000 – $58,000 | Framing, insulation, windows, exterior siding, roofing, and seismic bracing. |
| Mechanical, electrical, plumbing | $38,000 – $72,000 | New sewer laterals, water service, 200A panels or subpanels, HVAC, ventilation. |
| Interior finishes | $28,000 – $60,000 | Drywall, flooring, cabinetry, tile, fixtures, appliances, lighting. |
| Soft costs | $18,000 – $32,000 | Design, engineering, permits, impact fees, utility coordination, project management. |
Sample budgets
Two common conversion sizes compared side-by-side
| Scenario | Turn-key cost | Structure & envelope | MEP systems | Interior finishes | Soft costs | Notes |
|---|---|---|---|---|---|---|
| 400 sq. ft. studio | $165,000 | $62,000 | $28,000 | $45,000 | $20,000 | Ideal for in-laws or office |
| 600 sq. ft. 1-bed | $215,000 | $78,000 | $34,000 | $60,000 | $28,000 | Adds washer/dryer + storage |
Timeline
Inspection roadmap
Know when LADBS shows up so you can keep trades scheduled and materials staged.
Step 2
Underground utilities
Weeks 2-3
Inspectors verify sewer laterals, gas lines, and electrical conduits before backfill.
Step 3
Framing & shear
Weeks 4-5
LADBS reviews framing, anchorage, and fire separation between ADU and remaining garage walls.
Step 4
Rough MEP
Weeks 5-7
Electrical, plumbing, and mechanical rough inspections clear the way for insulation and drywall.
Step 5
Insulation & drywall
Weeks 7-8
Once insulation passes, crews hang drywall, tape, float, then prep for finishes.
Step 6
Final inspection
Weeks 10-12
Punch list complete, smoke/CO detectors tested, and final sign-off recorded for certificate of occupancy.
Cost savers
- ✔ Plan for ridge vents, daylight tubes, or sliders to reduce HVAC loads and avoid change orders later.
- ✔ Upgrade sewer and electrical during the conversion while trenches are open to save future mobilizations.
- ✔ Select durable but repeatable finishes—LVP flooring and quartz counters balance cost with rental longevity.
- ✔ Bundle landscaping or driveway replacements into the same permit to keep fees and inspections consolidated.
Quality must-haves
- ✔ 2x6 walls with dense-pack insulation to meet Title 24 without oversized HVAC.
- ✔ Fire-rated assemblies separating the ADU from shared walls or storage bays.
- ✔ Sound attenuation blankets between living space and any retained garage area.
- ✔ Future-proof conduit runs for solar, EV, or battery upgrades.
Want a line-item conversion estimate?
We review photos, measure the garage, and deliver a cost plan you can hand to lenders or builders.
Resource Library
More ADU planning guides
Use these deep dives to explore financing, scope, and cost decisions before we submit your plans.
Resource
Los Angeles ADU Permitting Checklist
Every milestone, document, and owner action needed to secure LADBS approval for a Los Angeles accessory dwelling unit.
Read guideResource
ADU Financing & Budget Guide
Compare HELOC, renovation, and construction loans while modeling soft costs, contingency, and rent-back payoffs.
Read guide