Garage conversions are one of the most cost-effective ways to add an ADU to your property. If you have an attached or detached garage that's mostly used for storage, you may be sitting on a significant untapped asset.

Is Your Garage a Good Candidate for Conversion?

Not every garage is ideal for conversion. Here's what we look at during a free assessment:

  • Size — 400 sq ft minimum is workable; 500+ sq ft is ideal for a comfortable 1-bedroom
  • Ceiling height — 8 feet minimum; 9–10 feet is much better
  • Foundation condition — slab-on-grade is typical and usually fine
  • Proximity to utilities — closer = lower cost
  • Detached vs. attached — both work, but detached offers more privacy

California JADU Rules

Junior ADUs (JADUs) can be created from space within an existing home, including garages that are attached. JADUs are limited to 500 sq ft and must share a common wall. They're subject to owner-occupancy requirements in most cities.

What's Involved in a Garage Conversion?

Structural Work

We evaluate and reinforce the existing structure as needed. Garage doors are removed and replaced with wall framing, windows, and an entry door. The slab is typically preserved as the finished floor after prep work.

Insulation

Garage walls are rarely insulated — we install proper wall and ceiling insulation to bring the space to residential standards. This is critical for comfort and code compliance.

Plumbing

Adding a bathroom and kitchen requires running new supply and drain lines. If the garage is near the main house plumbing, this is straightforward. If it's farther away, costs increase.

Electrical

We upgrade the electrical service to the garage and install proper residential wiring — outlets, lighting, HVAC, and a subpanel if needed.

Finishing

Drywall, flooring, kitchen, bathroom, paint, and trim. We use the same quality finishes we'd use in any ADU — because tenants expect it.

Cost Breakdown

Garage conversions in Santa Cruz County typically run $80,000–$150,000 all-in, including permits. Here's a rough breakdown for a 500 sq ft conversion:

  • Demo and structural: $8,000–$15,000
  • Permits and design: $12,000–$20,000
  • Plumbing: $10,000–$20,000
  • Electrical: $8,000–$15,000
  • Insulation and drywall: $6,000–$10,000
  • Kitchen and bath: $15,000–$30,000
  • Finishes and fixtures: $10,000–$20,000

The ROI Case for Garage Conversions

A $100,000 garage conversion renting for $2,000/month has a gross payback period of just over 4 years. After that, it's pure income. It's one of the highest-ROI home improvements available to California homeowners.

"I converted my detached garage into a studio for my in-laws five years ago. They moved out after two years and we've been renting it for $1,800/month ever since. Best investment I ever made." — Peninsula Construction client, Santa Cruz

Wondering if your garage qualifies? Schedule a free assessment and we'll take a look.