Vision ADU San Diego - Building Your Vision
Vision ADUSan Diego

Garage Conversion vs. New Construction ADU

Which ADU type is right for your property? Compare costs, timelines, ROI, and more.

One of the most common questions we hear from homeowners is: 'Should I convert my garage or build a new ADU from scratch?' Both are excellent options, but they differ significantly in cost, timeline, size potential, and ROI. Here's a comprehensive comparison to help you decide.

Feature
Garage Conversion
New Construction
Typical Cost
varies
varies
Timeline
4–6 months
6–12 months
Max Size
400–600 sq ft (limited by garage)
Up to 1,200 sq ft
Design Flexibility
Limited by existing structure
Full creative freedom
Foundation Work
Minimal (existing slab)
New foundation required
Permits
Generally easier approval
Full plan check required
Parking Impact
Lose garage parking (CA law exempts this)
No parking impact
Rental Income
varies
varies
Property Value Increase
varies
varies
ROI (Return on Investment)
Higher % return on lower cost
Higher absolute return
AB 1033 Condo Value
varies
varies
Energy Efficiency
Good (existing structure insulated)
Excellent (built to latest codes)
Backyard Impact
None (uses existing structure)
Reduces backyard space
Ceiling Height
Standard 8 ft
9 ft+ or vaulted

Garage Conversion

Pros

Lower cost
Faster completion (4–6 months)
Simpler permit process
No backyard space lost
Higher percentage ROI on investment

Cons

Limited by existing garage size
Lower ceiling heights
May feel less like a standalone home
Less design flexibility
Lower rental income potential

Best For

Budget-conscious homeowners who want quick rental income and have an existing garage they don't need for parking.

New Construction ADU

Pros

Up to 1,200 sq ft of living space
Full design flexibility
Higher rental income
Greater property value increase
Higher AB 1033 sale price

Cons

Higher cost
Longer timeline (6–12 months)
More complex permitting
Reduces backyard space
Requires new foundation

Best For

Homeowners who want maximum living space, the highest rental income, and long-term property value growth.

Our Verdict

Both options are excellent investments. If budget and speed are your priorities, a garage conversion delivers fast ROI with lower upfront costs. If you want maximum space, rental income, and long-term value, new construction is the way to go. Many of our clients actually do both — converting their garage first to generate immediate income, then building a detached ADU later. Whichever you choose, Vision ADU handles everything from design through construction.

Frequently Asked Questions

Not Sure Which Option Is Right for You?

Book a free consultation and our experts will assess your property and recommend the best approach.