Garage to ADU: Convert or Replace?
Short answer: California law allows ADUs in attached or detached garages, and cities cannot make you replace the parking you lose. Whether to convert the existing structure or replace it with a new backyard home depends on its foundation, framing, ceiling height, and location on the lot.
What state law says about garages
- ADUs may be located within attached or detached garages (Gov. Code 66314).
- When a garage, carport, or parking space is converted or demolished to create an ADU, the city cannot require those parking spaces to be replaced (Gov. Code 66314(d)(11)).
- If a detached garage is being replaced by an ADU, the demolition permit must be reviewed with the ADU application and issued at the same time (Gov. Code 66314(e)), and you generally cannot be required to post a placard or give written notice for the demolition unless the property is in a historic district (66314(f)).
- A junior ADU of up to 500 square feet can also be created in an attached garage, with no parking required (Gov. Code 66334).
- The city must approve or deny a complete application within 60 days when there is an existing home on the lot (Gov. Code 66317).
Sources: Government Code section 66314 (https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=66314); HCD Accessory Dwelling Unit Handbook (https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/adu-handbook-update.pdf).
Convert or start fresh?
Many older Bay Area garages were never built to house people. Before committing to a conversion, have the structure evaluated for:
- Foundation and slab condition, and whether it can support insulation, a raised floor, and new plumbing.
- Framing, ceiling height, and room for windows that meet egress and energy code.
- Where it sits: garages on a property line can keep their location when converted, while a new building must meet the setbacks your city allows for ADUs.
If the shell needs major work anyway, replacing it can produce a better home for a similar effort. That is what happened at Ramona in Albany: an old garage was replaced with a 475-square-foot, L-shaped studio with a kitchen, bathroom, built-in storage, and a wood deck, laid out so it can become a one-bedroom later.
Have a garage you're not using?
Send us a few photos and your address. We'll talk through whether converting or replacing makes more sense for your lot.
Garage ADU FAQs
What homeowners ask most.
Do I need to replace the parking I lose?
No. State law bars cities from requiring replacement parking when a garage or parking space is converted or demolished for an ADU.
What permits are involved?
Type Five secures everything: planning approval, the building permit, any demolition permit, fire-department sign-off, and utility coordination.
How long does it take?
For a new backyard ADU, most Type Five projects take about 10 to 12 months from first design meeting to move-in: roughly one month of design, two to four months of permitting, and about six months of construction.
Is Type Five a prefab company?
No. We're a design-build firm that constructs every ADU on site, which lets us fit tight lots and older garage footprints.