Garage conversion or detached ADU?

[Rhyna Orillaneda]

Hi. I'm from San Jose, Ca. I'm in the designing phase of my ADU but can't make up my mind wether I'll do a garage conversion or detached ADU. Lots of pros and cons for both but need your opinion.

After this ADU project, planning to buy my first rental property as well.

Appreciate all your feedbacks. Thanks so much.

[Caitlin Bigelow]

@Rhyna, I think budget will dictate for most homeowners what their ADU options are. I've helped nearly 200 California homeowners interested in ADUs and I'd say the #1 misconception is cost.

A garage conversion (usually) is the quickest and most cost effective way to get a 2nd rentable unit on the property. But it's not as simple as just throwing up some drywall and flooring. An architect (or draftsperson) will have to not only show the elevations and layout of the unit, but they will also have to submit a Title 24 (energy efficiency calculation) as well as the site plan for the entire property. Another thing to watch out for in garage conversions is water damage. Typically, garages aren't build with the expectation that someone will one day live there so they aren't as air tight as your home would be. Making sure any kind of leaks and water proofing happens before finishes is critical! 

I would expect to pay between 100-115K for a garage conversion. 

A stand-alone unit will definitely add value to your property, more so than a garage conversion. If you have the space and the budget it's a great option. There are a lot of fantastic options for building a stand-alone unit in the Bay! (I'm also in San Jose)

You can do:

• Stick build - fully customized takes the longest
• Panelized prefab - where the framing, electric, and plumbing all happen in a warehouse and walls are laid flat and then transported. This is advantageous for lots where access is limited. 
• Modular - a semi truck shows up at your home with more or less a finished unit. 

For a stand-alone unit (even prefab) I'd expect the costs to start at ~$400/450 per sq ft. Keep in mind costs with these are not linear and your first 400 square feet are the most expensive!

These all have pros and cons and there's a lot to consider. I'd be happy to connect you to some of my resources here! Feel free to reach out. I love helping homeowners with ADUs.