The 2-Unit Condo Conversion Question Everyone's Asking Me

I've recently started taking on condo conversion projects for 2-unit buildings, drawing on my architecture practice for the inspection prep, code corrections, and any legalization or ADU permit work that needs to run alongside the conversion. Lately, one question keeps coming up: what happens if my "2-unit" building actually has a third, unpermitted unit?

The short answer: you can still do the bypass conversion. But it’s worth understanding the full project needs before you start.

A quick refresher on the bypass

Since the SF condo conversion lottery was suspended in 2013, the 2-unit bypass has been the most reliable path to convert tenancy-in-common ownership into actual condos. The qualifications are narrow but workable: both owners must each hold at least 25% of the property (the threshold exists to keep people from gaming the system with micro-stakes), and both must have lived in the building as their primary residence for at least one year. The process itself takes about a year to complete - slower than anyone would like, but administrative and predictable, which counts for a lot in San Francisco permitting.

What inspectors are looking for

A building inspection is required as part of the process, and any code violations have to be corrected before the conversion completes. The big ones we see most often: unpermitted work, fire hazards, missing GFCI outlets, and fire-rated separations between units and the garage.

The good news (and this is the detail that saves owners real money) is that non-conforming conditions don't need to be brought up to current code, provided they were installed with permits at the time they were constructed. So if your stairs are too steep or your hallways too narrow by today's standards, but they were built that way legally? You're fine. Don't let a contractor talk you into ripping them out.

The UDU question, and the answer

So, back to the question. With all the recent scrutiny around unauthorized dwelling units, owners with a third unit on a "2-unit" building are increasingly nervous about whether they can still convert.

You can, but the outcome isn't three condos. It's two condos and a legal third unit that ends up on one of the two condos’ titles. The third unit becomes legal (a real win) and can be rented separately, but it can't be sold separately. Critically, your 3R report still needs to show 2 units for the building to qualify for the bypass in the first place. Check this before you do anything else.

Sequence matters

Here's the practical advice that's hardest to figure out on your own: if you have a UDU, submit the legalization or ADU permit before you submit the condo conversion application. Permits take at least six months to approve and another four to six for construction. Run them on parallel tracks, and the conversion finishes roughly on schedule. Run them sequentially, and you've added a year to your timeline.

Who to call

For the legal side, which is genuinely specialized work, we recommend Andy Sirkin's office, or his colleague Rosemarie MacGuinness. For the architecture, permits, code corrections, and project coordination side, that's where both Syncopated Architecture and Property Atlas come in. If you're thinking about converting and want to talk through the path, please reach out!

Brought to you by Property Atlas.