Should I legalize my in-law unit in SF?

[Mike Lin]

I'm doing some renovations in my single-family house and have the opportunity to convert to two units if I want to. My architect warned me that it's difficult to undo this decision. Because they city wants more housing units, they rarely allow you to go back to a single-family home after converting to a two-unit. She also said that single-family homes have better resale value then comparable duplexes.

I plan to live here for at least another 10 years, but maybe forever. The second unit will either be a rental or home for a parent. I don't think I'll ever need the extra space. If anything, I'll need less space when my kids leave the house.

Is it true that I'll lose value by converting to a duplex? Does it make sense for me to keep it as a single-family home?