SAN FRANCISCO (KCBS) -- The city-by-city patchwork of often-maddening rules that govern whether you can have a legal in-law apartment are about to change with a new statewide law that's designed to create more affordable rental housing.

Governor Jerry Brown signed SB-1069 into law in part of the state's response to the affordable housing crisis.

The law allows homeowners to remodel to accessory dwelling units, commonly known as in-law or granny units, without all the costs that many cities impose now.

Authored by State Sen. Bob Wieckowski (D-Fremont), the law speeds up the approval process for in-law unit construction, removes secondary utility hook up fees already paid for by the main unit owners, and eliminates parking requirements if the in-law unit is near public transit.

Leslie Smith works in San Francisco, but was priced out of the city's rising rents, so she decided to renovate a home in Oakland and add a second unit.

"I am ecstatic that it's all going through. Without the second unit, I wouldn't have been able to afford here," Smith told KCBS.

It's estimated that if just 10 percent of homeowners added a second unit of some type, it could add 150,000 units to the Bay Area.

"Now I get to be the homeowner, and have someone else pay my mortgage," Smith said.