Planning & Building

Under California law, an ADU can’t be required to have fire sprinklers if they aren’t required for the main house.

Prefab ADUs are usually faster and more price-predictable on flat lots with easy access. Site-built ADUs win on sloped or

Yes, you can build an ADU on a sloped lot, but expect a hillside premium of roughly $25,000 to $80,000

If you own a single-family home in California, your lot can very likely have at least one ADU. State law

Most ADUs take about 5 to 14 months from first planning to move-in, depending on the type. Plan on 1

You can usually build an ADU on a septic system, but septic capacity, not zoning, is often the real limit.

A prefab ADU typically takes about 4 to 7 months from signed contract to move-in, plus permitting time that should