Following the International Code Council's (ICC) recognition of the ADU/Tiny House is the California Building Code. In an article on LinkedIn, Modular Lifestyles Inc. Vice President Steve Lefler takes a look at the three forms of ADUs.
Lefler states that while local government building codes do not have to accept this new type of housing or adopt an ordinance, they cannot preclude ADUs. He goes on to explain the regulations associated with ADUs:
AN ADU is an accessory unit for the purposes of calculating allowable density under the general plan and zoning. Local governments can dictate minimum and maximum ADU footprint sizes while maintaining local development standards. All impact fees, including water, sewer, park and traffic fees must be charged in accordance with fee mitigation act.