A new state law bars local jurisdictions from restricting ADUs in residential areas.

According to Costa, “LD 1829 encourages new construction of accessory dwelling units, known as ‘ADUs,’ by pulling back zoning restrictions that differ widely from town to town and setting new statewide standards, including allowing three dwelling units on every lot.”

The law required cities to allow at least four units per lot in “designated growth areas” and reduces minimum lot sizes for ADUs. It also prohibits cities from imposing stricter height limits, setbacks, and other dimensional standards for ADUs than for single-family homes and does not require owners to occupy one of the units.