The Boulder City Council on Thursday, May 4, unanimously approved new rules that will make it easier for homeowners to build accessory dwelling units, or ADUs, which are smaller living spaces in backyards, basements or garages. The changes are part of an effort to increase housing density in neighborhoods zoned for single-family homes and chip away at the city’s longstanding housing shortage and affordability crisis.

The changes include eliminating “saturation limits” on the number of ADUs that can be permitted in neighborhoods. Such limits are uncommon in other cities, according to city officials, and the complicated permitting step has discouraged people from even considering building ADUs.

Councilmembers also increased the allowable size of ADUs. Detached ADUs can now be 800 square feet, up from 550 square feet. If property owners agree to cap rent and make the ADU “affordable,” they can build larger — up to 1,000 square feet for a detached ADU and 1,200 square feet for an attached ADU, such as those built in a basement or garage.

The new ordinance also seeks to simplify the permitting process. This includes treating ADUs more like any other home building permit and, in certain circumstances, giving more flexibility for meeting design standards and height limits.

The changes will take effect on Sept. 1, 2023. Depending on the outcome of a statewide land-use bill, additional restrictions, such as off-street parking requirements, may be nixed.

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  1. Is there any change for size limits if the primary residence is in the flood plain?

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