Bountiful council signals support for 25-foot ADU roof height, prefers 8-foot setbacks and 20-foot sidewall cap

Bountiful City Council members signaled support during a work session for measuring detached accessory dwelling unit (ADU) height to a 25-foot peak while adding an 8-foot side and rear setback and a 20-foot sidewall limit, though no formal vote was taken.

Planning Director Francisco Astorga opened the discussion by reviewing the city zoning-code definition for how building height is measured and showing staff and council proposal diagrams that compared the current code, a council-requested 25-foot peak approach, and the staff recommendation. "We did feel comfortable with the staff's original recommendation," Astorga said, referencing staff's preferred approach of a 25-foot overall maximum paired with a 20-foot sidewall cap.

The discussion focused on how different roof forms — gable/hip, gambrel, mansard, and flat roofs — affect usable second-story space under differing measurement rules. Astorga and staff used 24-foot-wide garage-based examples (a common envelope for a two-car garage plus living area) and explained that roof pitch and measuring convention determine whether an ADU can practicably accommodate a second story. Don Simons, the city's building code expert, summarized the office practice for dormers: "If more than 50% of the roof form is created by the dormer, then we count that as the roof."

Why it matters: ADU measurement rules change how much livable space a property owner can create on top of a garage or in a detached structure, and they affect neighboring…