(Scott Sommerdorf | Tribune file photo) The Salt Lake City Council on Tuesay enacted changes to allow new accessory dwellings to be built more widely in residential areas across the city. John Armstrong, who hopes to build one on his mother’s property, posed in December next to her home near the site of the proposed dwelling. Based on a study of similar zoning changes in Portland and Denver, city planners estimate the new approach to ADUs could lead to between four and 25 new dwellings being built annually in Salt Lake City.