If the LDS Church's real-estate planners get their way, a few people in Salt Lake City will be living 400 feet above ground.

Plans for City Creek Center, a mixed-use development proposed by The Church of Jesus Christ of Latter-day Saints to replace the downtown Crossroads Plaza and ZCMI Center malls, call for at least five residential towers.

One of those buildings would be 415 feet tall — or 32 stories. That's only 20 feet shorter than the city's tallest structure, the LDS Church Office Building.

The tallest residential tower — at this point, developers are calling it only Tower 2 — would be built on 100 South between Main Street and West Temple, next to the Marriott Hotel. It would not be part of City Creek Center when the complex is set to open in 2011 but would be a second-phase addition to be built later, based on demand for more housing in the center.

City Creek Center spokesman Dale Bills said developers want the tall building because of "an interplay of engineering and economics."

The church wants a building taller than 100 feet to allow for more housing units. The added height requires more structural-stability elements, and once those elements are added, a lot of new height potential opens up.

"You get to a certain height and say, 'I might as well go a little taller,'" said Mark Gibbons, president of the church's real-estate arm, Property Reserve Inc.

But PRI will need the Salt Lake City Planning Commission's approval to build the high-rise, as well as three other housing towers on the mall blocks. City ordinance requires conditional-use approval for midblock buildings — meaning those more than 165 feet from a corner — that are planned to exceed 100 feet in height.

Two towers on South Temple would book-end historic Richards Street on the Crossroads block and would be 125 feet tall. Another South Temple Tower, on historic Regent Street west of the Zions Bank building, would be 185 feet high.

The four 100-foot-plus towers would have a combined total of 319 condominium units. If all the buildings were restricted to 100 feet, that total would drop to 96 units.

The center will include a number of other housing units, including a tower at the corner of West Temple and South Temple where the Inn at Temple Square used to stand and rental units above retail components throughout the project. None of those residential elements will require height exemptions. In total, the two blocks would have between 420 and 430 residential units.

Those units will include apartments for rent and condos for purchase. Gibbons said no announcements have been made yet on prices, but there will be a "wide range."