The Salt Lake City Planning Commission on Wednesday unanimously signed off on four 100-foot-plus residential buildings planned for downtown, including one that would be among the state's tallest structures.

The towers are planned as part of The Church of Jesus Christ of Latter-day Saints' proposed City Creek Center development. They needed conditional-use approval from the commission because they exceed the 100-foot height standards set for downtown buildings that aren't located on corners.

One building — planned for 100 South between West Temple and Main Street — far exceeds 100 feet. It would reach 415 feet in the air, rivaling the 435-foot LDS Church Office Building and the Wells Fargo building, which stands 440 feet tall, if you count a radio tower on top. If you don't, it's only about 400 feet.

The 100-foot limit isn't a restriction so much as a trigger for architectural review to avoid a skyline dotted with "cereal boxes," planning staffer Doug Dansie said. A number of midblock downtown buildings are taller than 100 feet, but each is judged on an individual basis to make sure it doesn't block views or create an eyesore.

The 415-foot building, currently being called only Tower 2, would not be part of City Creek Center when the complex is set to open in 2011 but would be be built later, based on demand for more housing in the center.

Officials with the church's real-estate arm, Property Reserve Inc., have said they want the tall buildings because of engineering requirements and desire to bring more housing downtown.

Plans call for at least 420 condominium and apartment units to eventually populate the two blocks currently housing the Crossroads Plaza and ZCMI Center malls.

In addition to Tower 2, the commission Wednesday approved two towers on South Temple that would bookend 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, was approved to stand 185 feet high.

Those four 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.

"We believe that residential is the lifeblood of revitalizing downtown," PRI president Mark Gibbons said, a belief that has been backed up by designers' visits to downtowns nationwide.

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 more than 500 residential units.

Preliminary plans for Tower 2, drawn by architects Zimmer Gunsel Frasca, show a restaurant and retail space at the tower's ground floor. The lower levels would have more units, with levels 24 through 32 only six condos per floor, ranging from 935 to 2,015 square feet.