The first three condominium purchases in the Liberty Building were made by a single first-time homeowner, an empty-nest couple and a retired couple, according to developer Jake Christensen. And interest shown by the single buyer’s friends helped lead to a significant change in the rehab plan.

“I expected mostly retirees,” said Christensen, vice president of Nelson Construction Services. However, “we’ve had a lot of interest from single young professionals. They don’t want the warehouse type of condo, but they’re looking for smaller units.” In response, some planned 2,000-square-foot units will be cut into smaller units of 900 to 1,200 square feet. Christensen said that option will probably be taken on floors four, five and six of the 12-story building at 418 Sixth Ave.

Demolition work continues throughout much of the building, which Nelson Construction bought for $1.1 million two years ago. Christensen has visited similar projects all over the country and said similar work is being done now in Kansas City. “In bigger cities like Minneapolis and Chicago, they did this years ago,” he said.

Nelson Construction, based in Urbandale, plans to spend $25 million on the Liberty rehab and a parking ramp now taking shape on the opposite side of Sixth Avenue. The six-level ramp will provide a designated parking space for each resident of the Liberty Building and the nearby Equitable Building, now being renovated into high-end condos by Bob Knapp.

Model units have been finished and furnished on the 10th floor, and Christensen said 20 or 30 groups of potential buyers take a look at them in a typical week. The first owners are expected to take possession of their condos in May; the schedule calls for four floors to be completed this summer.

One 1,800-square-foot condo unit is priced at $450,000. The 900- to 1,200-square-foot units will be priced at about $180,000. Units on the upper floors command higher prices than those below.

To the north and east, upper-floor residents will have wide views of downtown and the state Capitol. The southern and western windows face the Ruan Center and other tall office buildings.

Patios will be added to the exterior wall of a few units. Inside the building, all residents will get their own 120-square-foot storage unit separate from their condo.

A large truck-mounted crane parked on Grand Avenue is being used to disassemble a smokestack on the south side of the building and will also be used to remove exterior fire escape stairs that no longer meet code requirements. The crane will remain on the street for another couple of weeks.

A second-story roof, surrounded by the taller parts of the building and Two Ruan Center, is to be spruced up with landscaping elements, but is not intended for use by the residents.

On the skywalk level and on the first floor looking onto Grand Avenue, Metro Fitness & Tanning L.L.C. has a 10-year lease to operate an exercise and spa facility. That’s expected to open late this summer, and will be available for use by anyone, Liberty resident or not, who buys a membership.

Shiffler Associates Architects P.L.C. of Des Moines is handling the architectural aspect of the project, and Clive-based Worth.In.Ex Corp. has done much of the design work.