The former Leland Hotel in downtown Detroit is expected to undergo a $120 million-plus renovation that will convert the building into a mix of 339 affordable and market-rate apartments and add a 650-space parking deck.

Some details of the planned project, long discussed privately, are spelled out in a request for proposals obtained by Crain's on Wednesday afternoon.

The Leland, which now has about 300 apartments and extended-stay hotel rooms at 400 Bagley Ave. at Cass Avenue, is 22 stories with 372,000 square feet, about 91,300 of which are commercial, according to the RFP. It was built in 1927 and is on the National Register of Historic Places, according to Historic Detroit, which chronicles Detroit building history and architecture.

Construction is expected to begin in September and wrap up by March 2020, the RFP says.

Shane Napper, president of construction for Grand Rapids-based Rockford Construction, the development manager on the project, said there are about 150 residential tenants in the building, which was designed by C. W. and George L. Rapp.

Financing is planned from federal Low Income Housing Tax Credits; New Market Tax Credits; federal historic tax credits and other sources, Napper said.

The RFP also says that commercial and retail tenants — City Club and a diner — will remain in the building during construction. Currently vacant residential units will be renovated, existing tenants will be moved into those renovated units, and then their vacated units will be renovated.

"We will not be moving out any existing tenants. We will be keeping this building in a great occupied shape," Napper said.

Approximately 20 percent of the 339 units are expected to be for affordable housing, with some of those devoted to residents making 50 percent or less of the area median income.

Responses to the RFP are due by Feb. 2 to Rockford Construction. The GC contract is expected to be awarded between Feb. 28 and March 9, according to the RFP.

If completed, the redevelopment would be one of several large-scale projects planned for the area.

The Ilitch family has fielded responses to an RFP for the Fine Arts Building facade on Adams Street and plans another six residential developments and redevelopments with nearly 700 units, and construction on a new 288-unit building has begun on the site of the former Statler Hotel at Washington Boulevard and Park Avenue.

Michael Higgins has owned the Leland Hotel building for years through the Leland House Limited Partnership Co., which was registered in 1980.

Detroit-based Kraemer Design Group is the project architect and engineer, according to the RFP.