CLEVELAND, Ohio - After years of behind-the-scenes planning, Playhouse Square Foundation is getting ready to stage its biggest real estate act: Building a 34-story apartment tower at the edge of downtown Cleveland's theater district.

The nonprofit organization will own the project, a $135 million investment comprised of a 319-unit rental building and an adjacent, 550-space parking garage at East 17th Street and Euclid Avenue. Hines, a global real estate firm, will serve as the development manager, shepherding the project without holding a stake in it.

Playhouse Square's decision to push forward on a long-held development dream comes during a rental renaissance for Cleveland, which is seeing proposals for new construction pick up as the supply of potential conversion projects - older buildings primed for residential makeovers - thins.

An apartment tower called One University Circle is being built on the city's east side, and a high-rise called the Beacon is earmarked to rise above a parking garage at 515 Euclid Ave. A handful of developers are trying to stretch Cleveland's skyline, while others are tying up neighborhood sites for smaller rental deals.

Yet economists across the country are asking how long the rental boom will last. Some markets are showing signs of slowing. And lenders are tempering their approach to apartments, making financing tougher to find.

Playhouse Square executives aren't worried. They aim to start construction on their tower by the end of the year and open the building by early 2020.

"We have vetted this pretty well," said Art Falco, chief executive officer for the performing arts district, which owns more than 1 million square feet of real estate and manages a comparable amount of space for other property owners.

"We have a database of about 800,000 people that come to Playhouse Square," Falco said. "So we have great comfort that a small percentage of those will want to live here."

Plans for the building show a slim, glassy tower at the southwest corner of East 17th and Euclid, with a parking garage just to the west, next to the Hanna Building.

The site, slightly over an acre, is a parking lot. Playhouse Square has owned most of the property since 1999 and acquired the last piece in 2015.

The nonprofit is putting that land into the apartment deal as equity, along with a little more than $10 million -- a gift from the Richard J. Fasenmyer Foundation to Playhouse Square's ongoing $100 million capital campaign. The district also received $1 million from the last state capital budget to help with construction of a garage.

The garage, with two floors underground and four levels above, will replace 140 surface parking spaces. An amenity deck, with a pool, heated gathering areas and a dog run for the apartment residents, will span the garage roof.

At 378 feet tall, including mechanical floors, the apartment building will be comparable in height to the Hilton Cleveland Downtown. The average apartment will be 880 square feet, though the units will range from one to three bedrooms.

Falco won't discuss potential rents, though they're likely to be among the loftiest in the market. Early this year, the average monthly rent in the downtown area was $1,400, according to Reis, Inc., a research firm that tracks market-rate, multifamily properties of at least 40 units. Vacancy was a mere 3.1 percent.

Due to modest job growth and a fairly stagnant number of people living in the region, rents in Cleveland aren't high enough to make new construction an easy sell. That's why Playhouse Square is shouldering its tower project in-house, rather than selling it to a developer.

Two local developers - the NRP Group, first, and then Hemingway Development - seriously considered the deal but ultimately passed when they couldn't make the numbers work.

Hines, which entered the talks late last year, reached a similar conclusion: The project wouldn't generate enough cash to satisfy an owner-developer. But it still could make sense for Playhouse Square, which views the buildings as a working endowment and will accept more moderate returns.

"For a developer who has a certain cost of capital, it just wasn't penciling out," said Brad Soderwall, a managing director at Hines. "But we felt strongly that the product itself would be very well received in Cleveland and could compete well and capture the highest possible rents that could be achieved in Cleveland."

Playhouse Square derives a third of its revenues from real estate and the rest from theater operations.

"We have the benefit of having a long-term perspective, a very different perspective than most investors," said Allen Wiant of Playhouse Square Real Estate Services. "We also have a perspective of having a broader portfolio where we can evaluate this return as raising the bar on the rest of our portfolio."

The nonprofit's holdings, other than the theaters, generate property taxes.

But the foundation does plan to seek property-tax breaks on the apartment tower and garage. Other major downtown developments have tapped a city residential tax- abatement program and have used tax-increment financing, which shifts part of the new tax revenues created by development to paying off project debt.

HollyAnn Eageny, a Chicago-area consultant who worked on a market study for Playhouse Square, acknowledged that it's getting harder to finance and build apartments in some cities. And she noted that there are thousands of new units on the drawing board in Cleveland - though not all of them will get built, and the ones that do won't all open at once.

Her firm, Tracy Cross & Associates, Inc., estimates that this metropolitan area can accommodate at least 500 new apartments each year for the next five years, without pushing the overall vacancy rate above 5 percent.

And, she added, there's a diverse group of renters, ranging from Millennials to slightly older professionals to downsizing suburbanites, who want to live in a new, efficiently designed building with lots of amenities and easy access to dining and entertainment on foot, by bicycle or via public transportation.

Those are the people that Playhouse Square plans to court.

"Everything in apartments is cyclical," Eageny said, "and there will come a period of accelerated construction followed by a lull. That's just the way it has always been. You have not overbuilt and, in fact, you're kind of catching up because there's been so little construction for so many years."