The Tudor Building is a mix of retail spaces and affordable apartments in downtown St. Louis. 

Most construction pros agree that building from scratch is usually easier than renovating an old building.

Bringing a structure built in a bygone era up to modern standards often entails a lot of challenges - walls that can't be moved, columns to work around and utilities with which to deal. And that could turn out to be the easy stuff.

The developers transforming the former Tudor Building at 1901 Washington Avenue in St. Louis ran up against an unusual challenge when they decided to turn the large, two-story building into apartments - how to get light to interior rooms that would have no windows.

To meet that challenge, crews installed tunnels that bring natural light to the otherwise dark rooms.

"It's a big metal tube that reflects light like a skylight," Tim Estepp, co-developer of the project, said. "But it's actually a tube that leads to a skylight."

Estepp, with partners Dan Holak, Pete Rothschild of ­Rothschild Development and Red Brick Management, and Robert Wood of Robert Wood Realty are turning the building into 21,000 square feet of commercial retail space and affordable housing, with 64 one- and two-bedroom apartments. They also are putting affordable housing in nearby 1818 Washington, with 39 apartments and 9,300 square feet of retail space; and in 1900 Washington with 34 apartments and 8,000 square feet of retail space.

"It's challenging to take these old buildings that are only two stories and put units in there," Estepp said. "You've got sound issues you've got to deal with. You've got space-planning issues. You need to get as many units as you can in there. You've basically got deep buildings and what you have to do is put some rooms in the middle of the building."

Estepp said tax credits tied to the affordable housing component and to the historic nature of the buildings made the projects doable.

Rothschild, who has had a lot of experience renovating old buildings, said that obstacles go with the territory. In this case, the buildings were not built originally with housing in mind.

"The standard boiler plate challenge of older buildings is that every one is different," he said. "Many times things need to be changed substantially from what they were created to be. This building had retail storefronts on the first floor. The back of the first floor was used for storage and deliveries. The second story was a warehouse, but over the years it had been used for different things. Actually, a haunted house was in the building for a few years."

Rothschild said the projects are part of an overall effort to create a neighborhood.

"It's different than downtown and because of that, it will appeal to different people," he said. "The scale of the building is a bit less intimidating. There's more space between buildings. Parking and traffic are less difficult."

Estepp called the response to the Tudor Building "tremendous."

"We haven't even opened the doors yet, and we've got darned near half the apartments already reserved," he said.

Because the apartments are designated as "affordable," tenants must make 50 to 60 percent of the area's median income. Rents are $795 for a two-bedroom apartment and in the low $600s for a one-bedroom unit.

Rothschild and his partners enjoy working with old buildings, even if it's not necessarily the most profitable development path.

"If you talk to any general contractor or developer involved in new construction, they will rightfully question the sanity of people that get involved in rehabbing old buildings but it's the ultimate green development because you're recycling an entire building," Rothschild said.

"If it was all about the money, we'd all be building warehouses in Fenton or something."