The challenge: Jen Kyllonen loved her longtime home, a century-old house in Minneapolis’ East Isles neighborhood. “It’s a feel-good house,” she said. But with 1 ½ baths upstairs, there was only one shower, which her family of four had to share. She wanted to convert some of their second-floor space into a master bedroom with its own bathroom.

The team: Designer Victoria Sass, Prospect Refuge Studio; builder Personal Pride Construction.

The back story: The house, built in 1906, had at one point been converted into a boardinghouse, and an addition was put on the rear, resulting in an awkward layout upstairs. “The space had been added to and chopped up, with oddly sized rooms and a lot of hallway,” said Sass. The hallway was narrow, and one of the bedrooms was “long and skinny — 8 by 24 feet,” said Kyllonen. “It was weird space” — although it did get great light.

New floor plan: Reworking the second floor and eliminating one of the four bedrooms freed up space to create a master bedroom with its own full bathroom. The hallway also was widened “so it’s not a tunnel,” said Kyllonen.

The vision: “I wanted it to be like a jewel box experience — my own little retreat,” said Kyllonen. To create that experience, Sass incorporated details inspired by historic references — without trying to re-create a period. “This wasn’t a historical renovation,” Sass said. “It’s a fresh take without going totally rogue.” She advises clients to “find pieces you love, and don’t stress too much about if they go together. Especially in these older homes that have been more worked on, it feels more natural to have miscellaneous styles and metals.” That suited Kyllonen. “Everything is not super matchy-matchy. It makes it feel more curated, more individual, versus looking like everyone else’s bath.”

Architectural details: The house has a Craftsman aesthetic, with wainscoting and detailed molding on the main level, while the upstairs was simpler and more spare. To echo the detailing on the main floor, Sass designed a board-and-batten wall treatment in the new bathroom. “It elevated the room to make it as nice as the rest of the house,” said Kyllonen.

Furniture-inspired: A custom walnut vanity, with a Carrara marble top and handmade wire pulls with an unlacquered brass finish, evokes a vintage chest of drawers. “It was modeled on a dresser,” said Sass. “It feels like a piece of furniture.” Originally Kyllonen wanted two sinks, but there wasn’t quite enough space. “It’s always a game of inches,” said Sass. Instead, there’s a trough sink with two faucets, which allowed for more counter space and more storage underneath than with a standard sink.

Textured flooring: The heated bathroom floor is covered in Arto tile. “It’s an outdoor paver product,” said Sass. Lightly sealed, it will patina over time. “It’s lovely underfoot, with a warm cobblestone feeling,” said Sass. At first Kyllonen had her doubts. “I was worried it would look like a ’70s bathroom,” she said. But Sass reassured her, and Kyllonen is glad she took the leap of faith. “Each tile is unique,” she said. “It looks like terra cotta and looks true to the house. And it feels divine. Like massaging your feet.”

Distinctive doors: A custom pocket door between the bedroom and bathroom mimics other doors in the house. And an arched custom oak door to the linen closet creates a beautiful focal point in the bathroom. “It literally made the room,” said Kyllonen. Vintage doorknobs from old doors were repurposed on the new doors.

Perfect color: “I love green,” said Kyllonen, especially the first shade that Sass suggested for painting the bathroom walls — Breakfast Room Green, a Farrow & Ball hue. “It’s a sage green with depth,” said Kyllonen. “I felt like it was historically correct for the house.”

Refreshed flooring: In the bedroom, the original wood floor was “roll-y” and uneven. The maple floorboards were removed, then reinstalled, augmented with wood from the upstairs demolition and finished with a clear stain.

Space and light: The new bedroom has a dormer and a radiator at one end; one of the challenges was “to create balance in an asymmetrical room,” said Sass. There was only one spot for the bed, which meant placing the headboard in front of some windows. A spindle headboard with a low profile was chosen. “The bed does overlap the windows, but you’re still getting light through the spindles,” said Sass. The bed is walnut to “reference the walnut in the bathroom,” said Sass, who also helped Kyllonen find bedding to complement the space. “A simple duvet. Not a lot of pillows. A tidy Shaker aesthetic.”

Statement curtains: The window treatments that frame the bed are made from fabric panels that Kyllonen picked up at a rummage sale. The patterned fabric, by designer John Robshaw, features a stylized daisy pattern. “Daisies were my mom’s favorite flower,” said Kyllonen of her late mother. “Every time I see daisies, I think of her. That’s what makes the room special — not having every piece new from the store.”

Space-saving accents: A pair of narrow leather nightstands flank the bed. Sass had ordered them for another client who changed her mind, so Kyllonen got them for half-price. “They don’t take up too much space,” she said. Each is topped with a slender Ralph Lauren table lamp in unlacquered brass.

Modern chandelier: The three-armed chandelier, in black matte metal, is a reproduction of a Serge Mouille design from the 1940s. “It’s more midcentury,” said Sass. “It adds to that collected aesthetic and makes it more interesting.” Also, its wide branching arms help illuminate the corners of the room.

Budget: The original budget for the 350-square-foot project was $75,000, Kyllonen said, but it went a bit over that because of some of her choices, including adding extra insulation to the attic.

The result: The owners’ suite became Kyllonen’s retreat. “It’s a great space — really pretty with the morning sun,” she said. “It feels like it’s always been there but way nicer than in the olden days. It’s perfect.”

So perfect that she didn’t get to enjoy it as long as she expected to. Kyllonen is a real estate agent with Edina Realty, and not long after she finished the project she started working with a client who was moving from Washington, D.C., and wanted a home in Kyllonen’s neighborhood. The client couldn’t find the right house — until Kyllonen invited her to a neighborhood gathering and gave her a tour. The client loved Kyllonen’s house — especially the owners’ suite. “She walked in and said, ‘This is amazing!’ ” Kyllonen said. From then on, the client wanted only Kyllonen’s house. She finally relented and sold her home.

“It happened so fast,” said Kyllonen. “I really, really miss it.” But she’s not sorry she undertook the project. “We improved it and handed it off better than we received it.”