A two-story-high addition on the back of a Capitol Hill rowhouse created a bright, airy room. But its double French doors, which led to the backyard and parking, meant the space also functioned as a pathway.

"Our biggest challenge was how to place existing furniture in a way that best used the whole space," the homeowner said.

It didn't help that in the room's original layout, a daybed was pushed lengthwise against the right wall directly opposite the sofa, which was along the left one. Wasted space sat in between.

Lauren Liess Interiors: thepurestyle.com

"It felt like a junior high school dance, with the boys on one side and the girls on the other," the homeowner said.

Interior designer Lauren Liess was enlisted to improve the floor plan and make it multitask for work, rest and parties. She was also asked to introduce warmth to the midcentury furnishings.

"When I first saw the space," Liess said, "I thought it was such a pretty room. The light was amazing, and I could see that the homeowners had collected nice pieces. It had great potential."

Liess repainted the walls from cool sage to warm ivory. "The space still felt like an addition, so I painted the door frames black to create a sense of permanence," she said.

A large sea grass rug was custom-fit to the room, grounding the high vertical space and providing textured flooring. But the change with the most impact came with redesigning the floor plan.

"I began by floating the daybed away from the wall, so it could be accessed from both sides," Liess said.

The perpendicular angle of the daybed increased seating options, while delineating an office niche. The desk transforms into a bar for parties.

There are two other defined areas in the newly multifunctional space: a reading/conversation nook with armchairs and a reading lamp, and a main seating area with a sofa. Coffee tables can be easily removed for big gatherings.

To add warmth to the room, Liess worked with natural fabrics in neutral hues, with pops of color and pattern, as well as organic textures. She also created a more transitional feel with the new furnishings.

This transitional approach met the homeowners' broader design quandary -- the husband leaned more toward contemporary styles, and the wife preferred traditional. They already owned mostly modern furniture, so without being heavy-handed or going super-conventional, Liess integrated select clean-line furnishings.

"I put in traditional elements, like the skirted ottoman, curtain panels, wingback chairs and antique urn lamps," she said.

Visual variety and balance are also important in such a vertical room. Before, the furniture was on the same horizontal plane, but Liess mixed up heights, using higher- and lower-profile furnishings.

"You get used to a space," the homeowner said. "It was helpful to have a designer walk in with a fresh perspective."