Homebuyers typically fall into one of two camps. Some are searching for move-in-ready conditions, while others seek a fixer-upper they can mold to suit their own needs and tastes. A Bethesda couple, hunting for new digs for themselves and their then-seven-year-old twin daughters, belonged to the latter group.

They saw possibilities in a 1936 red-brick, side-hall Colonial nestled within the leafy enclave of Greenwich Forest, a mile away from where they were living. Short on space and devoid of present-day amenities, the outmoded dwelling was ripe for a redo. And, happily, its quarter-acre-plus lot offered room to grow. “From the beginning, we knew we’d completely gut the house and change the footprint,” shares the husband, an attorney.

“Buying this house was an opportunity to start fresh and create something just for our family,” adds the wife, a nonprofit director. They quickly assembled a team—which included architect Luke Olson, designer Anne Pulliam and Structure builders—to orchestrate a large-scale renovation and expansion.

Thanks to local historic-district regulations, the front façade remained substantially intact; the preservation board approved a sensitive refresh and three new dormer windows. Olson also got the green light for a two-story, nearly 4,000-square-foot addition with a screened-porch extension and a detached, one-car garage.

Inside, the overarching aims were to establish extra breathing room and to forge a more family-friendly environment. “The existing house wasn’t functional for modern living,” relays Olson. “We completely reworked its floor plan, top to bottom, provided a rear and right-side addition, and expanded the basement. The challenge was creating a cohesive plan that tied the new and old together.”

On the first floor, the living room remained to the right of the foyer, but everything else was fair game. Walls shifted and the stairs were relocated to improve flow and carve out space for a powder room. To the left of the entryway, the existing attached garage was converted to an office. The addition allowed the dining room to expand and introduced an enlarged kitchen/breakfast area, a family room, butler’s pantry and mudroom. The architect explains, “The plan ties into how people use their spaces and live now, versus the formality of the previous design.”

As the envelope took shape, Anne Pulliam and her clients fleshed out a vision for the interiors. “They wanted a transitional style, but something a little different,” recounts the designer. “That meant injecting unexpected colors and patterns, as well as some architectural moments.”

Pulliam brought in frequent collaborator Alexander Smith of Mortar & Thatch to conjure architectural details that would capture the spirit of the old yet veer slightly more modern. Case in point: the streamlined staircase that now connects all four levels. Other millwork and new flooring they selected in tandem provide a clean base for the next layers.

With healthy doses of blue and green, the color palette borrows from the scenery outside—and a particular Liberty floral-print fabric. “We love nature and Anne was sensitive to that,” reveals the husband. “She was really good about bringing in the outdoors, both in the colors and the overall aesthetic.” The wife concurs, adding, “We wanted the interior to feel peaceful and calm, but we also wanted it to be fun.”

The inspiration textile (which now encases four pillows adorning the family room’s green sofas) combined the couple’s favorite hues and served as a springboard. “We designed the whole house off that one fabric and wove a cohesive feel throughout,” discloses Pulliam. A deep-blue tone pulled from the flowery print cloaks the living room; a lively green shade repeats in the dining room’s drapery panels. Mulberry and mustard accents are a common thread.

Pulliam employed wallpaper to multiply organic interest and bring an element of the unexpected. Her woodsy choice for the foyer sets the tone, while the powder room’s surprising selection, which depicts dinosaurs roaming through a verdant habitat, ignites conversation. Clouds, marigolds and stars can be spotted on other wall coverings throughout the home.

Kitchen designer Amy Collins developed cabinetry plans for the kitchen, butler’s pantry and mudroom, while Pulliam added panache to each space. A blue-and-white, hand-painted backsplash tile stands out against the white-painted cabinets in the kitchen and spattered wallpaper jazzes up the butler’s pantry.

Pulliam started virtually from scratch as she layered in furnishings, blending comfortable upholstered pieces with vintage finds and playful lighting. “We talked about the functional and aesthetic goals for each space and got to be creative,” she offers. “Nothing is too precious in this home, and every room can be enjoyed.” Performance fabrics, forgiving leathers, wipeable vinyl and natural-fiber rugs all make appearances in the livable tableaux.

One of the couple’s must-haves was a spacious primary suite, which the upper level of the addition allowed. To create a “happy and cheery” oasis, Pulliam washed the walls and vaulted ceiling in white paint and added touches of color for continuity. The reconfigured and expanded second floor harbors three additional ensuite bedrooms.

During the overhaul, the existing attic became a magical hideout for the now-tweeners. The basement excavation made way for a rec room (with a kitchenette), wine closet, gym and guest quarters.

Is the now-five-bedroom, 6,600-square-foot abode—with its airy, well-appointed spaces—the family’s forever home? Both owners respond affirmatively. The husband enthuses, “We’re so happy with how everything turned out.”