Writer Tracy Mitchell Griggs is based in Annapolis, Maryland.

Fond memories of summers spent on the Delaware coast and the pending birth of her son inspired a Washington, DC-area financial services executive to return to Rehoboth Beach. “It was my goal to recreate for my son the great childhood experiences I had here,” she recalls. Her real estate search ultimately resulted in the purchase of a 1960s-era oceanfront home in North Shores, a community adjacent to Cape Henlopen State Park. The executive and her family enjoyed the modest, two-story ranch house for more than six years before deciding to renovate it. “I ended up hiring architect John Lester and builder Ron Coffin, who had years of experience building waterfront properties in Delaware,” she says.

 Today, little of the original ranch home remains visible. The addition of two more floors and structural upgrades to protect against flooding and hurricanes led Coffin to encase the original house in a framework of steel I-beams and girders. “Using wood pilings is a more typical approach in this type of renovation, but it made sense in this design to utilize steel in order to support the two-story addition,” he says. “The underlying frame is something that more closely resembles commercial construction. The third and fourth floors are structurally independent of the first two floors and, in the event of flooding or a storm surge, there is a greater likelihood for the house to maintain its structural integrity.”

 Over this framework, Lester, whose practice is based in nearby Lewes, Delaware, designed the building exteriors to combine the shingled façades of Nantucket beach homes and the columned porches of Southern plantations. He chose composite materials for window trim and other architectural elements to reduce the need for constant repainting and maintenance. Porches and decks extend from both the front and back to meet the owner’s request for ocean views and outdoor spaces for relaxing and casual entertaining with close friends and family. They add nearly 6,000 square feet to the already generous, 7,500-square-foot home.

Inside, the owner tapped designer Shanon Munn of Springfield, Virginia-based Ambi Design Studio to conceive a sophisticated yet livable décor based on her previous experience with Munn on a house in Chevy Chase, Maryland. The living and entertaining spaces on the first and second floors are designed with kids in mind while the bedrooms and sitting areas on the third and fourth floors offer a more refined retreat for the owner and her guests. “This was my first opportunity to design interiors for a waterfront house,” says

 Munn, who incorporated nautical elements without sacrificing luxury. Steel cables used in sailboat construction, for example, form the balusters in the staircases. Other seaside touches include shell-filled lamps and sailboat-themed textiles.Munn, who promotes “green” design practices, furnished the rooms with antiques, showroom samples and new pieces upholstered in natural fabrics such as silks and linens. On the first and second floors, the wool carpeting and cotton upholstery are not only earth-friendly, but stand up to kids and sand. The four-poster bed in the master bedroom is made from sustainable rattan and is dressed in bedding by Coyuchi, a manufacturer that uses  organically grown cotton. Benjamin Moore paints with low volatile organic compounds (VOCs) are applied on the walls throughout. When deciding on a color scheme, Munn returned to her client’s preferred palette. “She likes gold, red and blue tones, so I didn’t stray too much from those when selecting colors for most of the house.”

On the main level, the kitchen, dining space and adjacent family room are arranged in an open floor plan that is oriented to a large deck on the ocean side. Warm, gold-painted walls provide a backdrop for a trio of blue-striped upholstered sofas that surround the room’s fireplace and harmonize with a large maple dining table that seats 10. Striped area rugs in both family and dining rooms cover the recycled heart pine floors with patterned practicality that adds visual punch. “We kept the accessories and art to a minimum in these rooms,” says Munn. “In a space this large, the tendency would be to fill it up, but we wanted the focus to be on the incredible ocean views and dunes.”

 The more formal living room on the third floor features a custom-designed sofa and two pairs of butter yellow leather recliners centered on a vintage walnut coffee table. “The color palette for the room started with the floral Scalamandré fabric on the sofa,” says Munn, adding that the room’s blue-and-cream-patterned carpet is a showroom sample. “It was a bit of luck and ended up being the perfect size and color for this room.” Built-in cherry cabinetry on the north wall of the room opposite the sofa houses a fireplace, shelving for books, accessories and a large, flat-screen television.

The designer had just three and a half months to create the overall plan for the interior finishes and lighting, and to install the furnishings. “Our first meeting to discuss the house was in late January and she was eager to have everything completed in time for summer,” recalls Munn. To avoid the wait required when ordering furniture through manufacturers, Munn designed the living room sofa and chairs and had them built by area craftsmen. “The chair design was one I had created for the National Symphony Orchestra Decorators’ Showhouse—my client liked it so much I reproduced it for her,” says Munn.

 On the top floors, the colors are calmer and details more elegant in accordance with the owner’s requirements. “The master bedroom is designed to feel like a luxury hotel suite in contrast to the brighter, more casual rooms on the lower level,” says Munn. The designer disguised structural supports in the room as pilasters that frame a niche around the bed. The space between them is painted a slightly darker shade than the walls to emphasize it as a focal point within the room. A silk-skirted table and a mirrored chest flank the bed and a window seat on the opposite side of the room provides a touch of romance. “This is one of my favorite rooms in the house,” says the owner. “Shanon designed a space that makes me feel like I am staying at the Ritz-Carlton.”