Scott Prendergast of Apex Custom Homes has built high-end houses for wealthy clients in Northern Virginia for 20 years. But this newly built house along the Potomac River in McLean was a departure from his usual projects.

When he was first approached about the property, Prendergast was sure it was a prank.

“A guy calls me out of the blue and says his mother was selling a lot on the river and was I interested,” he said. “I thought it was a joke at first.”

Distinguished homes for sale in the D.C. region

McLean modern house | The 2021 house, which was built by Apex Custom Homes, overlooks the Potomac River. It is listed at just under $11.5 million. (Cesar A Olivares/Townsend Visuals)

Prendergast made them an offer, which they accepted. Because he didn’t have a client and was building the house on “spec,” he had the freedom to choose whatever style he wanted. Prendergast and his wife, Shannon, had teamed up to design many houses together, and this one was no different. When considering what style of house to build, he knew he wanted it to stand out from other homes in the area

“I am so tired of the architecture in our area,” Prendergast said. “I wanted to do something extremely unique and something that you might even find in California or some other areas that are just a little bit more progressive. . . . We think we have a pretty good formula of putting out really stunning product that you just don’t see everywhere. That is what sort of drove me to do this house.”

What Prendergast had in mind was a house that leaned toward modern but didn’t have the coldness that some modern houses evoke. However, some of his design decisions came down less to his preference than what the zoning regulations allowed.

“In Fairfax [County], you have a 35-foot median height restriction,” Prendergast said. “Because this lot, on the north side, the river side, is so steep, when we designed the house with a pitched roof, we exceeded the median height by 17 feet.”

Which is why the house ended up with a nearly flat roof. It is slightly pitched but from the street appears flat.

The roof height was just one of the entanglements Prendergast had to sort out during the permitting process.

“It was a real challenge getting this permit” to build the house, he said. “It took me about 10 months just to get the permit, and I built the house in 11 months.”

Prendergast’s goal was to make this house stand out from the others in the area, and it does. The house is made of concrete blocks covered in stucco, and the bright white stucco really pops against the natural surroundings. A heated concrete driveway leads to a parking court and the entrance.

A pair of 10-foot iron doors open to a soaring entry hall with a 24-foot ceiling, Italian porcelain tiles on the floor and niches for artwork on either side. To the right of the stairs is the great room. Its wall of retractable glass doors opens to a terrace that overlooks the Potomac River. A two-sided fireplace and 10-inch plank brushed-oak flooring warms the room.

Next to the great room is the main floor owner’s suite with panoramic river views. The owner’s bathroom has heated floors, a soaking tub and a steam shower with five shower heads, music, light therapy and aromatherapy. The closets, which will be customized however the buyer desires, include a steam clothing-care system.

The dining room has wine storage behind a wall of glass. In the kitchen, richly veined Italian porcelain covers the walls and the island. The countertops are quartz.

Four bedrooms with en suite bathrooms are upstairs.

On the lower level, the large entertaining area has a wet bar with a backsplash of Italian porcelain tile that matches the fireplace surround. There’s also another bedroom, a media room and access to a lower terrace with an infinity-edge heated pool that overlooks the river and floats 20 feet up in the air.

No detail has been overlooked in the house.

“When you do a spec house, what we try to do is make it so that somebody’s not going to say, ‘I wish we had this,’ ” Prendergast said. “We’re using our experience about what our clients’ feedback over the years have given us. We’re looking at trends, mostly out west that are coming to the East Coast.”

Although Prendergast took some chances with this house, he has no regrets.

“It was really fun and challenging and very rewarding,” he said. “I wouldn’t change anything, to be honest about it. . . . I love it. I am so pleased with the way this house turned out.”

The six-bedroom, six-bathroom, 12,000-square-foot house is listed at just under $11.5 million.

Listing agents: Phyllis Patterson and Mark Lowham, TTR Sotheby’s International Realty.