On a late fall morning in 2012, McNair leads a tour of the restoration to date.

Once, carriages dropped off and picked up visitors under an arched stone porte cochère off what’s now Mohican Road, and that’s where visitors enter today. A shambles when the McNairs bought the place, the porte cochère is back to its original state, with tapered stone columns and rebuilt high steps leading into the house.

In the large foyer, 8-foot-tall, 4- and 5-foot-wide pocket doors open on either side into the living and dining rooms.

Doors, stairs, banisters, moldings and panels around the windows throughout are solid chestnut, the grain restored after being stripped of layers of old paint. Prized for its rich, beautiful grain and durability, chestnut hasn’t been used in construction since the early 1900s, when a blight decimated the tree in this country. But the wood at Baltzley has held up well over 120 years, and where it has needed replacement, oak has been stained to match the original chestnut.

French doors and floor-to-ceiling pocket windows in all the rooms provide access to a large, semicircular covered porch along the entire river side of the house. Pocket windows—common in the French Quarter of New Orleans, where McNair spent several years—also function as doors. The lower sash recesses into the floor, and the upper sash lifts up into the upper wall and ceiling. McNair finds a lot of French influence in the home—not surprising, given that Chandler, the architect, studied in Paris.

On the first two floors, McNair points out the plaster crown molding, meticulously matched to the original in every room, and the windows whose glass panes have been molded to fit 19th-century sashes. Those windows are less energy-efficient and five times more costly than the modern windows McNair installed in the new kitchen and porch, but that’s the price of authenticity.

To ensure that integrity for the entire house, McNair drew upon a number of sources. From the Theophilus P. Chandler Collection at the University of Pennsylvania, he obtained high-resolution photos of the castle and grounds taken in the 1890s. He used them as reference for decorative trim, moldings and fixtures. “We’d look at it carefully, figure out what was here, give it to the carpenters and say, ‘Here’s what I want.’ ”

He also consulted scrapbooks from Carol Schafer and Cook, who owns several original Baltzley eggbeaters and accounting books once belonging to the brothers.

McNair honors the home’s history in other ways, too. In the basement hallway, workers found a circular hole—part of a Civil War-era well, he believes—filled with hundreds of bottles and other artifacts. He plans to place tempered glass over the hole and has had niches built into the basement walls to display the found objects, including tools, nails, pieces of old bicycles and period photographs.

Meanwhile, the dirt floor of the basement was hand-dug down about 18 inches in order to install a stone floor, and gunk was meticulously hand-chipped from basement walls. There’s now an exercise room and bath under the new kitchen; a large cedar closet has been built under the porte cochère; and a 12-foot-by-7-foot wine cellar occupies previously unfinished basement space.

On the main floor, the rooms now look much as they did in 1890, except for the new kitchen, built where a side porch once stood. Period photos show a butter churn on that porch, which was just outside the original kitchen, but today there’s a Thermador professional-quality gas range and oven, two dishwashers, two refrigerators, a microwave, an undermount sink and granite countertops. Hanging in the center of the kitchen is the intricate gas and electric fixture that once lit the porte cochère. Gas fixtures were originally installed in Baltzley, but were electricity-ready in anticipation of the new power source.

The five second-floor bedrooms—where the Baltzleys and their guests once slept—have been transformed into his-and-her offices, with a third room holding office equipment, and two other rooms reserved for guests. Doors lead onto the roof of the glassed-in porch below. This spring, a travertine floor will be installed on the porch roof, along with outdoor furniture, so the couple can work outside in nice weather.

On the top floor, the original servants’ quarters have been combined to create a master suite that’s flooded with light. The historic preservation committee nixed skylights, but the McNairs have restored a glass portion of the original roof that was built over a servant’s room-cum-greenhouse. (The glass at one time was painted black and the space used as a darkroom by one of Edward Baltzley’s sons.)

A round turret room in the master suite has been transformed into a reading nook with views of the river. Given their unusual configuration, McNair and Taylor haven’t yet figured out what to do with the seven other turret rooms. “This house is art, and furnishings almost start getting in the way,” McNair says. “There are so many beautiful parts and pieces, and we don’t want to put something in that hides them.”

They continue to find creative uses for odd spaces, however. The bathroom features a walk-in medicine cabinet/closet framed by one steeply sloping eave. “Alison’s Shoe Shrine,” with multiple shoe racks, nestles under another eave nearby. A dressing table from Taylor’s grandmother sits around the corner. Taylor “grew up playing dress-up” on the heirloom.

The McNairs add to their collection of antiques with finds from Second Chance in Baltimore, Governor’s Antiques & Architectural Materials in Mechanicsville, Va., J.R.’s Antique Center in Queenstown, Md., and other places. The couple also is buying alabaster light fixtures from Germany, and they found kitchen banquette designs in London that they’ll replicate at Baltzley.

“You show pictures of Baltzley and what you’re trying to do with the restoration and people get all excited,” McNair says.

Like the Baltzleys and the Schafers before them, the McNairs are turning the house into an entertainment showcase. Last Thanksgiving, they hosted 21 people for dinner, and they recently threw a murder mystery party with a speakeasy theme for the 25th birthday of McNair’s daughter, Kari. Guests came in costume, and McNair played Al Capone.

McNair hopes to have Baltzley’s restoration complete this March, though he’ll still have to repair or replace shutters and tackle an ambitious landscaping plan. Then he’ll move on to Charles Castle.

“It’s a labor of love,” he says. “A giant jigsaw puzzle.”

He’s still learning about Baltzley, adding to his several binders of period photos and background on the castle. He has “house on the brain,” his wife says. “I didn’t anticipate living with construction workers as long as we have. It’s been kind of all-consuming, talking about it every day at the dinner table.”

The McNairs won’t share the cost of the restoration, other than to say it has been double what they budgeted.

“But where do you stop?” McNair says. “It’s been a delightful journey—an expensive, but delightful journey.”

Smart and Efficient

In 1890, Baltzley Castle was considered a model of modern design and technology, with hot and cold running water and electricity-ready fixtures. Now, owner and builder Ross McNair is ensuring that it’s a model of modernity once again.

Three geothermal wells power the heating and cooling system at the Glen Echo manse. Drawing upon the steady temperatures—roughly 55 degrees—deep in the ground, geothermal heat pumps alternately warm or cool the house and supply hot water. Even during the hottest months last summer, McNair says, his average electric bill was less than a third of what he paid in the similarly sized new house where he recently lived in Cabin John. Six thermostats control five area HVAC systems. When the construction is over and workers aren’t going in and out of the house, McNair expects the electric bills to be even lower.

A whole-house generator backs up the mechanical systems and kicks in within eight seconds of any power outage. The hot water system can work on gas if the geothermal systems can’t keep up with demand or extreme temperatures.

Stone has a good thermal efficiency rating, and at its base, the castle walls are 4 feet thick. To further insulate the upper house, where walls taper off to 18 inches, McNair used high-performance spray foam insulation in the walls and ceilings.

All appliances, heating and cooling equipment and plumbing fixtures have high ENERGY STAR ratings. And though many of the windows were returned to their original, if leaky, state to maintain the integrity of the restoration, high-efficiency windows were installed in the new kitchen area, enclosed porch and basement exercise room.

Driving the environmental considerations was McNair’s wife, Alison Taylor. As chief sustainability officer for the Americas at Siemens Corp. and an environmental lawyer, “I wanted the house to be a model of energy efficiency,” she says.

It’s a smart house today, too. The McNairs can control the HVAC, lighting, video and music systems from their iPads or smartphones. And in the master bath, a high-tech TOTO toilet features a sensor-activated lid, water-wand sprayer, warm-air dryer, user-memory settings, and other bells and whistles. Everybody “loves it,” McNair says.

Jim Mahaffie is a freelance writer living in Bethesda.