Jameson has none of the clichéd affectations of an architect. He grew up in Delmar, Md., and his Eastern Shore upbringing shows in his hard-charging character. It’s useful in his line of work, he says, because he knows how to code-switch between talking to overeducated architects and contractors he went to high school with. (“If the guys doing your floors don’t believe in your work, whew, you’re done.”) He eats at Guapo’s in Tenleytown about once a week, he says, because it’s a block from his firm’s studio and it’s a place his two kids (ages 8 and 11) can go nuts.

The most important project of Jameson’s career was his first, and it came in 1998. “I was doing this little one-car garage,” he says. “Guy was working for a company that was bought up by AOL. He bought a Volvo. He wanted a place to protect it. ‘I want a place to park my car, and I’m willing to spend $25,000 on it—that’s it,’” Jameson recalls. The architect pitched his Capitol Hill client on a private concert hall to listen to the weekly performances from the Marine Barracks a block away. “How about we focus on the in-between space between the house and the car?”

A curving, lead-coated copper wall, framed by cantilevered steel and brick, leads into the roughly 300-square-foot Meeker Garage. The project—which Jameson completed when he was 30—won eight different design awards in 1998. Other D.C.-area buildings that won in similar categories that year include the Verizon Center (then the MCI Center) and the U.S. Census Bureau’s Bowie Computer Center, both megaprojects. Perhaps even more impressively, Jameson’s renovation scheme circumnavigated the need for a D.C. zoning hearing for lot coverage while also meeting Capitol Hill Preservation Board requirements.

Architect David Haresign, who met Jameson back when he first completed the Meeker Garage (“a terrific little project”), says that Jameson now ranks as one of the three best contemporary residential architects working in D.C. (The other two, he says, are Bob Gurney and Mark McInturff—architects whose names come up in conversation with Jameson.) Haresign, who just finished a term as the president of the D.C. chapter of the American Institute of Architects, compares Jameson’s work to good bourbon. “He’s a distiller. He captures the key ideas,” Haresign says. “He’s so skilled at it that he’s sought out.”

Fifteen years ago, though, no one expected small-batch, craft-quality work from Jameson, except maybe Jameson himself. After graduating from the five-year architecture program at Virginia Tech, where he attended school on a baseball scholarship, Jameson wormed his way into D.C.’s noblest architectural tradition. He had already been rejected twice by Hugh Newell Jacobsen’s firm when he slipped the architect his portfolio while getting a book signed—and told him he’d work for free. Jameson got the (paying) job.

Jameson “is a risk-taker,” Haresign says. “He’s a larger-than-life kind of guy. He’s a good thinker, and a talker.”

Jacobsen was a D.C. legend who had designed scores of homes, especially around Georgetown, when Jameson started working for him. He had presided over the renovations of the Smithsonian Institution’s Arts and Industries Museum and Renwick Gallery, as well as the Capitol’s West Terrace.

“Hugh [Jacobsen] was the successor to Charles Goodman,” says Gregg Bleam, a Charlottesville, Va.–based landscape architect who has worked with David Jameson Architects since 2001. Goodman set the bar for postwar D.C., designing the original National Airport as well as the aluminum-clad River Park Mutual Homes complex in Southwest. Bleam (himself a protégé of the great landscape architect Dan Kiley) says Jameson wanted to be the next singular voice in D.C. architecture.

Jameson’s apprenticeship ended in 1996, at a time when Washington-area houses were growing wildly in size but not especially in stylistic scope. “I started the practice with building what I would call closet modernist projects, these jewel-box additions to colonial houses—these things where the face of the project still had a mannerism geared toward yesteryear,” Jameson says. Following his unlikely breakthrough, he launched David Jameson Architect Inc. in Alexandria in 2001.

“I grew up in a family of architects, I’m not an easy test to pass, and he is one of the best,” says art dealer George Hemphill, who hired Jameson to design his 14th Street NW gallery in 2004. “Galleries are tools for the presentation of and selling of art,” Hemphill says. “Over my 40 years of working in galleries, this is the best tool I have had the pleasure of using.”

The two have frequently traded clients. Hemphill artists like Steve Kushner and Robin Rose have done five-figure commissions for Jameson’s homes. Hemphill once sent a collector looking for a kitchen renovation Jameson’s way; the architect wound up designing a new, 3,500-square-foot home for her: the Dahlonega Residence in Bethesda, which won several regional design awards last year.

Jameson has a collection of accolades like these. He was the youngest architect to appear in Architectural Digest’s roster of the world’s 100 best architects and designers in 2010. The London-based magazine Wallpaper named David Jameson Architects as one of four emerging U.S. talents to watch in 2011. And the Wall Street Journal has described him as one of the two best residential architects on the East Coast and one of 10 best house designers nationwide.

Success hasn’t gone to his head, either. “He is more mature, whatever that means,” Haresign says. He says that Jameson is a bolder architect now, in terms of how he uses design and technology. (And even color. “His palettes are richer and his spaces are getting warmer and more humane.”) Hemphill, too, says that Jameson lacks the stereotypical “round-spectacled pretense” and praises his “relaxed and natural manner.”

Easygoing is more like it. But while he may be a casual guy, he is a devout technocrat. Piles of new materials are stacked up against every wall in his firm’s studio. His own home in Bethesda is something of a workshop. “I like the process of exploring new ideas in my house,” Jameson says. “I had an idea about coplanar windows and sliding doors, so we invented them with a custom window company. I had an idea about the façade system, and we invented something never seen before.”

Success hasn’t exploded his firm. “This is the smallest firm I’ve ever worked at,” says Alex Wojno, a designer who joined the firm two years ago, just before it moved from Alexandria to the fourth floor of a fairly nondescript building near the Tenleytown Metro station. The firm employs 10 people, some of whom work part-time on specialized tasks like lighting or 3D modeling.

“Everyone here is in charge of their own projects, from concept to construction,” Wojno says. In some ways, the firm is still country. Wojno’s thesis drawings hang on the wall, adding to a generalized clutter; while she was still finishing her graduate degree, her colleagues served as her unofficial advisors. But it’s metropolitan, too: Jameson’s architects hail from some of the best ateliers on the planet, including OMA (the firm founded by Rem Koolhaas) and Peter Zumthor (the architect tapped to reset the campus for the Los Angeles County Museum of Art).

Yet it’s also classic: Jameson wants to bring on an in-house structural engineer, he says, because he is a student of Louis Khan’s studio and Frank Lloyd Wright’s studio, and that’s the way they did it. “You work with every kind of consultant you could ever work with,” Wojno says.

When I visit over lunch one day, the staff has picked up Crisp & Juicy on Jameson’s dime. It’s a studio quid-pro-quo: He buys them lunch, they sit through a seminar on Revit (a building information modeling software).

“I’m sitting here in a sweatshirt with a hood on it and sneakers on,” Jameson says. “It’s not really different from a studio at MIT. Architecture can be art—yes, it has to meet budget, yes, it has to meet program, yes, it has to meet historic preservation review—but it can still be art.”

One thing that David Jameson Architects is not: a house of style. Neither his clients nor his colleagues align him with any particular movement or ideology (beyond modernist). Jameson waves off the question. “We’re bringing a set of principles to play instead of a style,” he says. “I’d love to believe the style isn’t any evident in any manner. We’re Janus-faced! Like the Roman god. Looking forward but also looking to the past.”

“Who do you think when you think classic D.C. rowhouse? Harry Wardman,” Jameson says, as we pull plastic booties over our shoes to tour the interior of the Slot House. “Harry Wardman always used heart pine floors. That was the bespoke wood of the day.”

Long, uninterrupted beams of heart pine fitted perfectly to the space compose the floors of the Ontario Place house. Inside, at a perpendicular to the ground plane, Jameson has designed a vertical void—one where he’s built “a column of light, but also a column of darkness.” While light streams down from a skylight above, a multiton blackened steel stair with trapezoidal winding rails and perforated steel mesh steps rises up from below. This column of darkness is also a column of brightness: The perforated metal steps feel lightweight, and it’s possible to see through them to floors above and below.

“Other architects depend on painterly devices to get there, where David works from the purity of the diagram,” Bleam says. “Volumetrically, what he does is what makes the work.”

One way to describe Jameson’s work is in the way he arranges volumes. For the NaCL House in Bethesda, the firm arranged various rooms and cubic masses to resemble an outcropping of rock salt. Many of the forms appear to hover just off the ground. The Graticule House in Great Falls, Va., features an upper wall that serves to cover an outdoor terrace—though it appears as if it’s a slice of a room that has been left suspended while the rest was removed.

Jameson’s best-known built project within the District is the Barcode House, a townhouse addition near Dupont Circle on 18th Street NW between Riggs and S streets. The design appears to remove one wall of the home entirely, replacing it with glass panels rising two stories and intersected by steel bars that form a vertical barcode.

“He doesn’t compromise his vision, but he’s able to adjust it in a way that you are pleased,” says William Agosto, who owns the Barcode House with his husband. The project called for a third of the house (a previous addition) to be removed and rebuilt. Jameson confined the project to the existing perimeter of the legally permitted addition, making it a “replacement in kind”—meaning the project didn’t require a public hearing for another permit because it wasn’t adding any volume.

The Barcode House bypassed Dupont Circle’s notorious NIMBYs because Jameson routed around them. (Jameson’s colleagues in architecture say they admire his use of new technologies; his clients praise him for cutting the red tape.) But Agosto—who says he waves back when people wave to him through the transparent glass walls of his home—thinks it was never likely to be a problem.

“Without mimicking the past, he’s able to create something that fits well within the neighborhood or in the house. Continuing certain lines, following certain patterns,” Agosto says.

None of Jameson’s homes refers architecturally to the others—or to the BlackWhite Residence, or the Tea House, or the Jigsaw Residence, or the Matryoshka Residence (or to the growing roster of the firm’s projects outside the area, flung as far and wide as Southern California and Hanoi). And none of these homes is bound to resemble the McMillan project, whatever name that eventually takes.

“The developer wanted someone who would push the envelope,” says Anne Corbett, project director for Envision McMillan. For the multifamily project, Jameson is collaborating with MV&A, the firm that designed the mixed-use building anchored by a Walmart at 1st and H streets NW. “There wasn’t an architectural firm with the technical expertise who would push the envelope from a design standpoint. Obviously, this kind of building is not in David’s normal wheelhouse. Pushing the design envelope certainly is.”

While he has yet to release detailed designs, Jameson says that he is collaborating on the façade system with Bill Zahner, the Kansas City, Mo.–based machinist who has worked with Frank Gehry to execute most of that architect’s titanium tapestries. (That doesn’t mean he plans to drape twisted metal over the apartment building—he’d have more groups than Save McMillan Park after him if he did.) Jameson will say that the metalwork for the façade, which appear in renderings to be a series of fins, will be a specific callout to the site’s history as a sand-filtration site.

“He kind of took apart the DNA of the site,” Corbett says. “I think his process was good for the team as a whole, pushing the other architects to think a little bit differently about how they responded to the site.” Jameson’s involvement on the McMillan project may not be limited to one building, she notes; phase two calls for another mixed-use building, and while the work hasn’t been contracted yet, she says there’s no reason to think Jameson won’t be involved.

“We got the McMillan project because the process of the work is scalable. For many residential architects, it’s difficult to move from small to big or from inexpensive to expensive,” Jameson says. “But none of those things matter to scaling my work.”

There’s still a staggering number of hurdles for Envision McMillan to overcome before the design becomes a reality. The project cleared one by winning the approval of the Historic Preservation Review Board in October. Envision McMillan will come before the Zoning Commission in several public hearings in late April or early May. Then, with those recommendations appended, the plan goes before the Mayor’s Agent, who is involved because the project requires demolition to adapt the landmark.

One of the biggest battles has already been won: persuading a developer to invest in the design aspect of a mixed-use building plan.

“It’s almost like the World’s Fair in Chicago,” Jameson says. “It will be a slightly different thing than anything else in Chicago.”

Jameson spent the Super Bowl in Fayetteville, Ark., where he traveled to give a talk for a lecture series at the University of Arkansas school of architecture. Other speakers in the school’s 2013–14 lineup include Tod Williams and Billie Tsien, the architects who designed the new Barnes Foundation in Philadelphia, and Peter Eisenman, the architect and theorist who designed Berlin’s Holocaust Memorial.

“I was begging Marlon Blackwell to get me out of there before the ice storm did me in,” Jameson says. (Blackwell is Arkansas’ best-known architect.) “We’re watching the Broncos get pounced, and Marlon says, ‘We’re just in this totally challenged ZIP code.’ I’m like, what are you talking about? You’re doing the architecture school, the local high school, you’ve got all the major players. I feel like I’m ZIP code challenged,” Jameson says.

That hasn’t always been the case. “When the real-estate boom hit, the value of land eclipsed the value of building. That was huge for me. I was able to go quite quickly from small additions to large additions that looked like new houses—to new houses,” he says. “And those houses became the paradigm of habitable art.”

Today it’s that wealth that sets D.C. apart. Census data for 2010 put median household income for the D.C. region at $84,523, making it the highest-income region in the nation. Fayetteville, where Blackwell toils alone, pulls in an estimated median household income of $34,393.

The downside to D.C. ZIP codes is that clients think more and more that the only ones that matter are elsewhere—and mostly in New York. All three firms shortlisted by Catholic University to design an addition for the Edward M. Crough Center for Architectural Studies, for example, are boutique firms from northeast of here (Architecture Research Office, Lewis.Tsurumaki.Lewis, and Gray Organschi Architecture). D.C. architects aren’t likely to make the cut when a cultural organization needs a name it can fundraise against.

“Look at the Richard Meier high-rise in New York,” Jameson says. “The closest thing that’s being built today [in D.C.] is the Foster + Partners project at CityCenter. And even that’s safe.”

Another challenge for architects with D.C. ZIP codes is that there are too many of them.

“There’s a shitload of architects in D.C. There’s more architecture firms here than in L.A. or Chicago. Think about Chicago: How many firms are really kicking ass in Chicago? There’s one or two or three,” Jameson says. He pauses. “Why is it my studio is thought of as this singular voice for architecture in the city? That’s the question we try to answer in the studio. I want to believe the answer is: We’re just doing really compelling work.”

D.C. architects face local competition from some of the largest firms in the world, which all keep offices in Washington for the sheer amount of work the federal government produces. It’s scratch for a major design corporation, like AECOM or HOK or Gensler or Perkins+Will—all of which have D.C. offices—to do work in town on a pro-bono basis that a smaller firm might want for its portfolio (and to make a living).

“There’s a layering of firms that only do development, only do government, only do transportation work,” Jameson says. “Having a firm that is a generalist and wanting to do everything, it’s challenging in that respect.”

“As a contemporary architect, [Jameson]’s had the good fortune to be on the bleeding edge of contemporary architecture,” Haresign says. He takes the long view that architecture in D.C. has been steadily improving since the 1970s, beginning with I.M. Pei’s design for the East Wing of the National Gallery of Art. Bland multifamily buildings don’t contradict that overall trend, in his opinion. “The quality of architecture in D.C. has been on an upward trajectory. David’s a strong leader in that regard.”

Nevertheless, Jameson’s involvement with Envision McMillan is an encouraging prospect—especially given that the surge in economic growth in D.C. has been met by such dreary design. Tedious condo buildings have choked 14th Street NW and other corridors in the last five years. Perhaps one new building with some design acumen will encourage developers to reconsider aesthetics as a strategy for creating investment opportunities.

There are signs that this is happening elsewhere. David Adjaye, the London star designing the National Museum of African American History and Culture on the National Mall, is converting the West Heating Plant into high-end condos for Georgetown, where the famed Mexican firm Ten Arquitectos is designing the West End Library. What Envision McMillan will test is whether compelling design from D.C. can be brought to bear on projects nowhere near 20037.

And if the answer’s yes, then it means D.C. might soon enjoy more of the approach to mass and space and volume that is winning Jameson renown outside the District.

“I’d love to see a greater emphasis on actual place-making and design itself in D.C.,” Jameson says. “I came to D.C. in 1991. I’ve been here for 25 years this year. This is a place where architecture has always been imported to. I’d love to see that change.”