So you need more space in your rambler, bungalow or split-level house, but you don't have room to bump out the back?

Consider building up, instead.

"Pop-ups," or pop-tops, or just plain second-story additions, are renovations that add height rather than girth to a house. And they're gaining in popularity in the Washington region, an area full of older, smaller homes just ripe for flipping their lids.

There are no statistics that track this type of renovation, but local remodelers report a surge. "It's almost everything we do," said Troy Fenley, partner in Encompass Design/Build of Vienna. "A lot of our customers are in small one-story houses. They want a second floor. They want more room. They want to update their lifestyles."

A pop-up renovation involves adding a second story onto a house or upgrading a substandard second floor, such as a crawl space or a low-ceilinged attic. It's most common for a single-level rambler, transforming it into a sorta-Colonial. Homeowners are also popping up older split-levels and bungalows.

"By definition, a rambler is the house you pop up," said Mark Scott, principal with Mark IV Builders in Bethesda, who has been doing these additions locally for about a dozen years. "But the split-level is actually the easier pop. With a split, there are fewer options than there are with a rambler. You pop up right over the living room-dining room-kitchen."

Whatever the style of the original house, popping it up involves more than just putting a new story atop it. For a successful update, the old house and the new addition should be blended to achieve a cohesive look inside and out.

"Not doing anything to the first floor almost never works," Scott said. "Then you're left with a house on top of another house. That's not good design."

Fenley said: "There are structural issues, too. You're adding a whole lot more weight and load to the existing footings. You may have to underpin the first-floor foundation because of the extra weight, in addition to the aesthetics."

Bigger Bedrooms

Many owners use the new second floor for bedroom space. It can become a single large master bedroom suite, with walk-in closets, a large master bathroom and a separate office. Or it can be two or three bedrooms and bathrooms.

The existing ground floor becomes a larger common living space. By incorporating one or two old bedrooms and the old hallway into a new layout, it's possible to create a bigger kitchen or a kitchen-family room-dining room combination.

Often, a pop-up renovation is done along with a small bump-out in the back of the house to accommodate that large kitchen-family room. The old bedrooms become studies, closets, powder rooms or part of the new stairway going upstairs.

Sometimes homeowners, particularly older ones, decide on a master bedroom suite on the first floor. In that configuration, all three of the small bedrooms in a typical 1950s rambler, and the long corridor they connect to, can become one big bedroom suite. Bedrooms for grandchildren or guests go upstairs.

One of the trickiest design considerations in a pop-up renovation is where to put the new stairway that leads to the new second floor.

"The fact that you need a new stairwell forces you to modify rooms on the first floor," said Gaver Nichols of Gaver Nichols Architect in Alexandria, whose renovation work is about a quarter pop-ups. "The long hallway in a rambler can become part of the new stairwell."

Encompass Design/Build's Fenley said: "The new stairway usually takes up an existing room, or part of a closet, or part of a bedroom on the first floor."

A well-done pop-up integrates the old and new exteriors. That can mean matching new brick to existing brick, or painting all the brick to match. Homeowners often choose siding for the new second story to avoid brick-matching mistakes. Or they might re-side the entire house. Trim and windows also should match.

"The idea that you'll just pop the top and leave it isn't realistic," Mark IV Builders' Scott said. "You have to carry the design through the entire house."

Often, how the new two-story structure blends with its neighbors is another consideration. By their nature, many pop-ups are done in older neighborhoods where similar houses sit relatively close together.

"We really didn't want our house to stick out," said Lynn Trane of the rambler she and her husband popped up in Chevy Chase. "A lot of people around us are not planning on changing their houses. So we wanted to be sure our house still matched everyone else's."

Instead of adding a full second story on top of their rambler, the couple chose half of a new story set back on the roof of their house. As a result, the house is most obviously two stories when viewed from the rear, where it backs to Rock Creek Park. From the street, the change is more subtle.

Pop-ups aren't cheap, usually running in the hundreds of thousands of dollars. Local remodelers say pop-ups cost $200 a square foot or more, depending on the fixtures and fittings the homeowners choose and on how extensively the ground floor is changed.

Although a pop-up may initially seem less expensive than a pop-out renovation of the same size because it's built on the existing foundation, reconfiguring the existing space and blending the new with the old brings the price back up, remodelers say.

"For people thinking about doing a pop-top, they might want to consider knocking the whole house down and starting over instead," said architect/builder Nichols. "Sometimes it's cheaper."

But most candidates for popper-uppers like their houses. They just want them bigger and better.

"I never considered tearing my house down," said Melissa Fife, who recently popped up her 1925 bungalow in Alexandria, spending about $400,000. "That's sacrilege. We bought this house in this neighborhood because of the sense of history here. That's what we love about it."

Here is a closer look at three local pop-ups:

Redoing a Rambler

Retirees Peter and Jo Piraneo might not seem to be prime candidates for a pop-up renovation. The couple, who are in their seventies, were living in a Colonial-style house in Fairfax when they decided it was time to switch to single-level living. But they wanted roomy single-level living.

"What we wanted doesn't exist anymore," Peter Piraneo said.

"All the houses were old and small," Jo Piraneo said.

First they tried to find a newly built rambler, but that proved a problem.

Ramblers take up more land than Colonials -- they generally require three-quarters of an acre to a Colonial's half-acre. Land prices in the Washington area have soared over the past few years, making a rambler's base cost significantly higher than that of a two-story house. So production builders generally aren't constructing them.

The couple then searched for a big lot where they could have a rambler custom built.

"All the lots we saw were either too small or they were oddly shaped," Jo Piraneo said. "We didn't see one lot that could have worked for us."

Finally, their daughter suggested buying an older house and remodeling it to suit their needs. They found a 1955 rambler near the Potomac River in Mount Vernon, close to where their daughter lives.

It was one story, but the three bedrooms were tiny, and the home had only 1.5 bathrooms.

"I wanted to knock it down and start over, but our architect talked us out of it," Jo Piraneo said. "He said the house was built very solidly and that we couldn't duplicate some of its features, like the rafters. He said we could make it into what we wanted."

And so that's what they did.

Even though they were searching for one-level living, the couple popped up a second story. There, they have added two bedrooms and a bathroom for their granddaughters, who visit regularly.

The Piraneos mostly live downstairs. The rambler's original three bedrooms and 1.5 baths have become the master bedroom suite, which includes two walk-in closets and a master bathroom.

The back of the house was bumped out to create a large great room off their new kitchen, as well as a screened-in porch. The second floor looks out over the great room from a loft area.

The couple also re-did the front of the house, creating a more welcoming entrance. They converted the existing garage to living space and built another two-car garage.

So in addition to the kitchen, family room and master bedroom suite, the ground floor has an office, a library, a new entrance foyer, a powder room and a breakfast area -- the sprawling single-level space the couple wanted.

"We spend 99 percent of our time on the one level," said Peter Piraneo. "We put the second story in for the grandkids, when they want to spend the night, and for resale value."

On the outside, the Piraneos went with a natural cedar shake siding for the second story and the new areas of the house. They retained sections of the original brickwork.

Rather than a single long roof line, the roof comes to two gables on the front, vaguely reminiscent of a Cape Cod. A four-columned portico adorns the front of the house.

The Piraneos transformed their dated rambler into a three-story (including the original basement), five-bedroom, 3.5-bath home. The extensive renovation cost them $480,000. They stayed in their old house in Fairfax while the work was being done.

"We are just so pleased with it," said Peter Piraneo.

"This is our final home," Jo Piraneo said.

Maintaining Character

Melissa and Terry Fife fell in love with their little Alexandria bungalow when they first saw it in 1999.

It's a Sears house, one of the mail-order homes Sears, Roebuck & Co. shipped out by rail in the early 20th century, with parts numbered for easy assembly. It sits on a tidy tree-lined street of similar bungalows and little brick houses with front porches in the Rosemont neighborhood, in the shadow of the Masonic Temple.

For a while, even though the house had just three bedrooms and one bath, it worked for the young couple. But as their family grew, space became tight.

"It was only 1,100 square feet with one bathroom," Terry Fife said. "It was a pretty small house."

The lot the house sat on was also small, so options for spreading out were limited. And the Fifes liked the character of the house and didn't want to alter it much.

"Those were the challenges," Terry Fife said. "We wanted to maximize the space without going overboard. We wanted a bigger house, but we still wanted to maintain the integrity of the house and keep it in the style of the neighborhood."

So they decided to expand mostly up -- with just a bit out back.

The house had an attic that was 61/2-feet tall at its highest point. The couple expanded that substandard second floor into a full second story. There they added a master bedroom, a master bathroom and a bedroom for their daughter.

Downstairs, the inside space was kept almost as it was except for the bump-out in the back, which became a great room off the kitchen.

Outside, the new second story comes to a gable that echoes a gable on the side of the front porch. Originally, the bungalow's roof had a single gable.

The four-column front porch, with its white railing, was maintained, as were the four front windows on the first floor.

The couple put wood siding on the new addition and then re-painted the entire house charcoal gray. The new double-hung windows on the top floor are of a consistent design with the old windows, although not identical.

The Fifes moved out of their house for several months after a fire there, which was unrelated to the renovation but slowed work considerably. "The whole process was inordinately difficult," Melissa Fife admits, "but we can't get over the space we have now."

She also believes the house has retained its historic character. "It's much, much taller, but it still looks like a bungalow," she said. "It's definitely not a Colonial. It's more stately than it used to be."

Popping Up and Out

Lynn Trane and her husband, Sidney Smith III, like their back yard, a big, flat space that backs onto woodland. They put a large playground set back there for their two toddlers; it doesn't take up much of the space.

But the house itself, a Chevy Chase rambler built in 1951, was just too small for their family. The couple yearned especially for a real master bedroom, an area that could be their own private sanctuary.

So they popped the house up -- and a little bit out.

"We would have had to take up our entire back yard if we had only gone out," Trane said, "and we wanted to keep the back yard for the kids to play. Popping up made a lot more sense for us."

Their new second floor is a master bedroom suite -- a huge bedroom; a big master bathroom with a separate double shower, whirlpool tub and double vanity; an ample walk-in closet; and a separate office for Smith. There is a little balcony off the bedroom and a lot of windows that look out over the woods.

Downstairs, they bumped their house out enough for a kitchen-family room combination. They lost part of their flagstone patio, but none of their yard.

They kept the old downstairs bathroom and two of the old bedrooms, which have become the kids' rooms. One bedroom was eliminated and made into a hallway and powder room.

The stairway leading upstairs is where the old kitchen used to be.

"First, they put the stairs on top of the stairs to the basement," Trane said. "But they were in a weird area that wasn't working for me. Now, they're against the wall, which is much better."

The family remained in the house during the three-plus months of renovation -- and say it wasn't that bad.

"At one point, the house was tarped," Trane said. "But they worked fast."

She added: "I didn't have a kitchen for the full three months. But I don't cook, so it wasn't that big of a deal. As long as I have a microwave and refrigerator, I'm set."

One of the big considerations for the couple was that their house would continue to blend in on their street of modest ramblers. So they set the second story toward the back of the roof.

"The roof-line is changed, but since we're on the top of a hill, you can't see it that much," Trane said. "From the road, it still looks like a rambler."

Outside, the couple matched brick on the lower section. They used vinyl siding on the second floor.

They're ecstatic about their $380,000 renovation and say they never considered tearing down the house.

"There was no need," said Trane. "We liked the basic design of the house. And the basement was already finished. We just needed more living space."

She said they're happy that they got what they wanted without having to give up their beloved yard.

"It feels like a brand new house," she said. "It couldn't have happened without popping up."

In Fairfax, Peter and Jo Piraneo transformed their rambler, which had three small bedrooms and 11/2 bathrooms, into a three-story -- including the original basement -- shingled house. After the renovation, the new master bedroom suite included two walk-in closets and a master bathroom. BeforeAfterIn Alexandria, Melissa and Terry Fife's bungalow had three bedrooms and one bath. They expanded the attic into a full second story, adding a master bedroom and bath, and a bedroom for their daughter. BeforeAfterIn Chevy Chase, Lynn Trane and Sidney Smith's rambler, at left viewed from the back yard, has almost doubled in size with, a second story and an extension. The second floor is a master bedroom suite. BeforeAfterMelissa Fife plays with her daughter, Barrett, in front of their house in the Rosemont neighborhood of Alexandria.