All Kevin Middleton wants is a roof by Thanksgiving.

"We'll get it done," he murmured, scanning blueprints for the 2,252-square-foot house. "We will get it done."

Middleton, the no-nonsense site manager for Thomas Edison High School's home-building program, was trying not to panic. But as he surveyed the construction site, he could already tell: He'd need a big bottle of aspirin to get through the next couple of weeks.

His crew -- two dozen teenagers -- was six weeks behind schedule, and some still didn't know their tail beams from their trusses. Their deadline is unforgiving: By May, the students have to build a three-bedroom, two-bath house with a spa-style bathtub and detached garage on a scenic stretch of Connecticut Avenue in Silver Spring.

It could sell for $500,000.

For more than two decades, students in Montgomery County have been the force behind a multimillion-dollar real estate venture. Since 1976, they have built and sold more than 30 houses, with the profits used to buy land and materials and to hire professional subcontractors for future projects. Although Middleton is based at Edison, his workers come from schools throughout the county.

Montgomery's program is one of several in the area and across the country through which teenagers learn construction by doing it. Fairfax County students built a $1 million house in McLean in 2003, and another group has been working for two years on a 6,300-square-foot house that will be priced about $2 million when it hits the market in February.

In Arizona and Ohio, students donate houses they build to Habitat for Humanity. In Montgomery, last year's house was listed at $479,000 but sold for $586,000 -- a record for the program.

This year, under the watch of Middleton, a former construction industry executive, and their teachers -- specialists in carpentry, masonry, plumbing, landscaping and heating and air conditioning -- the students will finish building the house over the next six months. They will frame the walls, install the plumbing and run the cables and wires that will make the lights go on and off.

Already, they've endured a frustrating string of delays. First there was a countywide slowdown on permits stemming from the Clarksburg controversy. Hurricane Katrina then threatened their lumber supply before October rains virtually confined them to inside work.

None of it has dampened their enthusiasm.

"It's great just going out to the site every day," said Paul Trevey, 16, a senior at Sherwood High School in Sandy Spring. "I like the hands-on stuff."

Shepherd and Teacher

Middleton's official title is coordinator, which hardly conveys what goes into running a construction site where the stepladders outweigh some of the workers and where crew members have to be reminded to stop leaving their sweat shirts lying around.

Last year, when the teenagers built a house adjacent to the current site, time was their friend. Everything was ahead of schedule -- from permit approval and pouring of the foundation to the final placement of the roof.

This year, fate turned on them.

By the time Mykal Vasquez, 18, hammered the first nail into the back wall Oct. 12, the students were a month behind.

Don Wheatley, the carpentry teacher at Edison, could only growl in frustration one recent day as he looked over the header that students had built to go over a back door. He thought he'd explained the concept clearly in class. They had looked at illustrations in a textbook and discussed the technique.

But the students hammered too many nails too close together, causing the wood frame to split -- hardly what would be wanted for something that's supposed to help support the second floor.

The piece had to be pulled apart and redone. Lesson learned, but 45 minutes of precious construction time lost.

Some days on the site, it seems, every step forward is followed by two steps back. For every nail the students pound in, it seems, they pull out three. Their teachers say it's all part of learning what it takes to make it in the building industry.

With a full-time, experienced crew, a professional builder could throw this house up in four, maybe five months. On a good day, the students -- one group working mornings, another afternoons -- are able to devote 180 minutes to the house.

The roof is an important milestone; Middleton wants it in place before the weather turns bad. Once the roof is on, students can store their supplies inside and work regardless of rain or snow. Then students in the plumbing, heating and air-conditioning and decorating programs can start their work.

A roof by Thanksgiving, Middleton said, is critical if they are to make up for time lost. It will be close. Laying the first-floor base took eight days; putting up the walls took five.

Middleton had planned to have his permits in hand and the foundation poured long before classes began Aug. 29. While the student builders were doing their safety training, he'd be getting the steel support beams set for the first-floor base.

What he and others didn't plan for was Clarksburg. Blueprints for the student-built house were submitted a few months after numerous planning violations were uncovered at Clarksburg Town Center, at the opposite end of the county. The additional scrutiny lengthened the process.

In a normal year, the student builders would have had their building permit by early August. This year, it was issued Sept. 15.

Then Hurricane Katrina hit the Gulf Coast as classes began in Montgomery. The building instructors began to worry about the effect on their lumber supply. Some quick phone calls found only 300 plywood sheets in the Washington area that fit their specifications. Their project alone would require 120 sheets.

After some begging and negotiation, they got what they needed.

The October rains cost them more time. Instead of being at the site, students were stuck in their classrooms reading about how to frame a house. When they finally got out, they spent more time shoveling thick mud out of the basement than building anything.

Now, every day, they study the weather forecast.

Hitting Their Stride

On a recent Thursday, it was cold and windy. The day's tasks were to put the kitchen wall in place and to erect the second-floor support beam. These were big, critical jobs.

Midway through the work period, it didn't look good. One crew struggled to get the nails in straight. In another corner, metal brackets for the floorboards were nailed in straight -- but upside down. Wheatley's optimism wavered.

"Well, maybe we won't get the beam set after all," the carpentry teacher said.

But suddenly the students found their groove. The nails started going in straight. Metal supports were pulled off and redone. Hammers flew, and walls went up.

With seven minutes to go before they had to board a bus back to school, the two instructors and 12 students hoisted the beam. A few minutes later, it was in place. Middleton was that much closer to getting his roof for Thanksgiving.

Zack Calandro celebrates after he and his fellow Montgomery County student-builders got a large crossbeam in place in less than two hours. Kevin Middleton, right, site manager for Thomas Edison High School's home-building program, gives Mark Roseman some carpentry tips at their construction site on Connecticut Avenue in Silver Spring.Student builders work on the three-bedroom, two-bath Silver Spring house that they must finish by May. Their instructor's hope is that they'll have a roof in place by Thanksgiving.Luis Thomas, 19, part of the two dozen-member teenage work crew of Montgomery County students, carries a prefabricated joist.