BLACKSBURG -- It's verboten for any of the designers who worked on Carol Crawford Smith's house to talk publicly about what she will encounter when she is escorted through her new front door Sunday by "Extreme Makeover: Home Edition" star Ty Pennington.

But at least parts of the new home will borrow from Virginia Tech's solar house, which made a good showing at a national competition in October.

Smith, a single mother of two boys who suffers from multiple sclerosis, was chosen this fall from thousands of applicants to get a new house from the ABC reality TV show.

"Extreme Makeover: Home Edition" has about 20 million viewers, producers say, and is now building about four houses per month in its third season. Thousands of families apply to the show each week, hoping their story of need will move the producers to build them a new house.

When ABC chooses a family, the producers contract with a local or regional builder that manages the project and solicits donations of materials and labor from local and national companies.

Building Specialists of Roanoke was chosen as the general contractor for the Smith family house and has worked with dozens of other contractors and companies and with Virginia Tech's architecture department since October to design and now build the house.

The university team is made up mostly of the same faculty and students who designed and built Tech's solar house, which captured top honors for architecture and livability in the 2005 Solar Decathlon in Washington, D.C.

Joe Wheeler, one of the Tech faculty members, gave up his Thanksgiving vacation to put in long nights with colleague Bob Dunay and a team of students on the Extreme Makeover project.

The Tech team worked closely with Amanda McCreary of Building Specialists, one of Dunay's former students, to come up with the design.

The challenge: Design a totally handicapped-accessible house from scratch in two weeks. Oh, and it also had to be able to be built, start to finish, in about 107 hours.

The design is meant to make it easier for Smith and her two sons, Hunter and Garland, to spend time together while also providing private spaces for them, Wheeler said.

But the Tech team is most excited about a special project they're working on independently -- a meditation and reflection room that will be attached to the house.

That room will have specially insulated walls that glow with light and color to make it an inviting place for Smith, a former world-class dancer who now has trouble walking, to exercise or meditate.

To build it, the team solicited donations from local businesses such as Heavener Hardware, which has given about $2,000 in materials to the effort, Wheeler said.

The short schedule was the biggest challenge for McCreary because there was no time to mull over details, she said.

The biggest challenge for the Tech team, according to Wheeler, was juggling the demands of ABC's TV crew, which needs good camera angles and a lot of national product placements, with the long-term needs of the Smith family.

The team also wrestled with the size of the house, the value of which will ultimately increase Smith's yearly tax and utility bills and homeowners insurance costs.

Extreme Makeover has constructed houses as big as 6,000 square feet for some families.

Smith paid about $144,000 for her old house in 2002. Estimated retail value of the new house is about $400,000, Dunay said.

To offset some of those future costs, Building Specialists has set up an account for the Smith family and is asking for donations.