After years of being supported mainly by do-it-yourselfers and buyers concerned with energy efficiency, the quietly growing log home industry has found a new source of strength: Young people who simply like the way log homes look.

An independent poll of 486 people among thousands attending log home seminars across the country -- extra chairs were needed for the overflow crowd at a recent seminar near Dulles Airport -- confirmed the changing profile.

Half of the prospective homeowners were under 40, with college degrees and yearly incomes of $30,000 to $50,000.

The shift comes at a time of overall change for makers of log houses, sales of which are expected to soar above the current 25,000 a year -- 7.6 percent of the custom-built home market. Among the developments:

The high-tech descendants of old-time log cabins are better insulated than ever, and the energy efficiency claims have been proven in government tests.

The industry, dominated by small companies that rarely top 50 homes a year, is becoming better understood by bankers.

John Kupferer of the North American Log Home Information Center in Herndon explained that most log companies want payment in full when they drop off the logs, but banks dole out construction loans in drafts.

"When they see the foundation up, they'll pay for the foundation. When they see the subfloor in, they'll pay for that. All the way up they have a regular set schedule. They don't want to make exceptions to that schedule," Kupferer said.

"We come along with a load of logs and say we want our money, and the bank says when it's up, when it's real estate, they'll give you money for it. When it's building materials, you've got to buy it," he said.

The snag is being overcome in a variety of ways, most often with commitment letters to have the home erected in 30 days. Some companies eliminate the problem by building the house as well.

The marketing is also becoming slicker, with layaway plans and fancy brochures. Most offer custom-design services and complete blueprints.

Young professionals are not the only ones buying log homes. People trained in technical or blue-collar trades made up 15 percent of the crowd, and most were interested in the sweat-equity aspects of building their own homes.

Energy efficiency ranked sixth as a reason for interest in a log home, according to the seminar poll, but it still draws thousands of potential buyers.

Wood gets its insulating qualities from the tiny cells and air pockets inside, but the real energy gain comes from its sheer mass.

The logs are heavy enough to absorb heat and release it slowly over time. In the summer, the process reverses and helps lower cooling bills.

Thicker, more massive logs have a greater thermal capacity, but eventually the increased cost of giant logs outstrips energy savings.

The size of the logs, both in length and width, is a key factor in the widely varying prices of log homes today.

Another big cost factor is whether the logs are hand-hewn -- hacked with an axe and trimmed with draw-knives -- or machine milled.

The type of wood plays a role, but the most important variable is how much is included in the kit package.

Some companies offer nothing but logs; others supply windows, doors, shingles, subfloors and the like.

The poll found log home buyers to be surprisingly well-informed shoppers.

A full one-third contacted more than five companies before buying. Half bought three catalogues or more, and half were planning more than a year ahead.

The research also found that 31 percent plan to be their own general contractors and 38 percent have a complete floor plan figured out by the time they decide to buy a home. Two-thirds of the time the home is bigger than 1,500 square feet; 28 percent exceed 2,000 square feet.

Depending on how much work log home owners do themselves, the cost remains comparable to conventional homes -- $45 to $55 a square foot.

When looking at prices in catalogues, the rule of thumb is that the final cost will be twice the kit price.

That's because of costs for such items as grading and excavation, basements and foundations.

There is a wide array of building options, especially on how the corners fit together, and there's a pretty even split when it comes to homes being built log-on-log or with walls where chinking is stuffed in the cracks.

The poll also showed that 62 percent of all potential log home buyers already own a home. The center's Shanna Shepperd said log homes are becoming an integral part of what real estate agents call the "move-up market," of people moving out of starter homes.