When David Stiles and his wife, Jeanie, wrote "Tree Houses You Can Actually Build," they ran a small newspaper ad to find treehouses near their Long Island home.
"Just in the small town of East Hampton we were contacted by about 20 or 30, and those are just the ones we found," says Mr. Stiles, a designer, builder, and illustrator. "There must be 50 in East Hampton at least, and millions across the country."
History is replete with treehouses. European monasteries sprouted treehouses in the Middle Ages. In ancient Rome, Pliny the Elder records a banquet for 18 people in a tree.
In America, treehouses were big in the 18th century. And now, a treehouse revival appears to be growing by leaps and boughs.
The two-year-old World Treehouse Association, which has 250 members, held its second annual meeting Oct. 10-12 at the Out 'n' About Treehouse Resort in Takilma, Wash. Some 25 people paid $170 to meet experienced builders and practice new treehouse construction techniques.
As an "InTreePreneur" with his own treehouse design company, Peter Nelson has built 15 "full-scale" arboreal dwellings. Adult treehouses cost from $5,000 to $45,000 and are sized from 100 to 450 square feet.
Mrs. Stiles says treehouses for kids are on the rise among people who want more contact with their families and the outdoors - as well as a little distance from modern technology. The couple encourages families to build together, or even for youngsters to tackle the job.
"Children are looking for a place to get away from their parents, but not totally," Mr. Stiles observes. "In a treehouse, they can be masters of their own universe."
Among his building tips:
* Let the neighbors in on your plans. Show them a sketch and ask for suggestions. "Get the neighbors involved," Stiles recommends. "That way it doesn't come as a big surprise."
* Take a picture of the tree, then use tracing paper over the image to sketch what the structure might look like.
* Don't go too high. "Six feet in the air is good," Stiles says. Being low encourages more regular use and makes it easier to build.
* Posts, especially log-like ones, make good tree substitutes.
* Use lag screws 1/2-inch thick and make sure they penetrate 2 to 2-1/2 inches into the tree. Smaller screws can break when the tree moves. (Stiles's research indicates that screws and bolts don't harm the trees.)
* Build child-scale. You wouldn't want an adult-size door in a treehouse, nor does it make sense to put hand railings at adult height.
* Think twice before painting a treehouse, since even a green structure can stand out once the leaves have fallen.
* Be prepared to check periodically for structural soundness and splinters.
* Don't breath the sawdust or burn the scrap wood when working with chemically-impregnated, pressure-treated wood.
As far as the risks, the Stileses say that children are generally more careful when playing in a treehouse but the play style of young users needs to be considered in the design process.