When he was a boy, Enoch Elwell built a three-storey treehouse in his New Jersey backyard, using scrap wood, and without the assistance of a DIY-minded dad. He and his friends played in it regularly, he says: "It was a death trap, but somehow we all survived."
Now 28, Mr Elwell is attempting to recapture his childhood with a Kickstarter campaign to raise more than $30,000 (£19,000) for construction of the Treehouse Project, a cluster of eight to 10 holiday treehouses in a valley on the outskirts of Chattanooga, Tennessee. "Treehouses remind you of the possibilities and enjoyment of being young," says the entrepreneur. "It's the experience of getting away and having an adventure."
Mr Elwell's business partner, Andrew Alms, who is 27, says treehouses are a booming sector of the "glamping" market, because they offer the experience of the great outdoors, but with indoor loos. More and more treehouses are being built in the United States, not only for children but also as home offices, guest houses and tree-house resorts.
"We think we're on the front of a huge trend," Mr Alms says.
Mr Alms, whose background is in land development, and Mr Elwell plan to ensure their treehouses are environmentally net-positive, boasting all mod cons, but producing more water and electricity than they consume.
They have identified the stand of trees that will hold up their first treehouse, to be built with reclaimed wood from a 19th-century barn. If they meet their fundraising target before the mid-December deadline, they intend to welcome their first guests to the Treehouse Project in March 2015.
Over in Oregon, Michael Garnier, 66, the owner of the Out'n'About Treehouse Treesort, estimates that demand for parts from his mail-order treehouse supply business has doubled since 2013. "I've been selling parts for years but in the past year it's really exploded," he says.
The Out'n'About Treesort comprises 15 treehouses – said to be the highest concentration of treehouses in the world – with some as high as six storeys above the ground, so housekeeping staff have to get their cleaning kit to the rooms using ropes and pulleys. Many of the treehouses are connected by elevated walkways.
Mr Garnier built his first treehouse in 1990, but two years later was told by the local authorities that he must close it to guests, because it did not satisfy safety standards.
So, he invented the "Garnier limb", a specialised anchor bolt that supports the weight of a treehouse without damaging the tree over time. Combined with sliding brackets that allow trees to move and grow without ripping the treehouses apart, the technology has allowed Mr Garnier and other treehouse builders to create structures that last not just for years, but for decades.
The treehouse boom has its origins in the Pacific Northwest, home to the biggest trees in the US, where Mr Garnier and his fellow treehouse-builder Peter Nelson organised the first World Treehouse Conference in 1997. Last year, Mr Nelson, the author of several books about treehouse building, launched a Grand Designs-style television show on the subject, Treehouse Masters.
Mr Garnier, who is about to star in a similar series, The Treehouse Guys, points to Mr Nelson's small-screen exposure as the reason for the recent growth in the treehouse market.
Mr Nelson, 52, told The New York Times last year: "I get calls all the time [to build] kids' treehouses. But I think the adults who are placing the calls are hiding the fact that the treehouse is for them."Reuse content