"I'm never going to get anybody to agree with this kind of structure if they can't see it. I'll finish it knowing there's a risk they'll make it come down…It's kind of an outlaw's game; it's got that Huck Finn thing to do with it." - Peter Nelson
In my career, I have plant a lot of trees, from little conifers to specimen trees planted with a Vermeer. When I design with trees for a home, I think of trees as part of the microclimate, as habitat, as a familial symbol, an heirloom, a harvest or a gathering place. While we can specify trees for shade, visual buffer, fruit or visual accent, nothing personalizes a large tree more than building a treehouse within it. Recently I've seen articles and heard radio spots describing treehouses, fantastic elevated deck structures inspiring a childlike wonder. For me it’s a boy’s fascination borne of my grade school fort and the lost summer days of childhood.
But with our childlike fascination comes a very real adult responsibility. Like any activity that we design for children, ultimately we may bear a great liability as well. All landscape designers planning traditional decks face a host of restrictions and structural requirements. But if a designer is asked to create a treehouse, we often find a void in the code. Regulations and specifications are often explicit for a deck that stands at waist height, but the deck that is designed way up in that backyard tree may be left to the imagination. In fact, designers, contractors and municipal codes do little to address treehouse design, structural requirements and the necessary safety issues.
For example, in most municipalities, a landscape designer planning a deck is required to provide a handrail if planning more than three steps or an elevated area above 32” or so. Handrail pickets may need to be 4” on center to inhibit pass through of a child’s head and stringent sizing requirements are set for weight bearing capacity of structural timbers. That would be the requirement for the steps to your front porch, but not twenty feet up in your sycamore tree. Isn’t a treehouse an elevated deck that is typically used by children? Prudent thinking would make construction requirements actually more stringent.
Here in King County, the County Council revised regulations a number of years ago. Now building permits aren't needed for treehouses smaller than 200 square feet (or about 14 feet by 14 feet) "used for play and similar uses." Are designers less liable because of lacking code requirements? Tell it to the attorney client with three small children. Locally, an individual that has created quite a stir is Pete Nelson, sometimes called the "poster boy" of the treehouse movement. Author of, "Treehouses: The Art and Craft of Living Out on a Limb," a book that has sold 150,000 copies, Nelson’s firm, Treehouse Workshop, is the largest treehouse builder in the country, grossing as much as $1 million annually. According to some sources, Nelson’s company may be building many of these without benefit of permit. Is this a safe way to design and build? And how many of these elevated deck structures are being built annually?
Here in Seattle a few years ago, we had a nifty little treehouse in a large laurel above a pond in our old Queen Anne sideyard. In building the treehouse, a little sunlight hole was inadvertently left in roof. Years ago, my 10 year old son encouraged his 8 year old sister and her new found friend to climb through the hole, up over the roof…and further up the tree trunk. They got stuck and called for help. I clambered up the treehouse ladder, squeezed up through the hole and climbed up the tree - to find them both clinging to the trunk on a horizontal branch. It was easy enough to lift my daughter from the branch and get her back through the rooftop hole. But when I reached for her friend, he fell – I still have in my mind the vision looking down of the canopy closing over him as he plummeted twenty feet to the ground below. Though he emerged only stunned (thankfully we lived across the street from a pediatric emergency doctor!), but it made me stop and reconsider treehouse construction and my place as a designer.
In the end, I was just lucky at my home. But if you build a treehouse at yours, you may not be. Regardless of what the code requires, create and consider a treehouse as a deck high above ground...or a step with a 20 foot riser.
TREEHOUSE RESOURCES
treesolutions.net: Scott Baker, of Seattle-based Tree Solutions Inc. Services.
treehouses.com: Site with tips & guides to build.
treehouseguide.com: Site with tips & guides to build, articles and blog.
treehouseworkshop.com: Construction, how-to and educational resources.
treehouses.org: "Treehouses & Playhouses You Can Build,"
by David and Jeanie Stiles (Gibbs Smith, $19.95).
KNOW THE BUILDING CODE (from Seattle P-I reporter Cecelia Goodnow). Seattle's building code treats treehouses as play equipment, so permits generally aren't required. But exceptionally large ones could spark land-use issues, so check with the Seattle Department of Planning and Development (seattle.gov/dpd) if you plan to exceed 120 square feet. King County generally doesn't require permits for family-fun treehouses of 200 square feet or less. But you'll need a permit if you intend to live in your treehouse or use it for commercial ventures. (metrokc.gov/permits)
(Treehouse image by Barbara Butler. See her beautiful stuff at https://www.barbarabutler.com)
