“A treehouse is like being on a tree. A tree net is like being in a tree.” — Andrew Castle
The concept of a tree net can be confusing to some. It’s neither a trampoline nor a hammock, though it has attributes of both. Lagunitas resident Andrew Castle has been building these nets across the West Coast for over a decade, but he and his team of peripatetic handyman friends have been trying to produce the feeling of being in a tree since they were children.
To the lucky few who grew up visiting their nets, the structures represented a piece of West Marin that could not be infiltrated by outsiders: Often hidden in the woods and suspended more than 100 feet in the air, the nets were difficult to access for those who didn’t “know someone.”
For Mr. Castle, building the nets, like other professions he’s taken up, synthesizes his life passions, and he is now working to make his nets accessible to all.
Growing up in Lagunitas, Mr. Castle’s education took place outdoors. “Go play and don’t come back until dark,” their parents would tell him and his brother. The Castle brothers and their group of groms surfed, rode bikes, climbed trees and explored new places to hang out. One of their friend’s mother had taken part in tree sits in Humboldt County redwoods alongside activist Julia Butterfly Hill.
“The movement didn’t fully register to me as a child, but its ethos was ingrained in how I was raised,” Mr. Castle said. “Before I knew why it was bad to cut trees down, I understood that it was good for people to stop them from being cut down.”
Mr. Castle recalls a time when a friend showed him how to tie a dreamcatcher. Weaving the willow loops helped inspire the patterns he would later create in his nets. Most of all, his years of climbing experience gave him a nuanced understanding of being in trees, and building nets was a task he could do while in the air.
There are various stories as to how the nets grew from something Mr. Castle and his friends enjoyed to something kids from central Marin coveted. In middle school, it was just him and his friends building deep in the woods. Then they moved on to a few high-profile locations. One friend would show another, who would show another, until the nets became local lore among adventurous young cragsmen looking for the best view in rural Marin.
“In the early days, it was all fun and games,” Mr. Castle said. “There was no plan of making it a job. It was just fun.”
After two years of studying at the College of Marin, Mr. Castle was accepted by University of California, Irvine to study at the Department of Viticulture and Enology.
Working at Marin Brewing Company at the time, Mr. Castles said he wanted to be a master brewer, but he recalled staring into the abyss that was the free application for federal student aid and $50,000 of debt. He felt lost and unsure what his next move should be. Then his father suggested he apply for jobs at national parks, where he could feed his passions for climbing and nature.
Yosemite was the first to accept him. He worked there for a winter in 2006 as a ski lift operator at Badger Pass. Later he worked at a mule stable in the subalpine Tuolumne Meadows, resupplying back-country hotels in the High Sierra.
During his six years in Yosemite Valley, Mr. Castle embraced the mountaineer lifestyle: slacklining, climbing to great heights, riding 50 miles roundtrip on a mule, then relaxing at parties. “There’s a certain level of camaraderie felt between a community of people who live 10,000 feet high in the mountains with no access to phones or cars,” Mr. Castle said.
When he returned to the Bay Area in 2009, he lived in Berkeley, working as a rigger for concerts and theatrical productions, a job that utilized his extensive lexicon of knots. That Thanksgiving, he and a childhood friend decided to build a net for old times’ sake.
Though the nets of his youth were mostly built in secret locations, Mr. Castle said he now strives for a level of professionalism whereby he might be contracted to build a net in a place like Golden Gate Park. He engineers his nets to be safe for children, a reflection of how his views have changed.
“In youth, everyone wants to have something no one else does,” he said. “It’s in our nature, and these nets act as an extension of that for some people, like a surfing spot. Hidden spots and activities are always cool.”
He weaves his nets from Type III parachute cord, the same grade used by the military. The cord has a rating of 550 pounds but, when strengthened by a network of knots, it becomes a much stronger surface. You can bounce on the nets like a trampoline, but also walk with ease. The nets are taut yet elastic and they’re deceivingly transparent.
Mr. Castle compares his style of weaving to the way mycelia create their network of thread-like, branching hyphae, or the way collagen binds to create fascia in the human body. This approach is also what makes each net unique. Standing under the net and looking up offers a fractal feast for the eyes: the layer of net below the spiral of trees and, beyond, the sky.
On the other hand, a net with uniform stitching creates a moiré or interference pattern that gives the illusion of a stable surface. Though you can peak through individual holes, the surface appears solid.
“There are other tree net makers out there but they’re making hella predictable patterns,” Mr. Castle said. “They’re not as taut and not as see-through because there’s a plane your eyes can rest on—it’s graduate-level science, really.”
Mr. Castle said the nets are difficult to appraise but they often end up coming out at $75 per square foot, making the setting for our interview somewhere around $15,000. Although the cost of materials for the 6,000 feet of paracord required for the net is expensive, the idea, Mr. Castle said, is that the net will likely outlive the trees. Our 12-by-12-foot surface was surrounded by 120-degree walls that connected to four towering Douglas firs. The steps that led to the net were constructed from the smaller trees that once stood in the net’s place.
Mr. Castle’s team consists of Fairfax resident Ben Bloom, a carpenter who travels across the country working on large treehouses for ambitious homeowners, and Santa Cruz resident Nick Williams, who grew up in San Anselmo and works closer than anyone with Mr. Castle. Mr. Williams has built many nets on his own and Mr. Castle regards him as a fixture of West Marin, citing his knowledge of the land, culture and history.
Mr. Castle said he hopes to continue turning his childhood hobby into a lucrative and inspiring business. “The nets speak for themselves,” he said. “There’s no need to convince anybody of anything once they step foot on them.”