Focus on good design and clever construction In Myakka River State Park in Florida, a walkway suspended 25 feet above the ground and stretching 85 feet through the forest canopy leads to a 74-foot tower (see photos, below) with a panoramic view.
Canopy Construction Associates, a nonprofit based in Amherst, Mass., built the structure in 2000 with the help of park staff and volunteers. They precut all the pieces in 3 1/2 days in the park's maintenance shop; after that, "it was like a big raising," recalls Robbie Oates of CCA.
To transport lumber upward as they framed the tower, the builders used a Chance CapStan hoist anchored to a tree, plus a couple of pulleys. They ran a rope from the hoist to a directional pulley attached to the tower's framing on ground level. For the first four levels, the rope ran straight up the center of the tower to a pulley rigged on a tree limb — but when the tower reached the same height, the branch had to be removed.
To frame the upper levels of the tower, the builders needed another way to hoist the heavy posts up. Alan Frye, a timber framer who designed the tower, thought up a clever solution: a job-site rig that looked like a sawhorse, only bigger — 6 feet high and 15 feet long — and slightly tipped. Notches on top of the sawhorse's two "A-frames" seated double 15-foot-long 2x6s; the bottoms of the A-frames sat in the corners of the level just built (see drawing, below).
The builders attached the upper pulley to the 4x6 beam at the top of the sawhorse, and then, in Oates' words, "We hoisted the corner post up the middle of the tower to the level we were standing on, disconnected the top grab point (for guiding), brought the primary attach point (on about the middle of the post) to the top of the saw horse, then plopped the post into the corner. When we were done framing that level, we moved the rig up to the next level, using walkboards.
"It's a system we can easily transport to the jungle," Oates adds. "We used the same idea later, when we did a job in Peru, for a 100-foot-high tower." — Laurie Elden