Make a World-Class Tree House: One Dad's Step-By-Step How-To
A chain hoist helped raise a heavy pile of green oak, barn siding and pine flooring up into this formerly unoccupied Kentucky coffee tree. (All Images Credit: Lajos Geenan)
By Logan Ward
It’s a common-sense rule of treehouse construction: Make it lightweight. So I felt some stirrings of anxiety when the stocky, bearded sawmill owner pulled up to the house with a flatbed trailer stacked with oak timbers. Full of water, densely grained and smelling like bourbon, the rough-cut framing lumber I’d ordered spanned 18 feet and looked like bridge supports. As we offloaded the first 2 x 8, each of us taking an end in hand, I smiled doggedly to mask the strain I felt. He peered over the garden fence past the lilac bushes, and politely asked, “What kind of treehouse are you building?”
One thing was certain: It wouldn’t look much like the rickety aeries of my childhood, hammered together out of whatever construction scraps and packing crates we neighborhood kids could scrounge up. (The most ambitious of these was a three-story fort spanning a creek and topped by a crow’s-nest made from an old kitchen chair nailed to the trunk.) This time, I’d enjoy the advantages of milled lumber and a carpenter’s square and level, not to mention power tools. Yet I hoped to match the spirit of those earlier tree forts with a rustic structure where my children could waste their afternoons dreaming up rules to games I’d never understand or even hear about.
As kids, my friends and I never bothered with plans. We had an abundance of trees and were eager to start hammering. Today, there are exactly four mature trees in our backyard. I consider them all irreplaceable—at least in my lifetime—so after deciding to build a treehouse, I thought long and hard about where to put it. The ideal host was a 70-foot-tall Kentucky coffee tree standing alone in a corner of our small lot. It rises 15 feet before its trunk sprouts into a balanced, oval-shaped crown that filters sunlight through its leaves like flour through a sifter.
As an adult and a conscientious neighbor, I also thought hard about what the treehouse would look like. I wanted something that would not seem out of place in the historic Virginia downtown where we live. No cheap-looking plywood box or precious playhouse on stilts would do. The structure would be modest in size, and the materials would have an outsize effect on how it looked. I asked my friend John Foster, a capable craftsman who built the log cabin where he lives, for advice.
“I’d use green oak,” John said, gazing up at the tree. The timbers would be strong and rot-resistant, and they’d age beautifully, he explained. As proof, he pointed me to the bed of his pickup truck, which held a 4 x 6–inch oak beam that he uses for skidding landscaping boulders. “See that old timber? That’s been bouncing around back there since I built my house,” he said. Fresh from the sawmill 20 years ago, the green oak had grown silvery gray with a rough, raised grain—a handsome piece of wood, I had to agree. It didn’t occur to me to ask how much green oak weighs.
The scrap-wood citadels of my childhood (above, left) lacked a certain sophistication that comes with actual planning. After struggling to draw my new design on graph paper, I built a model out of cardboard (above), specifying details like a Dutch door, lap siding and an observation deck on one side.
Building a treehouse is a lot like any other construction project, with one main difference: Instead of a foundation, a treehouse rests on a platform. The platform should be sturdy enough so that whatever sits atop it—gingerbread Victorian, open-sided play hut or, in my case, rustic cabin—doesn’t attach to the trunk. That minimizes damage to the tree and keeps the swaying on a windy day from prying apart the structure. It also, frankly, is a mark of craftsmanship—the difference between banging together boards as a kid and doing it right, with a measure of adult skill and judgment.
If you’re building high off the ground across several trees, even your platform needs to allow for tree movement. You can either install an expensive system of treehouse cables and bolts or rig your own free-floating beam. If the tree is mature and sturdy and your platform rests in the bottom eighth of the tree, you can use a fixed platform. I modified a classic design, sketching plans for an 8-foot-square platform that would surround my tree at a height of 7 feet.
That was plenty high for my son, Luther, and daughter, Eliot, ages 10 and 7, respectively. During the planning phase, I let them climb a ladder to the mark on the trunk where the floor would go. When I held up the 3D cardboard model I had made, their eyes lit up. But to be honest, I had no idea how they would respond once it was built. Society has changed since the freewheeling 1970s, when my boyhood friends and I roamed the neighborhood, scavenging construction sites for scrap lumber and nails like cul-de-sac Robinson Crusoes. Would my kids take to the treehouse, or would they prefer to stay inside playing video games and snapping together Legos?
Seven feet may not sound very high, but working overhead made bolting my platform beams to the tree a major challenge. My anxiety over handling all that heavy lumber eased a bit after I cut the beams down to 8-foot lengths with my circular saw. Still, each one weighed probably 100 pounds. What saved me was a chain hoist, a gadget most often used by shade-tree mechanics to lift engine blocks out of cars. I borrowed one from John, who uses it to lift stone for his landscaping jobs. The mechanical advantage of the gear differentials made raising my beams as easy as tugging on the chain with two fingers. And the ratcheted brake prevented the load from slipping backward. The hoist did the work of two men, never faltering and never once complaining.
That was fortunate, since I mostly worked alone. This was too big a job for Luther and Eliot. They helped in small ways—handing me tools, picking up dropped nails with a magnetic sweeper—but they preferred to stay on the ground, hammering scrap wood into sailboats and slingshots. It was refreshing to know that their prepackaged, adult-designed games were sitting untouched inside.
To minimize my impact on the tree, I anchored each of my four crossbeams with a single ¾-inch lag screw. To those beams, I attached rim joists and floor joists. Using green oak meant that I had to predrill everything. Otherwise, I would never have been able to drive my nails home in that dense wood. Or I’d have split the grain trying. Even the biggest deck screws I could find seemed too thin and brittle for such formidable lumber, so instead I bought a couple of 5-pound boxes of zinc-dipped 20d nails. The going was slow, but I soon found my rhythm with drill and hammer.
Once my platform frame was complete, I began installing 2 x 6–inch tongue-and-groove yellow-pine floorboards. I knelt on loose boards, tapping each plank into place with a rubber mallet and then nailing it home. Soon I had enough floor in place to form a stable perch. I worked around the tree, leaving a 2- to 3-inch gap between it and the floor to allow for growth. I top-nailed the floor using square-headed cut nails. It was easier than nailing through the tongues. Plus, the old-fashioned technique added character—a touch that pleased me, though it would probably be lost on the kids.
When constructing the roof, I flashed the gap between the cedar shakes and the tree using a truck tire’s inner tube, secured with a bungee cord (above, left). A rustic ladder made of ¾-inch nylon rope and 1 ¾-inch dowels provides access—or, when hoisted up, thwarts invaders from terra firma (above, right).
At some point between my tree-climbing childhood and late adolescence, I briefly developed a fear of heights.
During a clandestine ascent of a water tower during my senior year in high school, I froze 10 rungs up, palms clammy, ground spinning below. Three weeks later, I followed friends up the same ladder, forcing myself not to look down. But then, after a few more climbs, once to the top of the domed reservoir (kids, don’t try this at home), my fear seemed to evaporate in the warm midnight air—I had simply been out of practice.
When I began building my kids’ treehouse, I felt out of practice again. Though my extension ladder hardly compared to the water tower, scaling it one-handed while lugging the chain hoist or a 2 x 4 made my knees wobbly. I eventually grew comfortable. Still, I decided to adhere to another basic rule of treehouse construction: Build on the ground. You’re faster and more efficient in close proximity to your tools, lumber and sawhorses. And face it, no matter how fearless you are working perched at precarious heights, the fewer trips up and down a ladder, the safer you’ll be. Real treehouse pros (and today, there are more of these than ever) trim out entire wall sections, including framing, siding, molding and glass windows, before hoisting them up to the platform.
Not knowing exactly how my walls would meet up, I didn’t go that far. I did frame three of my four walls on the ground, then raised them with the chain hoist. Once everything was aligned, I nailed the plates to the floor. Connecting the rear butt wall between the pair of side walls made me momentarily curse my decision to use green oak. I was just able to fit my drill and 6-inch bit between the studs. Face-nailing the 20d nails was even more awkward.
The job got frustrating once I started working up high, building the fourth wall and roof rafters. Like some kind of Newtonian poltergeist, gravity spilled nails, tipped boards over the edge and tugged my power cord to the ground, forcing me down and up my ladder over and over. Back on the platform, I’d reach for my measuring tape or pencil and see it lying in the grass by my sawhorses. I now marched up the 45-degree ladder as if up a flight of stairs. Nevertheless, I learned to always stow my tools in my tool belt and to loop the extension cord around a limb.
Things got cramped up there. One by one, I nailed the rafters atop the stud walls while standing inside the 5 x 8–foot house, alongside the mature tree trunk. The more rafters I attached, the less space I had for swinging my big California framing hammer. I felt a bit like the storybook Alice after she had grown so large her arm poked out the cottage window. Since the shed roof sloped from 7 feet down to 5 feet, I kept bumping the 6-foot 3-inch high crown of my head on the oak rafters. Recoiling in pain, I’d scrape my back or arms on the scaly tree bark.
Once the framing was complete, I drove a borrowed pickup truck 30 minutes to Dayton, Va., a rural Shenandoah Valley community with a large Old Order Mennonite population. I passed men in straw hats pedaling bicycles and driving horse-drawn buggies on my way to Martin’s Native Lumber. The warehouse was surrounded by what felt like an acre of siding, sawn and stacked high overhead, open to the sky and surrounded by pastureland. Martin’s had just what I was looking for—milled white-pine barn siding with a rough-sawn face. Most of it had been sitting in the yard long enough to turn a soft gray. When I told them I needed something thin and light for a treehouse, they offered to plane the ¾-inch stock down to 9/16 of an inch for a couple of pennies more per foot, bringing the total price per lineal foot to 50 cents, one-third the cost of the fancier pine siding from my local lumberyard. I ordered the same rustic pine in a thicker profile to trim the windows, door and corners.
The lap siding went up quickly and smoothly. The same was true for the roof. I laid cedar shakes over skip sheathing—1 x 4–inch boards nailed 5 inches on center across the roof rafters to allow the cedar to breathe. Snapping chalk lines, I crabbed myself from one side of the roof to the other, tacking down the fragrant shakes. Having to custom cut each shingle to match the contour of the curves slowed my progress. But I didn’t mind. That one-of-a-kind look is part of a treehouse’s charm. As with the floor, I left a gap around the tree trunk to allow for growth, as well as movement in strong winds.
My daughter Eliot performed a supervisory role during the construction.
One afternoon in early August, as thunderheads boiled up over the valley, John and I drove to some wooded property belonging to his wife’s family. He had a chain saw and loppers. I brought along gloves and a curved pruning saw. We felled half a dozen young red maples, with trunks as big around as my forearm. I limbed and cut them just as warm, nickel-size raindrops began drumming the hood of his Ford F-150. Back at the house, I cut the poles down to 28 inches and nailed them between pairs of 2 x 3s to create railing sections. I fastened those between 4 x 4–inch oak corner posts for a rustic railing sturdy enough to withstand anything my kids could dish out.
By then, much to my delight, Luther and Eliot were raring to go—to climb, explore and inadvertently test the structural soundness of things the way only kids can do. I quickly fashioned a ladder out of wooden dowels and nylon rope. To keep the heavy hatch from slamming shut on young fingers, I strung a counterweight (an old railroad hammerhead I found at a junk shop) through a small pulley above. As the hatch slowly closes, the weight rises inside a section of PVC pipe. I built a Dutch door and installed it between house and porch. Not long after I had put my tools away, I found a scrawled note on the kitchen counter.
“Dere Dad,” it read, “I have gon awt to the tree haws, Eliot.” She and her friends Grace and Gillian were hauling blankets and books and snacks up by rope and bucket.
“I love this transportation!” Grace yelled as she hauled up another load. I smiled, realizing this was probably the first treehouse any of them had ever seen. A different era. Soon, they raised the ladder and battened down the hatch, and Luther fired holly berries at them from below with a homemade slingshot as shrieks echoed through the neighbors’ backyards.
During the kids’ first week back in school, a late-summer wind blustered up. I raced out back, wobbling up the rope ladder and through the hatch under the guise of conducting a wind-worthiness test. The oak framing felt solid underfoot, and I smiled, glad to have built with it, more glad the construction was done. I wedged myself in a corner and rode out the gusts. The sky was a crisp blue, and sunlight flashed through the windows as branches swished and whipped. As the timbers creaked, I felt both snug and exhilarated to be sailing in the wind. For a moment, I was untethered, free—like a kid in a treehouse.
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