Build the Ultimate Tree House

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Tree House Craft
Total Time weekend projects

For months, a small cloud has been floating over our nine-year-old's head. "Build me a tree house," it says. At times, Matthew voices his dream out loud. We'll be sitting in lawn chairs under our favorite shade tree when he eyeballs the branches. "I could go up there and read," he tells us. "I could lower snacks down to you."

Like ooze in a sci-fi flick, the notion envelops our eleven-year-old Jacob. "I've wanted a tree house since I was three," he says. "Mom, when I have my friends in the tree house, Matthew can't come up, right?" he continues, laying the groundwork for a juicy territorial dispute.

It seems we are going to build a tree house.

What you'll need

  • Goggles and dust masks
  • Plumb line
  • 2-foot level
  • Reversible drill
  • Jigsaw
  • Hammer
  • Handsaw
  • Combination square
  • Tape measure
  • #2 Phillips head screwdriver
  • Posthole digger
  • Steel wheelbarrow (for mixing concrete)
  • Shovel
  • Extension ladder
  • Two 40 lb. bags of concrete mix
  • Two 6" lag screws, 3" galvanized screws, three packs of 20 each (for roof, balusters)
  • Two pounds 3 1/2" galvanized nails, five pounds 2 1/2" spiral deck nails
  • Plastic tarp for roof
  • Two 4' x 4' x 16' (for posts)
  • Seven 2' x 6' x 8' (for frame, joists)
  • Fourteen 5/4' x 6' x 8' (for floor)
  • Four 2' x 8' x 8' (for railing)
  • Twenty-eight 2' x 2' x 8' (for balusters, roof)
  • Five 2' x 4' x 16' (for diagonal supports, ladder, rungs)

How to make it

  1. Right Location

    For expert advice, we have a carpenter friend (whose name, ironically, is Mr. House) help us choose a tree. The five of us stroll the grounds, looking for what Mr. House calls "the perfect crotch," limbs set just so to cradle a wooden floor.

    No, we don't want the tree house right over the garbage cans. And no, we didn't really want the boys dangling over our favorite deck chairs. And yes, that chestnut tree with the two limbs spreading like a victory sign might be the one. Never mind if you can't find the best boughs, says Mr. House. You can build between or around trees, over or under limbs. We choose the chestnut tree.

  2. The Corners and Frame

    First, we have to measure the rectangular frame for the tree house floor. If you get through this, you'll get through the rest. This is the hardest and most tedious part, and no one will enjoy it.

    We lay a 2' x 6' on the ground next to the trunk beneath the two limbs that spread into a V. The boughs rising through the floor will become, on one side, a natural railing and on the other, a living stool. We decide, in consultation with Mr. House, on a 5' x 6' rectangle. That leaves about 14' above ground--11' to the tree house floor plus 3' extra to become the corner posts for a railing.

  3. Four Corners

    Fasten a 2' x 6' to the tree with two 6" lag screws.

    Drop a plumb line from each end; mark where it falls with sticks.

    Using a square, measure the length of your floor from each stick and mark those spots.

    Use a posthole digger to dig two 2 1/2' deep holes. Pour 6 inches of concrete into each hole; let set 24 hours.

    Place 4' x 4' posts in holes; pack with dirt.

    For the frame, complete the rectangle by nailing the three 2' x 6' boards to the ends of the original 2' x 6', and to the outsides of the 4' x 4' posts.


    Try to rent a gas-powered posthole digger (instead of using a handheld one) to ready a hole for the cement.

    The fewer screws you use when building your treehouse, the less injury to the tree.



  4. Tree House Craft: Step 3

    Supports and Floor

    The next steps are a lot like connect-the-dots played with a level.

    Diagonal Support

    Cut wedges in the ends of the two 2' x 4's.

    Nail one end to the underside of the frame, the other to the bottom of the posts.

  5. Tree House Craft: Step 4

    The Floor

    Run 2' x 6' floor joists 16 inches apart and parallel to the original 2' x 6' board. Nail from outside the frame.

    Cut the floorboards to length and lay them perpendicular to the joists.

    Cut notches in the end planks to fit around the posts and all four rail supports.

    If desired, cut curves in the floorboards to allow tree limbs to come through.


    Leave some space between floorboards for rain, but not toes, to fall through.

    To ensure a sturdy tree house, you may have to shake the corners of the frame while building. It becomes a kind of tic: shake the frame, climb down the ladder, stare up, climb back, shake the frame.

  6. Tree House Craft: Step 5

    The Ladder

    Once the floor is nailed down, the ladder is ready to be assembled. When it's hammered on, take the time to barrel on up and admire the work in progress.

    Cut two 2' x 4's to match the height of the 4' x 4' posts. Space 16 inches apart.

    Place on bricks in the ground so the ladder won't sink, fit the top into notches you've made for it in floor, and nail it in. The top will poke through the floor and serve as railing supports.

    Attach 2' x 4' rungs all the way up, leaving 12 inches between the tops of each.



  7. The Railing

    You're almost done! Now for the finishing touches.

    Double up two 2' x 4's and run them through the notch you made in the final floorboard. The post should match the height of the 4' x 4' columns and ladder.

    Lay 2'x 8's over the four corner railing supports.

    Cut at a diagonal so each pair of sides meets to form a squared corner.

    Nail balusters 6 inches apart to the outside of the floor frame and screw each to the top railing.


  8. The Roof

    Attach vertical 2' x 2's to each corner. Join with four horizontal 2' x 2's to make a rectangular frame.

    Screw two other 2' x 2's at an angle to form a gable at each end and add a vertical support at the two center points.

    Join the gables by laying a 2' x 2' between them.

    Drape the frame with a tarp and staple down.

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