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Tuesday, August 8, 2000
I mentioned the treehouse project a few days ago to an acquaintance, and she asked, "How old are your kids?"
Kids? What kids? This is my treehouse! It started accidentally, as I was bro wsing through the do-it-yourself
home improvement books at Barnes & Noble a month or so ago, and there it was, a book on building TREEHOUSES! Lured in by the beautiful photography, I was soon dreaming of my own treehouse, swaying in the
wind between tree limbs. I became acutely aware that although we live in a log house on the St. Louis River in northern Minnesota, we didn't have a place to sit and relax , watching the river flow b y. Poetic images came to mind... I was transported. I wondered how I
had lived so many years treehouseless. I left the bookstore with my first treehouse book,
"Tree Houses You Can Actually Build" by David and Jeanie Stiles. So far the treehouse had only cost me $15.95.
I read most of the book in the car on the way home from Duluth. (Jerry is a pretty good driver, and only occasionally do I need to do any back-seat driving.)
The following day was sunny and cool, a great day to scout a treehouse site. I already had in mind a stand of trees on the other side of the beaver dam, along
the St. Louis River. I found the site I had in mind--two clusters of maple trees on the bank, either of which would mak e a suitable treehouse site. I chose the more scenic cluster to the south, with a better view of the bend in the river. The trees had to be at least 8 inches in diameter,
and some were larger than that. The space between the trees widens at higher elevations, but I did not want to build too high off the ground. Both
Stiles and Nelson point out that you can get a lofty sense of being airborne even five feet off the ground. I chose to build at eight feet of elevation as a compromise between the issues of elevation and the need for building
space between the trees.
Next I drew an artist's conception of my finished treehouse--I took several photos of the trees at different  angles, then using tracing paper, copied the trees, and drew in a picture of what I imagined the treehouse will look like--a sort of airborne gazebo, with
a deck, roof, a cedar railing all around, stairs and railing.
In the next week or so I had found two more books on treehouses, both by
Peter Nelson. Reading and rereading my books, I studied the first problem in treehouse design. The foundatio n must be flexible, allowing the trees to sway with the wind while still providing a wide safety margin for support.
The design for the foundation depends on the trees involved-since I was planning a treehouse nestled between four or more trees, I needed a system which would attach the foundation supports between the trees and
in some way fasten to the trees securely.
Since the trees are living, and the hope is to keep them alive, one can't simply bolt and hammer into the tree indiscriminately. Further problems
develop because the tree will grow. A hole drilled at 8 feet off the ground will remain at 8 feet. The tree grows taller from the top, but it will of course also continue to expand in girth.
 I borrowed a bracket design from one of Peter Nelson's photos, and found
a machinist who was willing to custom build four brackets for me out of 1/4 inch steel plate. These brackets are bolted to the four support trees with 1/2 inch lag bolts, eight inches long, only one for each bracket,
which minimizes the damage to the tree, and also allows the bracket to pivot when the tree sways. The 2 x 6 foundation  beams sit in the support brackets but can move when the trees sway in the wind. This is a completely floating system, with no fixed points of attachment.
The next expedition was back to the tree, armed with string, a measuring tape and a level, a hammer and nails. Jerry marked a level 8 foot on our four support trees, and attached
the string from a small nail in each tree. This gave us the measurement for drilling pilot holes with a 3/8 inch drill in each tree.
My dad loaned me a sturdy ladder, a block and tackle, a portable power drill and a
come-along. Next, I bought two 12 foot long 2 x 6  lengths of treated lumber, lag
bolts, and an assortment of drill bits. Then from LL Bean's on-line catalog, I ordered a 11 x 11 foot gazebo tent, with canvas on top and mosquito
netting on the sides to serve as a base camp. It will allow retreat away from the bugs.
Ground troops (Jerry and I) then carried the 2 x 6 lumber to the site, along
with brackets and tools. The dogs were also pressed into service. Muktuk, one of our 80 pound Alaskan Malamutes, was persuaded to carry
a pack, and brought a tarp and rope to the site. Candle, another of our Malamutes, is 12 years old and officially retired. She came along for companionship.
At the site, I followed Peter Nelson's advice to do as much as possible on the ground. We slid the 2 x 6's
into the brackets on the ground (they fit rather snugly so this involved a certain amount of hammering.) Then
we attached the brackets, complete with the 2 x 6, to the trees, Jerry, on the ladder, screwing the lag bolt through the bracket and into the pre-drilled hole while I held the other end of the 2 x 6 as high as I could from the ground. This was not as simple as it sounds as we were working in 80
degree heat, with mosquitoes and deerfly buzzing us the whole time, requiring long-sleeved shirts, gloves, and mosquito netting. The heat and
humidity and sweat fogged our glasses, further complicating the task.
Ea ch foundation board was attached by brackets between two trees about 8 feet apart. Once the first bracket was secure, the second was much easier to bolt.
We repeated the process on the other side of the trees, securing a second foundation board parallel to the first.
After this was accomplished, Jerry retired for a much-needed shower, and
I retreated to the gazebo tent. Haiko, another of the Malamutes, and I sat inside the tent and watched the sunset, listening to a family of beaver on
the other side of the river in their beaver house. I could hear squeals and murmurs and suckling sounds from the beaver kits as they nursed,
followed by the sounds of adult beavers chomping and munching on their own dinner. Splashing noises followed. Could they be washing dishes after dinner?
Wednesday, August 9, 2000
I picked up the new generator today. It weighs about 100 pounds, but at
least the box has handles. Tonight I swept  out the shed and Jerry carried it
inside for the moment. We didn't have time to do much more than eat dinner and feed the
dogs.
Now I'm studying the question of how to attach the floor joists to the foundation beams. At lunch time I drove over to Precision Welding and I showed a prototype
to Herb Hill, who made the foundation brackets. He saw me coming and called out, "we make no guarantees!" I reassured him that the brackets were working
fine, and I judged them to be likely the last thing standing in case of hurricane force winds.
He studied my new design which would have required about a dozen welds, and
was underwhelmed. He thought maybe I should go over to True Value & see what the ready-made
joist-hangers looked like "before I break the bank" with more custom-welding.
A sympathetic woman at True Value listened to my story and showed me their metal plate joist-hangers and
various and sundry brackets and attachments. Then she called for help from one of the guys. "She is making," she explained, "what sounds like a r ather elaborate treehouse...." All agreed that I had picked out the most likely joist-hanger design from
amongst the choices, and I left with eight of them on a trial basis, and of course a bag of nails.
Jerry and I discussed the problem tonight, and after considering
different possible custom designs, decided to try the ready made joists first. The question is, whether the floor joists can safely be attached to the foundation beams, or whether they
should be attached in a way that would allow the beams a certain amount of movement independent of the joists to minimize stress to the structure. Tonight I designed a new
simplified bracket which would bolt to the joist, but float on the foundation beam, yet not go anywhere, because it would be attached with a carriage bolt underneath the foundation beam.
I don't think it's necessary, though, and too much movement might weaken the platform in time. (I think I just enjoy designing these brackets.!)
Friday, August 11, 2000
Today I dug a couple of steps out of the bank next to the beaver dam,
which will make it easier to get up and down that spot from now on. I also picked up 2 x 6's for the floor joists and treated lumber decking. I hope we can get the platform completed this weekend.
Saturday,
August 12, 2000
Hot and muggy, rained this morning, but we carried 2 x 6's and tools and hardware down the trail, over the  beaver dam and down the trail again to the treehouse site. We fastened the 2 x 6 joists to the foundation beams with joist hangers, using a carpenter's square to keep
everything square. The joists were spaced every 16 inch es, as trees permitted, and
we tried to leave at least a 2 to 3 inch gap away from tree trunks to allow for growth.
I have ordered stringers for 4 foot wide stairs--five down to a platform, which in my lastest design version will be 6 foot
square, then ten stairs down from there to the ground. This will make the treehouse a split level, and provide a viewing platform about 5 feet
off the ground. It was going to be 4 foot square, then I thought, what the heck, won't be much more work to make it 6 feet and it will be just that much more fun. We got
most of the floor joists up and fastened, then Jerry hit his thumb with a hammer, kinda split the tip of the thumb open, and for some reason wanted to take a break,
so we just ate dinner. I'm hoping we'll be able to finish the joists tonight, and start on the decking tomorrow.
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