Saturday 21 April 2007

Can you Build the Perfect Tree House?

April 22, 2007

Many a child has experienced the joy of gathering bits of cast off wood to create a lofty palace.

I remember many hours of hunting and gathering to make the perfect tree fort. In retrospect my lack of carpentry skills probably saved many a tree from an untimely death. Trees are long lived dynamic organisms that sway in the wind and grow over time expanding there girth and height. Houses are long standing static decaying structures that are built not to move and require constant input to keep them from falling apart. How can the two exist in a Tree- House?

Often times the answer is, not very well.

If the house is attached firmly to the trunk and wrapped around the branches completely two things will happen. First the house will start to break up like a ship on the rocks as the tree moves to and fro in the wind. Secondly the boards that are used to attach the tree to the house will slowly strangle the tree and eventually cause it to die off above the attachment point. Surprisingly one thing that won’t happen is the tree will not lift the house higher into the air as the tree grows. Trees don’t grow like Jacks bean stock. Trees grow incrementally adding layers of cells to the outside, like dipping a candle in wax or applying layers of paint. Trees gradually get thicker and larger. Only the growing tips of the branches will elongate and get taller or spread wider.

Now back to my lack of carpentry skills. Typically as a ten year olds we would gather

two by fours and old bent nails to attach a frame work in a few places to the tree. A piece of weathered plywood would be flopped on top of the makeshift floor joists. The whole thing was not very safe, not very sturdy, yet it was relatively harmless to the tree. A few strong winds and the whole thing would collapse or have to be reattached to the tree. These rarely survived the winter.

If you consider that half of the people that fall accidentally from 6 ft or higher do not survive the fall, it’s lucky my cohorts and I are alive. Some tree house makers may have grown up into crack liability lawyers.

Do all arborists wax poetic about there childhood tree adventures, or is it just me? The other day I was out to a property where a client had hired a professional carpenter to build a state of the art tree house in a multi stem willow. They had built it structurally to code.

Was there anything we could do to stop the tree from ripping the stoutly built structure apart? How long would the tree last with this house attached to it? The prognosis was not good; the tree had already started to swell over the 2 by 12’s that completely surrounded the stems of the tree and the roof was not in good condition either. With the tree house in place, the tree had 3 to 5 years before it started to die back and fall apart. The house was also supported by 4 by 4 poles that had either bent or lifted depending on how the house had shifted.

If you’re thinking of a tree house consider suspending it from large limbs with cables, like an extremely large bird feeder. You could also build a house on stilts next to a large tree. Position the house so it doesn’t rub on the tree and the tree doesn’t strike the house on stilts. If you’re determined to build your tree house, contact an arborist and a creative carpenter and you may come up with the perfect compromise.

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