TH: Building a Tree House (fwd)

Dear Fellow Community Foresters,
You can imagine my amusement when I saw the following post on the newsgroup,
bionet.plants - anyone care to add some tree-friendly engineering advice?

Reply To ScottW -
A couple things to keep in mind are that the wood is only fully alive at a
thin green layer under the bark called the cambium, which is constantly
expanding outward in larger and larger diameters.  Avoid crushing this
tissue.  The *WORST* thing to do is to `girdle' the tree with any kind of
non-degradable material like a metal hose-clamp (ouch!) or even some plastic
twine.  A plastic ribbon can kill a tree over time by strangulation.  Most
often large wood-screws are used to secure to trees, parallel to the ground
(no, I don't know exactly why).  Generally they don't drill holes and insert
an all-thread type of uniform bolt thread, probably because of the small
gaps that are left along the bolt.  If you want to fill-in any gaps I don't
know what you would use.  Silicone solvents and the like are probably toxic
to the tree.  And there are conflicting schools over pruners' wax (creosote?),
but I like grafters' wax because it smells nice.  If you can leave several
inches for the tree to expand, and minimize the surface area impacted by
the rigging, your trees will be grateful.  (Hint: a large screw-eye fixed
to a galvanized cable will eventually get `eaten' by the tree, probably OK.)

	Richard < owner-tree-house@lists.umbc.edu > (Don't quote me on this!)

---------- Forwarded message ------------------------------------------------
Date: 29 JUN 1995 09:56:56 -0500 
From: Scott Williams <scottw@oscar.snsnet.net>
Newgroups: rec.gardens, triangle.gardens, bionet.plants
Subject: Building a Tree House 

I plan to build a tree house for my three children in the back of my lot. 
The area is wooded with pine, oak, hickory, and sweetgum trees.  There is a
clump of oak and hickory, six trees growing close together, that would seem
to be ideal for a tree house.   
I am concerned about not doing anything that would kill the trees.  Does
anyone know the best and safest way to fasten supporting beams and joist to
trees.  I am considering lag bolts or possibly suspending it from cables
looped through branches overhead. 
Any ideas? 
Scott Williams