Sunday, March 29, 2009

Uncle John's Tree House

While we were up at the cottage on March Break, John decided to repair the tree platform he had built for his children about ten years ago. It was a great time to get together for a beer, do something fun and useful, and let Rudi play with his cousin Natalie for a while. The platform was robustly built off of two white spruces, with a step ladder up, railings around, and a slide off the side. Although it was very well built, It was not designed with a foundation system that would accommodate the growth of the trees, and of course these two little trees packed on quite a bit of girth over the course of their lives. His goal was to rebuild the foundation in a manner that would accommodate all future growth of the trees without causing any futher damage to either the platform, or the trees.

The original foundation was incorporated into the floor joist framework, and consisted of a rectangular box built around the two trees. Over the years, the trunks grew outward into the box, and eventually pulled the box apart. The new foundation consists of two 2x8 beams that are lag bolted into the trunks, one at the front and one at the back of the trees. The joist framework that supports the floor deck now simply rests on these beams, and the beams are free to slide under the joists as the trees grow. The first and second pictures show the right hand tree, along with one of the old floor joists, as well as the two new main beams underneath. Notice on the trunk the depression left by one of the (now removed) 2x6 joists making up a portion of the foundation. The third picture shows both main trunks, as well as the front main beam, two existing floor joists on each side of a new 2x6 floor joist we installed.