Research Pt 2: Huh, Huh, I got wood.

I guess the most basic place to start researching is the lumber.  It goes without saying that the majority of the lumber that we need to use should be rot resistant.  Of all the choices like Cedar, Hardwoods and composites,  pressure treated lumber is by far the cheapest and there gets my attention.  At first I was hesitant  to use treated lumber because I remembered all the stories about how treated lumber was actually treated with arsenic to keep away the injects and I sure as heck did not want to have the tree house that my kids play in be pre-poisoned.   Come to find out they have not been using arsenic since 2002, so we are good to go.

For the most part, there are not many drawbacks to pressure treated lumber, but there are a few points that need to be addressed:

1) Pressure treated wood is still not a great think to breath, so wear a mask when cutting and DO NOT burn it.

2) Treated lumber is treated with Chromated Copper Arsenate (CCA), and that
means we can have corrosion issues.  More specifically, any metal in contact with the wood can become corroded quickly due to galvanic corrosion because of the Copper.  It will not do any good to have wood that didn't rot when all the nails, screws and bolts holding it all together falls apart.  So with that in mind, everything needs to be galvanized.  Everything.  No exceptions.  We will go in more detail when we discuss the hardware.

So we are going to use treated lumber.  As for sizing, this is what I figure we will use, although this is open to change once we get further into this:

2x10s will be used for the beams that are attached to the tree.  The beams are holding the whole thing up, so they need to be stout.

2x8s or 2x6s will be used for the box frame.  The box frame is the floor joists and header boards.  I guess the size we use will be determined how much the joists are going to be cantilevered over the beams ... so we will have to figure out what is the safest later.  I may use 2x6's for the roof joists too ... but I need to figure out if they need to be treated or not.

2x4s for sure will be used for any walls that are built.  Again, they may not need to be treated, but for sure the bottom sill boards on the walls will be treated.

4x4s will be used in the corners of the structurs to pin everything together and will be used to make the posts for railings.

1x6s will be the decking for the platform.  This for sure needs to be treated.

As I stated before, I want to keep this cheap.  I am looking for used lumber that people don't want, so Craigslist will be the best bet.  I actually already found a guy that wants to sell some, so cross your fingers that I can get some good stuff ...cheap.