If your planning on building a ladder stand, you should consider buying one first. If you plan on making it out of lumber, you are going to want to make sure it is pressure treated. With the price of lumber these days, it might not cost a whole lot more to buy one. You can get a 16'-0" ladder stand for around $80 at a lot of places. The advantage of buying one is

1) safer
2) last longer
3) lighter, easier to put up, down, or move

Just a thought.