I realize that this is probally a newbie question, if I am using 2x8's for walls, can I go over 12' on the sidewalls(ie 14'-16') and be safe? 2x8 lumber is actually cheaper here and I would like the extra insulation. Thanks for the help.
John
w* John,
2x8's would be good and will good insulation warm or cool depending on season.
By building 14 or 16 ft tall walls am I correct to interpret this to mean you would have an upper floor and then the roof above that? Yes, this is very doable. Sixteen feet would virtually be a two story. Either would permit rafters to rest on the upper plates of the walls. If 14 footers were used the upper floor headroom might seem a little short. You could raise the rafter ties above the top plates a little to improve headroom in the upper area. (Rafter ties can move up but are limited to being in the lower third of the rafter triangle, no higher and not lower. Same could be done with 16's but may not be necessary. Note rafter sizes (depths) need to be increased when moving the rafter ties very much.
For something like this a sturdy, stable foundation will be necessary.