Thats not a simple question to answer fella, different people will give you different answers and the equation starts to become very complicated and not one to be cocked up if your dealing with an amount of quality product. Basically if the material is to be used for external use then it should be stored at a temerature in accordance to the external temperature, seperated from other sections within the pile and a through draft ideally should be present, The ends should also be sealed with oils or paint. Wood used for internal use should be stored at a temerature akin to that at which it is to