You can always specify the type of warehouse it is. If it's for wood, then "lumber warehouse" or even "lumber yard." If it's for grain and animal feed, then "feed warehouse" or even "feed barn." It really depends on what it is being used for which is why you're getting many terms for it. As it sits empty and could still be used for a variety of things, you could describe it as "a versatile warehouse perfect for any of your large storage needs."