Figure out the size you need to store your stuff, then double it and it will still be too small! I put up a 30x40 about 8 years ago and it's way too small. I have to move stuff all the time. I have a small 10x16 heated work shop in the back corner. With a little work I can get four cars and the small stuff in for the winter but can't do anything then. My thoughts are build so you can easily add on in the future if need be.
