The foundation has to be level. I constructed mine over patio squares laid on a sand base because of easment considerations. The installation manual is a real turn off because of its size however EVERYTHING has its own illustrations and is to a certain degree redundant. As I followed the instructions I found that I was moving through the pages pretty quickly. Four hands make the process go much faster that just two. I did most of the errection myself but had to have help when it came to the last roof panels. For a thousand plus dollars I could have constructed a conventional building of my own but it would never have been completed in 12 hours. For what it is (feels like a doll house) it has allowed me to move all of the lawn &amp; garden stuff out of the garage which was the goal. I know that I will be moving again with in the next two years and when I do I will probably take it with me. It is a well thought out, precision product.