Have a lot of buildings built with these type of poles. How long are they? The ones we used ended up being short once dug into the ground. New posts might be a bit more true and easier to build off, some posts that were used had a 1/2ft difference between the top and bottom. Ours were used telephone posts that were removed when the phone lines were dug underground 50yrs ago. My sheds the posts are 10-12ft apart with a header so the rafters can be on 4ft centers. The sides are strapped with 2"x6" and then sided with tin or plywood. For a hay shed or cold storage its a cheap way to go. Our posts were free but used.