My 'chook shed' with the roll off roof. Been up for over 10 years now and surprisingly no problems. The pine fence palings are rubbish and warp terribly so there's a few gaps for the wind to get in. Rabbits have dug a little home underneath, there's been the odd rat and a couple of bats too so it sure aint vermin proof. I put some small alloy channel running the length of each side and each half of the roof sits on four plastic wheels with steel bearing inserts and it only requires a couple of fingers to open and close. Built on complete ignorance and very little carpentry skills but it works nicely for me. Pier is just four pine boards joined together, concreted in and filled with sand - pretty solid although there's some vibration if you kick it