Hi Well I just want to be able to walk about in the taller part down the middle! I dont want to floor right to each corner as its a bit pointless. I did not consider the walls being able to breathe I was just thinking of boarding it up all the way round to make a rectangle, I am also going to insulate the roof and put up a plaster board cieling, I never intended it to go this far I just wanted a floor at first. Can I use mdf for my walls? if I build brackets behind it with 2x2 All my floor is down and Im quite happy with how straight it is, lol I guess all the hard work was done for me as the main beams are quite straight!