We have used 8' sheets for some of our home made arks, and found that the max height you can have the entrance door in the centre (4 foot, less the wood strip going across at the top connecting the two sides of the front wall) is only just tall enough for a large sow to get in and out. Also once inside they can only walk in the centre part of the ark, though it doesn't seem to bother them that much. When you buy arks kits like this, consisting of the 8' sheets and the curved plywood front and back wall, the doorway is always tiny and only suitable for youngish weaners. If I was to build another, I would try to build the long side walls about 12 to 24 inches higher than the floor level with the corrugated sheets sitting on that, so that the curved bit would easily accomodate large pigs over a much larger floor area than when the semi-circle is placed at floor level. If any of that makes sense, don't think I explained myself very well!