It's made out of norway spruce cut into 400mm lengths and arranged between insitue pollarded Norway spruce uprights to make a corded structure. The window frames are made from pallets and the windows are milk bottles. Inside there is a log burning stove. The roof is 18mm thick OSB with visqueen on top then old carpet to protect the visqueen and then 100mm of turf. It's pleasingly cool in summer and freezing in winter - It's full of holes! Anyway it's a great place to crash after a night's drinking round the campfire. My son says it "comfortably" sleeps 8 but then teenagers aren't as fussy as the rest of us. Great fun to build; it took about 6 months at working weekends.