How thick should the subfloor be? and can OSB be used or does it have to be plywood? I'm thinking of using foam sheathing for the walls...anyone have experience with this? I couldn't find small enough windowns, so I bought shutters that open and close, and the shutters move up and down to let in light or shut. Do you think thats enough for CT winters? I know you need ventilation anyway. And is 5x5 big enough for about 10-11 chickens?