How can I place one of these? I'd rather like to have one in my nice new house but I cannot figure out the placement rules. I checked here: http://www.uoguide.com/Stone_Oven But I'm not sure what qualifies as a "roof" or how to get around it. Any tips? Can I place it on lower floors or just on the top one? I tried every floor except the 4th/roof (which is a garden, so yeah). Help!