I have a friend who is going to make me my own little chicken house with attached run. This is going to be for a silky hen and any chicks we put in there. So in the figuring I need to have this tall enough so that a heat lamp can go on top. This coop will be outside and I live in the midwest where winters can be nasty so i have to think about this. How tall should i make it?? For width I figured 2 foot for roosting area and 12 inches for nesting box area.