Been quite a few years of water running down the side of my chimney shell. (Not going to call anything wood a chimney). One side, looks like the sheathing is all mushy and the cedar siding has had it. So, once I tear all this out and do it over, do I backprime the cedar like I intend to? Tyvek? Also, what idiot would build a house without gutters? I already know the idiot who bought it....me.