As an example, if the stove is 24" wide, then you will need at least 48" of plate, so 12" on either side of the stove is protected besides the 24" behind the stove. Same for the height.:: Dusty when I lived in virginia the building code there said 36 inches to combustible material. When I installed a wood stove in my house this spring it said 36 inches to combustible materials also. That seems to be a common number. If you have a 24inch stove I think you should use a piece that is 72 inchest total behind the stove with the stove centered in it. That would give you 36 inches to any combustible material.
I just put a new Heathstone soapstone wood stove in and I love it. The directions for it said to use a double wall pipe from the stove to the ceiling and that allows me to have the stove pipe 8 inches from combustible material. I am not sure why a building code would not let you use double wall pipe it is safer and a whole lot more expensive.
My wife tries every new type of cleaner that the TV can point out to her. She got some stuff called DAWN power blaster (made by the same people that make dawn dishwashing soap) You can spray it on a woodstove window that is covered with residue. Let it set for about 5 minutes and then wipe it off. I have never seen anything clean those windows like this does.