Rear Heat Shield

I have a question.....
I am in the process of constructing a hearth pad for our Jotul Castine. The gentleman who is doing the installation requested
that I make the pad big enough to account for 12" of clearance from the wall to the rear of the stove. He made this request so that he would have room to accomadate the 90' elbow that will connect to a thimble/sleeve in the wall. Seems like a good idea....
So to make the hearth the correct size I need to know the depth dimension of the stove and I need to account for 16" in the front of the stove too. The Manual I downloaded from Jotul say's that this dimension is 23 1/4. Does anyone know if this dimension includes the "rear heat shield"? The manual really isn't claer about this. Unless I am missing it?? This is sort of important
because our house is small and I would like to make the hearth as small as I possibley can, without sacrificing safety and code of course....!
Does anyone know if the rear heat shield adds to the depth dimension?????

Thanks! Thanks! Thankyou!

Thanks Ryan
So when you say "X amount of clearance" do you mean that with the heat shield I can set the stove 12 inches from the wall, then just attach the heat shield and still maintain clearance? Which is 7 inches with a heat shield.

Doc

Sorry one more question.....

Does the heat shield add 2 or 3 inches to the depth of the stove???

Thanks

Thanks Again!