A stove needs a pad...otherwise you may end up with serious problems. Our wood stove needs a 42" x 48" minimum pad with an r-value of 2. Well IF you could find one, I do not think we could afford it! Ouch, so we decided to, obviously, diy it. It was really interesting trying to find directions on how to actually build one. There were a couple ways to go about it, a lot depending on what R value you needed.
The one that worked best for us required micore, believe me that stuff is interesting! It's light weight yet dense and makes a nice powdery mess when you cut it. We got ours at Efireplace Store, it was reasonably priced and got here in less than a week...with free shipping! Most of the other supplies we got at our local Menards.
It required layering the micore, some aluminum flashing, and cement board. All of that combined gave us over our required r-value. Forgive me as I forgot to take pictures of this part. Our area was 42" x48" and the layers like this; our old floor, micore, aluminum flashing (so heat would spread out), another layer of micore, and then cement board. We used 1/2" Durock Cement Board from Menards, we could have used the 1/4" but we were worried about tile cracking.
After he got his new "toy" set up, we got to work putting down tile.