Heat resistant mortar
Okay, I just spent 2 hours getting absoultely nowhere on this one at HD and Lowes. I am building a hearth pad for my wood stove that is coming on Friday. According to the instructions I have, I am supposed to use 3/4 inch plywood with 1x3 or 2x4 supports or backers. That part's done. The next step is to secure wonderboard onto the plywood using "heat resistant mortar". After that is regular thinset, tiles and grout. The reason I have heat resisitant mortar in quotes is because every store I have gone into looking for it looks at me like I have two heads. So now I ask the garden web class, what is heat resistant mortar?
Please don't tell me to check with my town. Their response to all of my wood stove questions so far has been, "just follow the manufacturer specs". I called the company that makes the flexibond products and was told that they don't rate their products for heat. I looked at the cement products in the masonry section, but none of their products mention heat either. Does anyone know what I should be using for the wonderboard step and where I can find it?