Fill stone gaps with what?

I am getting a Jotul Oslo installed in a couple weeks. I am in the process of making a hearth pad. I have some 1.5 inch thick flagstone that I am setting in Flexbond thinset. My question is: What should I use to fill the gaps between the stones? They are irregular shapes, so some of the gaps will be up to 1.5 inches. I'm assuming this kind of gap is too large for normal sanded grout. Can I use the Flexbond thinset? The grey color is fine.

I guess so, or just some regular old type S mortar.

Does the stove require more than just an ember barrier?


Matt

It only needs ember protection, but the flagstone would look nice.

Looking back i could have tinted the cement? But way too late for that

http://www.concretenetwork.com/chris_sullivan/colored_concrete.htm



Just a thought don

loon

Correct, the Jotul Oslo does not require any 'r' value for the pad, just ember protection. The type 's' mortar sounds like a good idea. Thanks for the help.