Yeah. Keep screwing. Assuming the base is level, I don't think you'd have any issues. Five sheets of Durock with whatever tile you use should get you to R= 2. Just a thought.
Next Gen is .39, so 5 layers and tile is just a teeny bit less than 2. My hearth doesn't get extremely warm even when running pretty hard. 1.97 is pretty darn close. 1/4" tile only adds .02.
I have a question on cement boards, I see durarock, hardiebaard, and wonderboard. The hardieboard appears to be denser; I saw some in Lowe's. It is only a few dollars more than the durarock. Wondering if anyone had anything to say about which is the best to use.
What you want is the highest r-value stuff you can get, so unless you plan to get some Micore, Durock is your best bet. I used Wonderboard, but it doesn't have as high an r-value as Durock.
I am going to use micore because it is all I can find. The durerock/wonderboard/hardieboard is used for the surface to support the weight of the stove and for the surface material which will probably be the cheapest tile I can find at Lowe's.
Those cheap slate tiles are about $1.50 at Home Depot here. That's what we used. There are big variations in color and thickness though, so you'd have to pick through them.
Of those three durock has the highest r value. I wold recommend using that since it never hurts to have more r value. As far as support I've worked with both durock and Hardie backer and I would say they are about the same.
Menard's charges $44.40 to ship the micore even though it is only around eight pounds. The sheets are not that large and I don't think it costs them anywhere near that amount to ship. However, I have searched high and low and that is the only source unless I want to pay more. M0st of the places list it as out of stock.
The surface material is not as important to me as getting the needed R value and stacking six boards of durarock does not appeal to me.
With Micore, 2 layers of Durock, tile/thinset, you're close to 2". With 6 layers of Durock, plus tile/thinset...a little over 3.25".
I can attest that it will be stable, if that's your concern. "Glueing" the layers together with mortar will give you pretty much a monolithic block of masonry.
I can also attest that it will be stable. I couldn't move mine unless I used a sledgehammer. Mine is 5 layers and each layer is screwed to the previous one. No mortar/thinset, except under the tiles. Solid, solid, solid.
Plus the added weight of the boards. I am not sure what floor joists were used but I can be sure it is minimum code.
The stove is close to 300, the hearth will be 150, maybe. The load is spread out somewhat....not a point load. Unless 2x2s were used as floor joists, I doubt that's an issue, and I doubt ANY code is that lenient.
Anyone done business with Kamco? They are closed today but open at 7 am Monday and so will give them a call. If that is a bust then it is Menards.
That is actually the cheapest I have found that actually had it in stock. The fireplace places wanted $55 for a single sheet 20"X72".
Am I making things too simple and redneck? My hillbilly tech degree is making me wonder why you couldn't get 1x4 and frame out the needed size and mix a batch of cement in a wheelbarrow and simply pour a hearth on the floor for $50 of sac-crete and some water?
