Redhawk said:
Pyper, what went into the construction of your hearth? also, what brand of stove do you have?
redhawk
It's a Dutchwest non-catalytic "medium"
(broken link removed to http://www.vermontcastings.com/dutchwest_noncat.asp)
For the hearth:
First, we needed to add additional joists, because the original floor is on 24" centers and the flooring wasn't very strong. Since it's over a crawl space, this was just a matter of cutting the wood and putting it in place. Then we put a beam in to cut the span from 7' to 3.5'. This part was probably overkill, but I had the beam and the blocks, so it didn't cost anything but 20 minutes of time.
Inside the room we framed the area with 2x4's ripped in half. So about 1.75" tall. We put the framing on top of each of the joists, and then screwed 3/4" plywod onto the framing.
The mason did the stone work. The Vermont Castings (Dutchwest) owners manual specifies an R-value for the hearth. I don't remember what it is, but I calculated that two layers of 1/2" durock plus the stone would easily get there. One layer might be enough, but might not, depending on the stone. I also made sure it would be large enough.
The mason cut the durock with a concrete saw and screwed it down. He covered the plywood with roofing felt. The front edge got metal lath, but I don't think there's lath on the flat surface. He put down more than an inch of mud, and sank the rocks down into it. He also used wooden spacers to keep the rock off the sub floor so I'd be able to get the flooring under the rocks, which worked out great. He used the concrete saw to cut the verticle pieces of rock. He spent roughly a half a day working on it -- it took all day, but a lot of the time he was out working on something else waiting on the moartar to dry.
If I could go back in time I think I'd frame it with full 2x4's to make it a little higher. It's not bad as it is, but if it was a bit higher I think it would be more comfortable when loading and cleaning. I also would have put insulation in the space under the rock. As it is I plan on insulating the floor instead. There's some insulation now (R-4 rigid), but more would be better. Rolls of R30 are $10 right now, so I got one to put under it.