Newbie needs to build hearth extension

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Jellybean

New Member
Feb 17, 2008
3
Albany, NY
Hi,

Bear with me; I have no idea what I'm talking about. But I'll try to be as descriptive as possible. I've just moved into a new home with a fireplace. A wood-burning insert was removed, and I'm using the fireplace just fine. But the hearth extension, such as it is, is not to code. (Needless to say, I've got a heavy screen and am very careful.)

Here's what I've got: The firebox is 34.5"W x 30"H and sits 16.5" off the floor. The fireplace itself is 89" wide. The existing "hearth extension" runs the full 89" length, but sticks out only 4" from the fireplace opening. It is a 2.5" thick piece of bluestone. The entire fireplace is covered with mortar and bluestone.

I'd like to have a hearth extension that extends out enough, ideally, to meet code, but at least provides some protection from stuff flying out of the firebox and onto the floor. A nice place to sit would be an added bonus. I've been told by my chimney inspector that a proper extension, to code, would run me about $4,500 and require lots of construction (cutting out the floor, framing something underneath in the basement, pouring concrete, etc.). But I've been reading a bit online and am wondering about framing out a box upstairs (so as not to get the basement involved or necessitate pouring concrete) that is covered in some non-combustible material, and then mortar and bluestone. I've been hearing a lot about something called Micore and something else called Hearty Backer, and getting the impression that I could use these between any combustible materials (like wood) and the mortar/bluestone. But the terms are pretty Greek to me, so I'm not sure about what I'm reading.

Can anyone shed some light on this, in layman's (or women's) terms, that might help me find a less expensive and intrusive, but adequate solution? Or, if anyone's got any other ideas, feel free. I'd also been envisioning a hefty piece of slate or something, installed just above the existing 4" bluestone slab, and supported by some diagonal corbel kind of thing from underneath. Possible?

Thanks,
Lori
 
your on the right track,4500 is way high for what you are looking to do " I think" you don't need to get all in the basement deal. thats excactly what I did, I frame it out, it's only 2" off the floor, and then I have a large piece of blue stone exstended out to meet code. the whole thing is only 4" above original floor. looks very nice. I have a Hearthstone homstead siiting on it. My stone was around $200, a piece of plywood, some mortar, a couple of 2x4 s and some time. total was around $400, I also had some little trim pieces of blue stone , increaseing the cost a little. long storie short....if it's not to late....your on the right track, even better if you can do it yourself!
 
I appreciate you responding. I'm a bit confused, though. Is it plywood right under your bluestone? I was told there needs to be something between the plywood and stone hearth so that the wood doesn't get too hot. That's why I was looking into Micore or, and I just found this yesterday on this forum, Durock?

Anyone else have any opinions?
 
Is this just a regular masonry fireplace or a ZC type fireplace? If so you only need a non combustable surface no R factor required so no Micor or Durok (cement board )needed
 
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