Rebuilding a hearth for my Insert

[batmanavich]

As I was preparing for my insert installation, I noticed a few things, some seem like a problem. The hacks that put in the wood burning fireplace cut out a good portion of the already undersized 2 x 8 floor joists, and made concrete forms for the hearth with some 1 x material. The concrete is not level, and has a large crack opening at the top side.

My plans are to remove the concrete hearth, and to reframe my floor structure to create two beam joists on either side, and to create a beam that will accept the joists that will end before the hearth area.

The question is, how would you guys recommend building the hearth up. I have a 22"x70"x2-1/4" Limestone hearth being made right now. The plan is to have the limestone's bottom to be level with the finished floor (white oak flooring).

The Kuma Sequoia should be arriving soon, and I would like to get the house ready to handle that beast.

Thanks,
Matt

 

[begreen]

Unless I am missing something, the manual seems to have skipped the hearth insulation requirement completely. For peace of mind I would call Kuma or at a minimum put down a couple layers of 1/2" Durcok NexGen under the limestone.

 

[jkranes]

As this is at least in part a tile question, I would suggest posting your question to the forums at www.johnbridge.com. I have found the folks there to be very knowledgeable and helpful about all things related to tile and stone, especially proper construction of a substrate appropriate for your limestone installation.

 

[batmanavich]

Talked to Mark at Kuma Stoves. He told me that the insert only requires ember protection.

The main part of my question was to look for recommendations on how to create the structure for this application. I am not completely sure it is best to have any wood under the hearth at all.

One thought I had was to drill into the masonry wall, place rebar in the wall, and to thru-bolt some angle iron into the beam parallel to the wall to support a new concrete pad. Then create a galvanized pan to act as a form and heat shield for the hearth.

I thought someone may have been in my position before, and could point me in the right direction. Hopefully I am being descriptive enough to explain what I need to solve.

 

[jkranes]

Is this similar to what you have in mind? http://www.johnbridge.com/vbulletin/showthread.php?t=103767.

If you are talking about a concrete slab that is not continuously supported underneath but instead spans the distance between beams on either side, that is a structural engineering question and will depend on the width of the span and the thickness of the slab. Probably an easy question for a structural engineer or architect but I'd definitely get professional input on that.

 

[begreen]

The design will depend on whether you make it purpose built for this insert. Or to a higher level for some future option? Considering that they just require ember protection only and hopefully you will be using this insert for the next 20 yrs, I would just go with your original plan.