Tips for building a natural stone hearth

[zdinkins]

Hello all,

Apologies if this is the wrong forum for this thread (I'm new here).

I am building a new stone hearth for our wood stove and am looking for tips. Surprisingly, there are few helpful youtube videos that I could find. I am aiming to pick up some local East Tennessee flag stone for the hearth floor. For the half wall behind it, I'll break up the flag stone into smaller pieces (about 12" or less). I've got some ~4" tall thicker curb pieces that will be the base 'kick boards'.

I've never done this before so I'm hoping to get some tips and tricks from the pros. I'm a pretty handy person, and have done plenty of tiling in the house so figure it isn't too far off of that.

All stone will be backed by cement board...1/4inch for floor and 1/2inch for walls.

Any specific grout and mortar tips or materials?

Here are some examples of the look that I am trying to achieve. Much appreciated!

 

[EatenByLimestone]

The starting point is to figure out what size it needs to be and what R value you need. Since you know the material you want to use, you can then figure out how thick it needs to be for that r value.

 

[zdinkins]

The starting point is to figure out what size it needs to be and what R value you need. Since you know the material you want to use, you can then figure out how thick it needs to be for that r value

 

[zdinkins]

The wall is already framed with insulation. Not tracking how r values come into play?

 

[zdinkins]

The wall is already framed with insulation. Not tracking how r values come into play?

 

[EatenByLimestone]

Ok. So your wall insulation has nothing to do with this. Your stove puts off heat. This radiates out and without protection for the wall and floor, can set them on fire. You need to find out how much protection your wall and floor needs so you don’t set your house on fire.

 

[zdinkins]

Oh r value from the stove. Gotcha. This cabin has been here for 46 years and the was literally nothing but dry wall on the back and some crappy tile beneath. Never had any issue. In the 10 years that we’ve had I’ve been very aware of it and it’s never seemed like it’s putting out enough heat to be a problem.

I’m re-building it with backer board, thick mortar, and thick natural stone. The insulation from the heat will be way better by default.

 

[EatenByLimestone]

This type of damage doesn’t happen quick. Don’t fool yourself. Do it right.

 

[EatenByLimestone]

@bholler

Do you have a pics of walls you opened up?

 

[zdinkins]

@bholler

Do you have a pics of walls you opened up?

 

[EatenByLimestone]

He’s a chimney sweep. I’m sure he’s opened a few walls that have always been fine… until they weren’t.

 

[bholler]

@bholler

Do you have a pics of walls you opened up?

I will look but I dont think I do on my phone

 

[bholler]

This is one that caught fire after about 60 years of use we had to rebuild

 

[stoveliker]

The point is this: long (decades of) exposure to too much heat can lower the auto-ignition temperature of wood. I.e. you're all good for half a century, and suddenly you have a fire in the wall.

So read the manual of your stove, and look at the clearances. Those are the distances from teh stove *to the first combustible piece* (In your case the paper on the drywall). It doesn't matter if there's noncombustible (stone) in front of it.

 

[zdinkins]

Okay cool. Thanks for the solid insight on it. I’ll dive into that to make sure it’s installed safely. Any tips on the grout/mortar and stone work? Or YouTube channels that teach some tips? Had some surprising difficulty on the YouTube academy for natural stone hearth building.

 

[begreen]

Is this for the CDW stove? What model is it? That will determine the hearth and stove clearance requirements.

 

[stoveliker]

I don't know enough about grout or mortar for natural stone.
I redid the tile on cement board behind my stove, and used polymer modified, cement-based non-sanded grout, and polymer-modified thinset mortar.
These were standard thickness 3"x10" tiles though, not heavier stone.

 

[EatenByLimestone]

Is there a tag on the back of the stove?