R Value??

[Mountian Man]

I am looking at the Regency i2400. I see that in the Manual that it states the hearth must have an r-Value of .893. It is going into an existing masonry hearth/chimney (With liner of course). The Hearth is raised two inches above the floor. It is natural stone with brick underneath. How do a determine what the R-Value of the natural stone is??

 

[stoveguy2esw]

hard to say not knowing what type of stone it is, i know that marble has an R value of 0.09 for a 1 inch thickness, common brick has a 0.20R value for 1 inch thickness. ceramic tile is 0.08R per 1 inch. i would have to make the assumption that most any "natural" stone is going to be about 0.08 to 0.09 per inch

hope this helps ya

 

[Mountian Man]

My fire box in the masonary unit goes all the way to the ground and has a footer poured. I know that will have the R-Value needed. My concern is with the hearth extension do es that also have to have an R-Value of .893?

 

[DougA]

http://www.marble-institute.com/stoneprofessionals/rvalue.cfm

If you have a 2" air gap. then stone, then brick you are more than fine IMHO.

 

[stoveguy2esw]

My fire box in the masonary unit goes all the way to the ground and has a footer poured. I know that will have the R-Value needed. My concern is with the hearth extension do es that also have to have an R-Value of .893?

typically the "floor protection" is the same R requirement for the entire protected area

 

[Mountian Man]

Can someone enlighten me please about the 2" air gap?

 

[stoveguy2esw]

non ventilated air gap beneath the hearth adds R rating as well, a ventilated air gap is R1.43per inch a non ventilated (closed off) air gap is R0.97 per inch

 

[begreen]

Is the hearth raised above the floor or is it just that the total hearth thickness is 2"? Not sure. Normal brick is already 2" thick, plus the stone should make it thicker than 2". Or is this stove going in a full masonry fireplace with a hearth step in front? A picture would help here.

 

[Mountian Man]

Yes the insert is going into a full masonry fireplace. The hearth extends out from the firebox 17" I am not at home right now but our fireplace is very much like this one minus the stove in it. It is all natural stone laid on top of brick the hearth is not flush with the floor it is about 2' above the subfloor height

 

[begreen]

It could be ok, especially if the hearth front is supported by the concrete footer. Is there a basement underneath where that can be checked? Some times they pour a cement hearth support that slopes toward the hearth footer. A picture will help us discuss it without so much guesswork.

 

[Mountian Man]

Here is a picture of my hearth with the old craft still in it

 

[begreen]

Is there a basement where you can see what is under the hearth?

 

[srbellis]

https://www.hearth.com/econtent/index.php/articles/hearth_design

here is a post with R values. Horizontal dead space is .97 per inch. That is what I am relying on. I have metal studs (3.5inches) with 2 layers of Durock. That should be plenty. Somewhere around R value of 3.5 by the time I add tile.