Single piece of Bluestone tread as hearth extension pad?

[Slagathor]

Hello! I did a bit of searching, and couldn't find anything that quite answers my specific question. Hoping for a little bit of help, if possible.


I have a Pacific Energy Neo 1.6 insert. Unfortunately, as you see in the pictures, a smart Aleck previous owner removed the heath extension entirely, and put laminate floor right up to the fireplace. Sine I got it the insert installed, I've just been using a generic hearth pad that the install company sold me. It's falling apart and I'm looking for something nicer and more permanent.

My plan is to drop a single, solid piece of bluestone in front of the stove. I'm just looking for the best way to install it. As you see in the second picture, once I pull up the laminate I'll have ~1.5" of clearance. Bluestone tread is 2", but I should still be able to swing it. When I drilled a hole through the floor, it looks like there is about an inch of "stuff" before getting to the crawlspace. It's either: A. An old hardwood floor on 1/2" plywood subfloor, B. just a really thick plywood subfloor, or C. Knowing my house, some crazy nonsense no one in their right mind would ever think of. Either way, I'll likely strip it down to the studs, this way I can add a little extra framing under where I'll put the stone, just to be safe.

Here's where I need some help. My plan is to put down 1/2" plywood on the framing, and then the stone on top of that. Should I use mortar in-between? Thinset? What kind, specifically? I'm just not sure. I see a lot of people put tar paper and lath, but this is when they are either tiling or placing multiple stones. This seems unnecessary for one giant, 150 lb+ stone. With that weight, do I even need mortar? (I'll at least put some between the new stone hearth extension and the existing hearth so embers can't get to the subfloor).

It just seems odd to me to put down tarpaper or some underlayment, and then glue/mortar this stone to the paper, not to the subfloor. Plus, as you can see, I don't have a whole lot of wiggle room between the framing and the bottom lip of the stove.

Sorry for the text block, just trying to give as much info as possible. Any help would be greatly appreciated!!

 

[DAKSY]

What I would do, BEFORE you lay your hearth, however you decide to do it,
Is to install a "Hearth Strip" (or strips) made from metal the are under both the
unit AND the hearth & extending 3 - 4" under each.
If there is a height difference between the floor under the unit & the floor under the bluestone,
you will need a bending brake to make the strip correctly. It will keep embers from getting to the underlying material...
Figure 7.8 below shows an example...

 

[Slagathor]

What I would do, BEFORE you lay your hearth, however you decide to di=o it,
Is to install a "Hearth Strip" (or strips) made from metal the are under both the
unit AND the hearth & extending 3 - 4" under each.
If there is a height difference between the floor under the unit & the floor under the bluestone,
you will need a bending brake to make the strip correctly. It will keep embers from getting to the nderlying material...
Figure 7.8 below shows an example...View attachment 264780

Thanks for the advice! Would not have thought about that. Just figured that if the flimsy little hearth pad worked for 5 years without a fire, a big slab of bluestone wouldn’t have an issue. But I didn’t keep in mind that the hearth pad has a layer of metal on the top.

Also, that manual is very handy! A lot more detail about hearth specs then my Neo 1.6 manual had. Thanks again.

 

[bholler]

Hello! I did a bit of searching, and couldn't find anything that quite answers my specific question. Hoping for a little bit of help, if possible.
View attachment 264768View attachment 264769

I have a Pacific Energy Neo 1.6 insert. Unfortunately, as you see in the pictures, a smart Aleck previous owner removed the heath extension entirely, and put laminate floor right up to the fireplace. Sine I got it the insert installed, I've just been using a generic hearth pad that the install company sold me. It's falling apart and I'm looking for something nicer and more permanent.

My plan is to drop a single, solid piece of bluestone in front of the stove. I'm just looking for the best way to install it. As you see in the second picture, once I pull up the laminate I'll have ~1.5" of clearance. Bluestone tread is 2", but I should still be able to swing it. When I drilled a hole through the floor, it looks like there is about an inch of "stuff" before getting to the crawlspace. It's either: A. An old hardwood floor on 1/2" plywood subfloor, B. just a really thick plywood subfloor, or C. Knowing my house, some crazy nonsense no one in their right mind would ever think of. Either way, I'll likely strip it down to the studs, this way I can add a little extra framing under where I'll put the stone, just to be safe.

Here's where I need some help. My plan is to put down 1/2" plywood on the framing, and then the stone on top of that. Should I use mortar in-between? Thinset? What kind, specifically? I'm just not sure. I see a lot of people put tar paper and lath, but this is when they are either tiling or placing multiple stones. This seems unnecessary for one giant, 150 lb+ stone. With that weight, do I even need mortar? (I'll at least put some between the new stone hearth extension and the existing hearth so embers can't get to the subfloor).

It just seems odd to me to put down tarpaper or some underlayment, and then glue/mortar this stone to the paper, not to the subfloor. Plus, as you can see, I don't have a whole lot of wiggle room between the framing and the bottom lip of the stove.

Sorry for the text block, just trying to give as much info as possible. Any help would be greatly appreciated!!

Does the insert state a required r value for the hearth extension?

 

[Slagathor]

Does the insert state a required r value for the hearth extension?

No, it does not say anything about an R-Value in the manual. Just this:
“Ember protection: Combustible floor in front of the fireplace insert must be protected from hot embers by non-combustible material extend- ing 16” (USA) and 18” (CANADA) to the firing side and 8” to other sides of the unit.
Consult CAN/CSA-B365 Installation Code for Solid-Fuel-Burning appliances and equipment in Canada, and N.F.P.A. 211 Standard for chimneys, fireplaces, vents and Solid-Fuel-Burning appliances in USA.”

 

[bholler]

No, it does not say anything about an R-Value in the manual. Just this:
“Ember protection: Combustible floor in front of the fireplace insert must be protected from hot embers by non-combustible material extend- ing 16” (USA) and 18” (CANADA) to the firing side and 8” to other sides of the unit.
Consult CAN/CSA-B365 Installation Code for Solid-Fuel-Burning appliances and equipment in Canada, and N.F.P.A. 211 Standard for chimneys, fireplaces, vents and Solid-Fuel-Burning appliances in USA.”

Ok just checking. In that case with the metal strip you should be fine

 

[Slagathor]

What I would do, BEFORE you lay your hearth, however you decide to di=o it,
Is to install a "Hearth Strip" (or strips) made from metal the are under both the
unit AND the hearth & extending 3 - 4" under each.
If there is a height difference between the floor under the unit & the floor under the bluestone,
you will need a bending brake to make the strip correctly. It will keep embers from getting to the nderlying material...
Figure 7.8 below shows an example...View attachment 264780

What is this HX3 and HX4 the manual refers to? A bunch of manuals and online forums mention it, but I can’t actually find the product itself anywhere.

 

[DAKSY]

From the table on the page below, it appears to be similar to Micore 300.
The R & K values are the same. It may just be a Hearth & Home Technologies designation

 

[woodwarm]

Hi i am in new jersey also. i have a center fireplace in my home..i knocked out back and installed two way wood stove..now because i knocked out back i had to establish a new hearth to match the other side. when i removed the old stone hearth on original side i found quite a depth of concrete underneath. my plan like was to put a singe piece on bluestone on each side to use as hearth. but researching i found out that by fire code you need a certain r value for the hearth. the piece of bluestone on the new side would not be enough r value to satisfy code. i did not want to pour cement on new side. so i researched and found the cardboard like product that i could lay down that with bluestone would satisfy the r value needed and save me from pouring concrete. I got the sheets from kb fireplace in ramsey. i do not recall the name of the cardboard like sheet but you can call kb I'm sure..this saved my a lot of time and effort and no problems now with code etc..i hope this helps..

 

[Slagathor]

Hi i am in new jersey also. i have a center fireplace in my home..i knocked out back and installed two way wood stove..now because i knocked out back i had to establish a new hearth to match the other side. when i removed the old stone hearth on original side i found quite a depth of concrete underneath. my plan like was to put a singe piece on bluestone on each side to use as hearth. but researching i found out that by fire code you need a certain r value for the hearth. the piece of bluestone on the new side would not be enough r value to satisfy code. i did not want to pour cement on new side. so i researched and found the cardboard like product that i could lay down that with bluestone would satisfy the r value needed and save me from pouring concrete. I got the sheets from kb fireplace in ramsey. i do not recall the name of the cardboard like sheet but you can call kb I'm sure..this saved my a lot of time and effort and no problems now with code etc..i hope this helps..

Hm, interesting. Thank you for the recommendation. I'm guessing it's something like Micore 300 board. I'll give them a call!

The R-value thing confuses me a bit, because my stove manual doesn't seem to say anything about an R-value. I'm starting to think that it doesn't have an R-Value requirement, and says to follow the general fireplace codes, which just says you need at least 2 inches of non-combustible material for the hearth extension.

Also, this flimsy little thing passed inspection:
Amazon product ASIN B00LNGIFZ2
I guess it's possible it still has a higher R value than 2 inches of bluestone...

 

[woodwarm]

It could be the micore 3000 kb fireplaces would know. I have a slabs of bluestone on each side not sure thickness but probably what ever is standard. I read natl fire code and learned that the bluestone alone would not satisfy hence the micore 3000 or equiv. When inspector came i tried to exclaim what i did but he could have cared less honestly. But i know what i did was correct for my own peace of mind. My stove is double sided but also double depth so it puts out a lot of heat and i can pack with 16 pieces of wood easily. Good luck