Building hearth for WB insert

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jjbaer

New Member
Hearth Supporter
Oct 24, 2006
781
OH
My current masonry fireplace has a 16" x 60" hearth which is flush with the carpet and the cement in the fireplace that my current insert sits on. I've ordered a C450 Jotul which requires an 18" hearth as measured from the glass and the glass sits about 2.5" out from the front of the fireplace. This means I need about a 22" deep hearth and it needs to have an R factor of 2.9.

Since my current hearth is flush with the floor, I thought I'd build a new hearth measuring about 22" x 62" that I can simply place over the existing hearth. This way I can simply lay the new hearth over the existing hearth and won't have to tear up the old one or cut carpeting because the edges of the new hearth will simply rest on the carpeting.

My choices seem to be these: 1) since the stove and the hearth need to rest on the same level, I can build my hearth all the way from the back of the concrete insert floor area and extend it out 22 inches or, 2) I can build the hearth flush with the wall and out 22" and this means I need to elevate the back of the stove to be even with the hearth elevation, which is no problem. But if I do this, how do I then keep the EDGE of the wooden frame of the hearth which sits under the lip of the insert from being too close to high temperatures?

I've heard people say to use metal studs with insulation stuffed in-between the studs to achieve high R-values but at the studs themselves the only R-value you have is the Durrock or other material which sits on top of the studs and since I need an R of 2.9, how do I get R=2.9 AT each stud? That is, between the studs you have a high R value because you've placed insulation in between them but AT each stud you only have a metal beam so how does one achieve a given R-value AT each stud and what does code say about reduced R-value AT the studs?

Any suggestions?
 

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Another thought you might consider is trying to build a hearth that extends your current setup out further while staying flush with the existing hearth and carpet.

You probably have a carpet and pad for about 3/4" to an inch of thickness, then a layer of 3/4" particle board or plywood over a plank subfloor. If you cut out a strip of carpet and the subfloor under it, you probably could build back up with a layer of 1/2" Micore and a layer of 1/2" or 3/4"Durock covered with a thin tile, possibly with a layer of sheet metal in the middle. The result will (barely) meet the R-value requirements, and give you something flush with the floor, which you might find preferable. (I know that I'm not fond of the way a raised hearth eats up room real estate...) If you choose the right tile, and made it surround the existing hearth, you might even make it look like a deliberate design element rather than an addon to meet code.

Gooserider
 
Gooserider said:
Another thought you might consider is trying to build a hearth that extends your current setup out further while staying flush with the existing hearth and carpet.

You probably have a carpet and pad for about 3/4" to an inch of thickness, then a layer of 3/4" particle board or plywood over a plank subfloor. If you cut out a strip of carpet and the subfloor under it, you probably could build back up with a layer of 1/2" Micore and a layer of 1/2" or 3/4"Durock covered with a thin tile, possibly with a layer of sheet metal in the middle. The result will (barely) meet the R-value requirements, and give you something flush with the floor, which you might find preferable. (I know that I'm not fond of the way a raised hearth eats up room real estate...) If you choose the right tile, and made it surround the existing hearth, you might even make it look like a deliberate design element rather than an addon to meet code.

Gooserider

Gooserider,

I'm coming to that same conclusion and between you and Elk I may solve this yet. I'll send you photos to see what I mean.
 
I got your PM and responded to it, however if you don't mind sharing your photos with everyone, I really prefer to discuss this sort of thing in the thread. That way other people can see what is happening and possibly learn enough from it not to make us need to keep answering the same questions over and over...

My personal take is that PM's should be saved for things like personal contact info, or other things that you have a real reason not to want to share, or that wouldn't be of interest to anyone else (like details on a for sale item transaction)

Gooserider
 
When we had the new stove installed, we had the carpet cut out and tile put in front of the old hearth to give us clearance. Not only does it look nice, it is so much easier to clean up spilled ash with a small dustpan than dragging out the vac for the carpet.

Please share your pictures when you get a chance.
 
Ok...here's what the current hearth looks like. Edit: tried to attach it but it said can't exceed 1200 by 1200 pixels but the image is only 124K in size. How do you make it load this image?
 
Cast, I'm guessing that the resolution of the image is high. Reduce it to 72 dpi and it should be ok. If that's a hassle send it to me and I'll do it for you.
 
BeGreen said:
Cast, I'm guessing that the resolution of the image is high. Reduce it to 72 dpi and it should be ok. If that's a hassle send it to me and I'll do it for you.

I sent it...did you get it?
 
Nope, did you PM it? Snail mail? :)
 
BeGreen said:
Nope, did you PM it? Snail mail? :)

BeGreen......I sent one picture to your PM...did you get it?
 
BeGreen said:
Nope, did you PM it? Snail mail? :)

Ok. BeGreen was nice enough to shrink this for me so (hopefully) here's the photo of my hearth area. I currently have 16.5 in from the wall and the manual says I need 18" from the glass and the glass sticks out 2.5" so I need 20.5" (21" to be safe) from the wall..... an extension of about 4.5" from the 16.5" I currently have. Note: old Buck stove in photo and Jotul C450 due shortly.
 

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3 Micore 300 sheets 1/2" thick and 1 sheet 1/2" durock should give you R=3.46. What is the R on the hearth that is in place now. If it is high enough a hearth extension out front is enough. If not you could level the extension with micore and durock then cover existing hearth with durock and Micore to get the R value needed and tile the whole thing. That is what I did on this install.

HearthStone Heritage break in fire!!
https://www.hearth.com/econtent/index.php/forums/viewthread/3106/

The hearth is 2 inches high. Natural stone slate tile, really Quartzite on ½" Durock cement board all on ½" Micore 300 as a base for the hearth. "Combustible flooring must be protected with a covering of noncombustible material with an R-value of 1.2" is needed for the 2004 HearthStone Heritage hearth.


What is the top clerance to mantel for the new stove you may need a heat shield or need to move the mantel up.
 
DriftWood said:
3 Micore 300 sheets 1/2" thick and 1 sheet 1/2" durock should give you R=3.46. What is the R on the hearth that is in place now. If it is high enough a hearth extension out front is enough. If not you could level the extension with micore and durock then cover existing hearth with durock and Micore to get the R value needed and tile the whole thing. That is what I did on this install.

HearthStone Heritage break in fire!!
https://www.hearth.com/econtent/index.php/forums/viewthread/3106/

The hearth is 2 inches high. Natural stone slate tile, really Quartzite on ½" Durock cement board all on ½" Micore 300 as a base for the hearth. "Combustible flooring must be protected with a covering of noncombustible material with an R-value of 1.2" is needed for the 2004 HearthStone Heritage hearth.


What is the top clerance to mantel for the new stove you may need a heat shield or need to move the mantel up.

Elk suggested I look at the hearth from the crawlspace and he was correct that the existing 16.5" hearth is under concrete.....it's a wedge- shaped concrete extension coming from the cement chimney footer so it meets the code already for the first 16.5". I was thinking about doing something similar to that which Gooserider suggested....I could remove the 3/4" thick carpet/pad, then remove the 3/4" plywood floor and leave the sub-floor beneath that in-place. This would give me 1.5" to work with. Since Micore 160 has an R value of 2.86 per inch, I could use 1" Micore 160 (R=2.86), 1/4" Durorock (R= 0.125) and then 1/4" tile (R value of 0.02) for a total thickness of 1.5" and R value of 3.005 which meets the R value 2.9 requirement......Any ideas?

As for the mantle.....I have a heat shield ordered with the stove to meet top mantle height requirements so that's taken care of.
 
That sounds like a plan, good idea using the 160 Micore. I would do a small sample test with small cuts of micore, board, tile, cement, screws and all to check the total height first. I would go out further than the min. in front, more is better to stop sparks, glowing embers and the mess of wood burning ending up on the white carpet. Try letting the tile pattern size set the size of the extension. Buy tile, set pattern you want on the floor in front of the present hearth. get the pattern looking good. Then start tearing out the floor boards.

My hearth ended up 20" in front of the glass, just 14.5" was needed. I was just thinking next year I might just pull my stove into the room a little more closer to 18" to the edge.
 
castiron said:
Elk suggested I look at the hearth from the crawlspace and he was correct that the existing 16.5" hearth is under concrete.....it's a wedge- shaped concrete extension coming from the cement chimney footer so it meets the code already for the first 16.5". I was thinking about doing something similar to that which Gooserider suggested....I could remove the 3/4" thick carpet/pad, then remove the 3/4" plywood floor and leave the sub-floor beneath that in-place. This would give me 1.5" to work with. Since Micore 160 has an R value of 2.86 per inch, I could use 1" Micore 160 (R=2.86), 1/4" Durorock (R= 0.125) and then 1/4" tile (R value of 0.02) for a total thickness of 1.5" and R value of 3.005 which meets the R value 2.9 requirement......Any ideas?

As for the mantle.....I have a heat shield ordered with the stove to meet top mantle height requirements so that's taken care of.

Sounds like a good plan to me as well, and I would very much agree with DriftWood's suggestions about making the hearth extra deep and also doing some "test stacks" to make sure the thickness of the extension matches up right - don't forget to allow for the thickness of the tile adhesive! (I'm not sure how much to allow...)

Is that nice oriental design border part of the wall to wall, or is it a seperate carpet? If it's part of the wall to wall, I'd say your best bet would be to try for either flush with the edge, or possibly a very narrow white border, assuming that gives you the required clearance (hard to judge from the photo) Tile color isn't going to impact the fire numbers, but my guess is that it might be hard to get a match on that stone, plus the straight line where the two parts meet would scream that the extension was an add-on. I would suggest making the extension wrap around the three sides of the hearth, even though that isn't needed for code, and using a contrasting color, possibly trying to coordinate with the wood suround trim, or with some other room element. That way the extension will look like a "designer statement" rather than an afterthought...

Gooserider
 
Gooserider said:
castiron said:
Elk suggested I look at the hearth from the crawlspace and he was correct that the existing 16.5" hearth is under concrete.....it's a wedge- shaped concrete extension coming from the cement chimney footer so it meets the code already for the first 16.5". I was thinking about doing something similar to that which Gooserider suggested....I could remove the 3/4" thick carpet/pad, then remove the 3/4" plywood floor and leave the sub-floor beneath that in-place. This would give me 1.5" to work with. Since Micore 160 has an R value of 2.86 per inch, I could use 1" Micore 160 (R=2.86), 1/4" Durorock (R= 0.125) and then 1/4" tile (R value of 0.02) for a total thickness of 1.5" and R value of 3.005 which meets the R value 2.9 requirement......Any ideas?

As for the mantle.....I have a heat shield ordered with the stove to meet top mantle height requirements so that's taken care of.

Sounds like a good plan to me as well, and I would very much agree with DriftWood's suggestions about making the hearth extra deep and also doing some "test stacks" to make sure the thickness of the extension matches up right - don't forget to allow for the thickness of the tile adhesive! (I'm not sure how much to allow...)

Is that nice oriental design border part of the wall to wall, or is it a seperate carpet? If it's part of the wall to wall, I'd say your best bet would be to try for either flush with the edge, or possibly a very narrow white border, assuming that gives you the required clearance (hard to judge from the photo) Tile color isn't going to impact the fire numbers, but my guess is that it might be hard to get a match on that stone, plus the straight line where the two parts meet would scream that the extension was an add-on. I would suggest making the extension wrap around the three sides of the hearth, even though that isn't needed for code, and using a contrasting color, possibly trying to coordinate with the wood suround trim, or with some other room element. That way the extension will look like a "designer statement" rather than an afterthought...

Gooserider

Gooserider,

I agree and have already laid out what it might look like in Power Point and doing all three sides is the best. The oriental is a large rug and I can pull it a bit away from the front.
 
I laid out real tiles in front of the hearth and pasted over my Buck Stove insert with a photo of the Jotul 450 which I have on order to see what it looks like. Here's what it might look like:
 

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Not sure what the problem is, but the picture is the same size as the thumbnail, so I really can't see anything well enough to comment on it. However doing a mockup is a great idea.

Gooserider
 
I took the above photo 1-step further. I brought the photo into Power Point and pasted over my Buck Stove insert with a photo of the Jotul C450 that I ordered so that I could chose the correct color tiles. The photo now has the tiles laid out over the carpet and a photo of the stove. Any comments on color tiles? Hey the photo upload worked.....LOL
 

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Here might be a better image if it uploads.
 

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Ahh... Much better! That looks really nice, like it was designed that way for sure. The added tiles are an excellent color choice IMHO, as they pick up both the brown of the wood trim and the white marbling of the existing hearth stones.

Gooserider
 
Update......I picked-up my Jotul C450 insert at the dealers the other day ($2154 plus tax) and took it home. It's sitting in my living room awaiting delivery of my liner and my installing it. I bought 20 ft of 6" 316Ti ss, a stove connector, a tube of high-temp caulk, an insulation kit (25 ft of 1/2" thick insulation, adhesive, and wire mesh) and a one-piece combo wind screen/storm cap that screws onto my top tile and pivots open for cleaning, all for $700 delivered. Going to get a permit tomorrow and sheet metal to start the lower block-off plate.
 
castiron said:
Update......I picked-up my Jotul C450 insert at the dealers the other day ($2154 plus tax) and took it home. It's sitting in my living room awaiting delivery of my liner and my installing it. I bought 20 ft of 6" 316Ti ss, a stove connector, a tube of high-temp caulk, an insulation kit (25 ft of 1/2" thick insulation, adhesive, and wire mesh) and a one-piece combo wind screen/storm cap that screws onto my top tile and pivots open for cleaning, all for $700 delivered. Going to get a permit tomorrow and sheet metal to start the lower block-off plate.

Sounds great - keep us posted on your progress!

Gooserider
 
Gooserider said:
castiron said:
Update......I picked-up my Jotul C450 insert at the dealers the other day ($2154 plus tax) and took it home. It's sitting in my living room awaiting delivery of my liner and my installing it. I bought 20 ft of 6" 316Ti ss, a stove connector, a tube of high-temp caulk, an insulation kit (25 ft of 1/2" thick insulation, adhesive, and wire mesh) and a one-piece combo wind screen/storm cap that screws onto my top tile and pivots open for cleaning, all for $700 delivered. Going to get a permit tomorrow and sheet metal to start the lower block-off plate.

Sounds great - keep us posted on your progress!

Gooserider

Update.....I went to the city inspectors office to apply for a permit to install the insert and the inspector happened to be there and he told me none was needed. At first I thought he didn't hear me correctly so I explained what was there now (old Buck Stove Insert) and what I was planning on putting in (a new EPA approved WB insert) and he said again, no permit was required.....so, slightly amazed, I'm now only awaiting liner delivery so that I can begin the install....
 
castiron said:
Gooserider said:
castiron said:
Update......I picked-up my Jotul C450 insert at the dealers the other day ($2154 plus tax) and took it home. It's sitting in my living room awaiting delivery of my liner and my installing it. I bought 20 ft of 6" 316Ti ss, a stove connector, a tube of high-temp caulk, an insulation kit (25 ft of 1/2" thick insulation, adhesive, and wire mesh) and a one-piece combo wind screen/storm cap that screws onto my top tile and pivots open for cleaning, all for $700 delivered. Going to get a permit tomorrow and sheet metal to start the lower block-off plate.

Sounds great - keep us posted on your progress!

Gooserider

Update.....I went to the city inspectors office to apply for a permit to install the insert and the inspector happened to be there and he told me none was needed. At first I thought he didn't hear me correctly so I explained what was there now (old Buck Stove Insert) and what I was planning on putting in (a new EPA approved WB insert) and he said again, no permit was required.....so, slightly amazed, I'm now only awaiting liner delivery so that I can begin the install....

Tell Elk - we keep telling him that it seems not all places require permits - he keeps insisting a permit is needed to do a safe install....
 
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