Flush hearth extension for wood stove

[Zoso2385]

Hi all,

I will be installing Jotul F500 outside my existing masonry fireplace. Right now I have Engineered wood floor with a hearth that is flush with the floor. I would like to extend the hearth maybe 20” to have proper clearances of non combustible’s. I really can’t higher or the stove pipe will not fit into the fireplace opening. Looking for ideas or any contractors that could help in Connecticut

 

[Zack R]

I had to do something very similar, albeit it was before I installed the laminate wood floor. I'd recommend the following:

- Figure out the clearance requirements of the stove you would like to use
- Tape off this space with masking tape so you have an idea of size
- Call a local installer to come out and confirm that a stainless liner will fit, see if they have a test piece that can be shoved up the chimney. The damper will likely need to be cut out at this time. Also check if a short leg kit will be needed.
- Once you have the green light to proceed then go look at tile to see what you like, order enough for the whole job (including grout, etc..)
- Remove the four existing tiles
- If the floor is click together take it apart as best as you can to make room for the tile (floor experts chime in here)
- Once the floor is removed in the area that will be tiled then lay down some cement backer board for the tile to sit on
- Lay the tile, grout, etc
- Once the tile is set then tidy up the wood floor so that it meets the tile cleanly (floor experts chime in here)
- Have the stove installed, be sure to seal off the chimney opening (besides where the liner goes through)

 

[EbS-P]

The short leg kit will save you 2-1/4” if you need a little more space. If you haven’t considered them already.

Evan

 

[mstoelton]

Unless you are only looking for ember protection the plan outlined above is not complete. The R-value of the tiles and the cement backer board are not high enough and you will need to install something below the tile with a higher R-value to truly be in compliance.

 

[Zoso2385]

So I have taken some of those steps.

-There is 27” of clearance floor to lintel, the F500 will fit with the short leg kit installed.

-The existing flue is 12x12 clay tile

- I have ordered an insulated 6” SS liner and have the first 4ft ovalized to 5” to fit through the damper door.

-I have the sheet metal to build a block off plate and Roxul to insulate it.

One thing I have not done is decided if I want the stove to sit inside the fireplace a few inches or sit completely outside the fire place. The existing flooring is not laminate it is engineered hardwood which is more like a thick veneer of oak on top of cross crossed plywood, I’m not sure how it fastened to the floor right now. Also the existing stone looks to be about .5” to .75” thick and I’d like to use the same stuff to extend it, just not sure where to get it


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[Zoso2385]

Mstoelton, I was looking in the manual for the stove and I cannot find where any R value is required under the stove, as I believe there is a heat shield underneath it. Please correct me if I’m wrong


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[bholler]

Mstoelton, I was looking in the manual for the stove and I cannot find where any R value is required under the stove, as I believe there is a heat shield underneath it. Please correct me if I’m wrong


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I am sure there is an increased r value required when using the short leg kit. And to be truly to code your extension would need to be built to meet code requirements for an open fireplace. That means it needs to be a minimum 2" slab with no combustibles contacting the bottom side of it.

Also don't ovalize through the damper cut the frame out.

 

[Zack R]

I vote to have the stove fully outside of the existing fireplace. It'll look better and will more effectively radiate heat into the room.

For the floor I'd consult with a local stove installer and or floor installer to see what they have done. Since its actual wood you could probably just mask out the area you need and cut to depth with a circular saw, then add trim where it interfaces with the tile.

Note - don't cut the cement backerboard inside the house, it makes a huge mess!

 

[Zoso2385]

I’ve thought about cutting the damper out, I have an angle grinder but I’m just not sure how to tackle it, cut the frame in severe places and yank out?


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[bholler]

I’ve thought about cutting the damper out, I have an angle grinder but I’m just not sure how to tackle it, cut the frame in severe places and yank out?


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You usually don't have to take the whole thing out. Normally just a part of the back section is enough.

 

[Zoso2385]

But what about the damper door, the hinges are not accessible they are behind the assembly.


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[bholler]

But what about the damper door, the hinges are not accessible they are behind the assembly.


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Take a picture of your damper and I can give you better input

 

[Zoso2385]

Take a picture of your damper and I can give you better input

I’ll snap a picture when I get home from work. Thank you


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[Zoso2385]

Here’s a pic of the damper

 

[bholler]

Here’s a pic of the damperView attachment 240291View attachment 240292


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That damper plate should just lift out and notching the back should give enough clearance for 6"

 

[Zoso2385]

That damper plate should just lift out and notching the back should give enough clearance for 6"

Thank you, it never occurred to me that it could just lift out. That will make the liner install much easier.

Now I just have to figure out what kind of R value is required under the stove. I really don’t want to raise the floor




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[Zoso2385]

Unless you are only looking for ember protection the plan outlined above is not complete. The R-value of the tiles and the cement backer board are not high enough and you will need to install something below the tile with a higher R-value to truly be in compliance.

Found this in the manual for the F500, I will call Jotul, but it seems like ember protection is all that’s required

 

[bholler]

Found this in the manual for the F500, I will call Jotul, but it seems like ember protection is all that’s required

View attachment 240293

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Yes but that is with full length legs I am sure the requirement increases with the short leg kit.

 

[Zack R]

Yes but that is with full length legs I am sure the requirement increases with the short leg kit.

What about a rectangle insulated hearth pad? Could this sit directly on the subfloor without a concrete backing board and provide enough R value?

 

[Zoso2385]

What about a rectangle insulated hearth pad? Could this sit directly on the subfloor without a concrete backing board and provide enough R value?

If I raise the stove at all the stove pipe won’t fit into the fireplace opening


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[bholler]

What about a rectangle insulated hearth pad? Could this sit directly on the subfloor without a concrete backing board and provide enough R value?

Yes if it is a non permanent extension it just has to meet r value of the stove. But a permanent extension needs to meet code for a fireplace

 

[Zoso2385]

Yes if it is a non permanent extension it just has to meet r value of the stove. But a permanent extension needs to meet code for a fireplace

Wouldn’t a permanent extension still meet code for a fireplace? The stone that is on my floor now is on top a concrete slab. If I added more stone in front of that i wouldn’t be destroying what is already there (not saying I want to do that)


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[weatherguy]

If I raise the stove at all the stove pipe won’t fit into the fireplace opening


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You dont have any play at all? What's the distance between floor and lintel?

 

[bholler]

Wouldn’t a permanent extension still meet code for a fireplace? The stone that is on my floor now is on top a concrete slab. If I added more stone in front of that i wouldn’t be destroying what is already there (not saying I want to do that)

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No a permanent hearth extension for a fireplace even if it is oversized needs to meet code requirements for a fireplace

 

[Zoso2385]

You dont have any play at all? What's the distance between floor and lintel?

Distance is 27”. With the short leg kit the top of the rear exit flue would be 26.25” so .75” clearance and at that it would be scrapping the lintel


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