UPDATE: New Stove in Living Room - Going with a BK Ashford!

[begreen]

An insert in a masonry fireplace goes on the assumption that the fireplace floor is non-combustible, all the way through. So under the insert is not an issue. Hearths however have a lot more variables in construction and height. The concern for the insert is heat radiated from the front of the stove where it is the strongest. If the hearth is elevated enough then it will shield the floor from the radiant heat and only ember (spark) protection is needed. But if the hearth is flush, then additional protection is needed from the strong radiated heat out to at least 16-18" in front of the insert door.

FWIW I would rather have the Durock layers under the insert and stone than just micore. The cement board is more rigid and mortar or thinset bonds much better to it.

 

[Nelson]

Thanks begreen. That was my assumption but I still find it odd that they specifically say underneath the insert as well as out in front. Out in front makes sense. It was the underneath part that was causing me pause.

It's one piece of stone that we are using for the hearth (out in front of the stove) so it just needs to sit in place. We are will likely frame this in so that it is nearly flush with the floor so I'm not concerned about it moving around or needing to accept mortar. The stone slab will just sit on top of the Micore and the Micore will sit on top of existing cement that extends out (which currently has the existing brick laid on top of it). You can see what it looks like in the pics in my first post. Hopefully that makes sense. Appreciate the advice!

Here's a pic of existing.



Assumption is that there is a layer of cement under those bricks at floor level. I have confirmed that they are full bricks as well. The other thing we may do (suggested from the stove installer) is just put micore over the existing brick and then put the stone slab on top of that. However, we are hoping to keep a more flush look with the stone slab (also replacing carpet with wood flooring and would like to butt wood flooring up to the stone slab).

 

[begreen]

I can only interpret the "under the appliance" statement as meaning the full hearth starting under the ashlip. The fireplace floor already exceeds the requirement.

 

[Nelson]

Super rough idea of what we are thinking with the one piece of stone...

 

[Nelson]

I can only interpret the "under the appliance" statement as meaning the full hearth starting under the ashlip. The fireplace floor already exceeds the requirement.

and that's where my head was going - re: the fireplace floor already exceeds the requirement. I submitted a note to Blaze King to see if they can clarify. I'd like to make sure that I can consider the fireplace floor as meeting the requirement. If I need to, I can put micore in there as well but would rather not as it may cause me to have to build up the stone piece further to make it level.

 

[begreen]

It sounds like a minor slip up on the documentation person's behalf. I used to do some formal documentation reviews and there always are a few things that get by, even trained eyes.

 

[Highbeam]

Micore sounds great if you can find it. I could not find it locally so had to use other materials.

 

[Nelson]

Micore sounds great if you can find it. I could not find it locally so had to use other materials.

I think I can order it online through Menards. Out of curiosity, what materials did you end up using?

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[Highbeam]

I think I can order it online through Menards. Out of curiosity, what materials did you end up using?

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I used steel studs and an air gap. It was an elevated hearth under a freestander. My latest hearth build with my bk thankfully only required ember protection.

 

[Nelson]

I used steel studs and an air gap. It was an elevated hearth under a freestander. My latest hearth build with my bk thankfully only required ember protection.

Nice - I'm starting to wish this was a raised hearth. That said, if I can find some Micore, I think I should be squared away.

 

[Nelson]

Ugh, feel like I'm beating a dead horse here but I want to make sure I get this right the first time. Below is a pic of what I believe the general set up is. The Ashford is going in the upper fireplace. I think my remaining question is how thick is that hearth extension (circled in green). If that is thick enough (plus whatever little R value the natural stone slab will get me) to meet the R1.06 requirement, and extends out 16" from the front of the stove door, then I would not have to use the Micore. I'm fairly certain it won't extend out 16" from the stove door so it might be a moot point. However, at least I have a better idea of what the overall chimney/fireplace set up is.

 

[begreen]

Unfortunately the word hearth can mean both the floor of the fireplace and the area in front of the fireplace. That is why the documentation is confusing. What is circled in green is both the fireplace floor and the hearth. You don't need to boost the insulation value for the fireplace floor. It already exceeds the requirement.
The fireplace floor is firebrick on top of masonry. It is not the issue for heat protection. It is designed for the constant heat of a hot coal bed. I believe the hearth as described in the manual is the red area here.

 

[Highbeam]

And area below the fireplace floor is 10’ or more deep all masonry which ought to meet the r value.

 

[Nelson]

Well, it took a little bit longer than anticipated (which it always does) but here is the final product. I have burned 3 fires in the Ashford, all at different times so I really haven't had a chance to put it through the paces. That said, I can already tell that I'm going to like this stove. I am right around 15' of pipe so i will be interested to see if I have any draft problems trying to burn at the lower levels (have not yet tried to run it below medium) but that testing will have to wait until the fall.

 

[begreen]

That looks great. It's quite an update from the old insert. I look forward to your reports next winter.

PS: Time to add the Ashford to your signature.

 

[bkon73]

Hi Nelson,

I just purchased the Ashford 25 and came upon your earlier posts while trying to resolve the same hearth issue. My install will be exactly like yours, except without the shroud along the front. Would you please share what you used for your hearth to achieve the R value? From the pictures it looks like solid stone, I don't see other layers below. I'm also curious how you built the bump out, did you need R-Value to surround the Ashford 25 on the sides and the top? If so, what did you do for that? Lastly, how does it perform? Thanks so much for your time and guidance.

 

[begreen]

bkon73, that was for an existing fireplace. What is currently in place in your home? If this installation will be from scratch it would be best to start a new thread with some pictures of what is existing and a sketch of what is planned.

 

[Nelson]

Hi Nelson,

I just purchased the Ashford 25 and came upon your earlier posts while trying to resolve the same hearth issue. My install will be exactly like yours, except without the shroud along the front. Would you please share what you used for your hearth to achieve the R value? From the pictures it looks like solid stone, I don't see other layers below. I'm also curious how you built the bump out, did you need R-Value to surround the Ashford 25 on the sides and the top? If so, what did you do for that? Lastly, how does it perform? Thanks so much for your time and guidance.

As Begreen mentioned, it may depend on what you are starting out with. I did end up putting micore down and then the solid stone slab on top of the mi-core. I don't recall the R-value of the mi-core but I did the calcs to make sure it was supported by Blaze King. If you are going in to an existing masonry fireplace, you should not need to do anything on the sides or top. However, like Begreen said, it will all depend on what you have in place currently and starting a new thread will be most useful in getting the answers you need.

 

[bkon73]

As Begreen mentioned, it may depend on what you are starting out with. I did end up putting micore down and then the solid stone slab on top of the mi-core. I don't recall the R-value of the mi-core but I did the calcs to make sure it was supported by Blaze King. If you are going in to an existing masonry fireplace, you should not need to do anything on the sides or top. However, like Begreen said, it will all depend on what you have in place currently and starting a new thread will be most useful in getting the answers you need.

Thanks for your quick reply, this is awesome! May I ask what you used to fasten the stone to the Micore? After a few years, how happy are you with the Ashford insert?

 

[begreen]

Mod Edit: bkon73's project moved to a new thread here:

Modifying a fireplace for new insert

Mod EDIT: Subject moved to it's own thread. Moved in one year ago with an existing fireplace and caution from the previous owner not to use. Upon inspection I've discovered the chimney cap is shot, mortar between clay segments of the flu is missing, the firebox needs repointing. Started...

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