Limestone or Reclaimed firebrick or flagstone under a wood stove?

[philraymond]

I've seen mention of using limestone underneath a wood stove despite the fact that limestone allegedly cracks from the heat.

My question is whether that cracking is a problem. If I'm using irregular rock shapes anyway, it won't disrupt the aesthetic much.

Any thoughts?

(I'm getting a Pacific Energy Super LE. My understanding is that is needs only a non-combustible pad underneath, not a specific r-value.)

 

[philraymond]

Would this old firebrick work for a hearth pad (under a new Pacific Energy Super LE)?

(broken link removed to https://www.kijiji.ca/v-renovation-flooring-wall/city-of-toronto/historical-reclaimed-firebricks/1572065781)

Since that link will eventually stop working, I'll attach photos below.

 

[begreen]

Yes, they're ok. The hearth should have a sheet of metal or cement board underneath if dry-laid as a barrier in case an ember falls between the cracks.

 

[SteveKG]

Cannot think of a reason why not. I used some years ago in building the floor of a large fireplace and it is still perfectly fine.

I also have a few left and use them on which to solder stuff and even make cuts with a torch. Just for an extra handy use.

 

[brenndatomu]

Pacific Energy Super LE. My understanding is that is needs only a non-combustible pad underneath, not a specific r-value

A thin piece (1/8") of steel works too...

 

[begreen]

A thin piece (1/8") of steel works too...

Could even be glass or 24 ga, hemmed sheet metal as long as it is a non-combustible ember barrier that covers the hearth requirements in the manual.

 

[philraymond]

Thanks, yes, I considered that. I was thinking the thermal mass of brick or stone underneath and behind the stove would be worth the extra time and expense.

 

[philraymond]

Cannot think of a reason why not. I used some years ago in building the floor of a large fireplace and it is still perfectly fine.

I also have a few left and use them on which to solder stuff and even make cuts with a torch. Just for an extra handy use.

It looks like a moderator combined my 2 posts into 1. Are you referring to the brick? Thank you.

 

[Highbeam]

Only a few stoves still require a hearth material with any insulative value. It's an archaic requirement from the old days when stoves released a lot of heat downward.

Your stove, correct me if I'm wrong, only requires ember protection which means that it could sit on top of a piece or super thin HVAC style sheet metal with plywood floor sunder that. The only rule is that you need a noncombustible membrane for errant sparks.

On the wall behind and beside the stove you have a clearance to combustible specification for the stove. Outside of that distance you can have bare plywood walls, zero noncombustibles are required.

The old days of big brick hearths being required are gone. Modern stoves can safely and legally be installed with very little peripheral construction. For aesthetics and an extra margin of safety you can build all kinds of brick and stone hearths.

I just have painted sheetrock 6" behind my blaze king. I would like to improve the wall for aesthetics.

 

[begreen]

The old days of big brick hearths being required are gone. Modern stoves can safely and legally be installed with very little peripheral construction.

Lest someone later on reads this wrong, make that many modern stoves. There are still some that require greater than ember protection including several Woodstock stoves, the Englander 32-NC, etc.

 

[Highbeam]

Lest someone later on reads this wrong, make that many modern stoves. There are still some that require greater than ember protection including several Woodstock stoves, the Englander 32-NC, etc.

Those don’t require big brick hearths either but do still have an archaic hearth floor insulation value requirement that can be met with some modern thin foam materials but I get your point. Check each stove. It’s specified in the manual.

 

[EbS-P]

If you want a

I was thinking the thermal mass of brick or stone underneath and behind the stove

It also takes longer to heat up. My stove sets inside my fireplace and it takes 12 hours to get the stone hot. I’d do it for looks before I would do it for thermal mass. Brick just isn’t that high relative to cast iron. That amount of brick is a very small percentage of the thermal mass of the house. And unless you sit right next to the brick I’d rather have the heat in the house.

 

[philraymond]

That amount of brick is a very small percentage of the thermal mass of the house.

Thanks, yes, that's what I've been learning with subsequent reading. Apparently, adding thermal mass may be warranted in some cases, but a small stone wall behind the stove isn't going to do much - you need a LOT of stone to make a difference. I've read that adding insulation and fixing air leaks is probably a better investment in an old house like mine.

 

[philraymond]

I'm building a simple hearth of flagstone over cement board. If I get big pieces of flagstone (i.e. heavy), can I just place them without wet-laying them? Or will I regret it?

Edit: The stove needs only ember protection - the flagstone is mostly for aesthetics.

 

[xman23]

First check what the stove manual says the hearth needs to be. But I would make the hearth as smooth as possible for cleaning.

 

[Rob_Red]

I am running a piece of flag stone just as you described with no issues. I did space it off the floor slightly with some stainless washers. Cleans perfectly fine with a hand broom, a spounge and some dish soap gets any stains out.

has been working perfectly, in fact I just moved it and there was zero floor damage underneath.

I did not use any sealer on the stone.

love the look and it’s was cheap, do consult your stove manual to make sure there is no required R value

 

[clancey]

I love flagstone..I do not know if this would fit the same idea but basically I wanted the concrete layers on the porch to lay me a separate 4 inch high square piece under my stove that would just sit on the concrete by making a form. I wanted a pretty color added to it and it would raise it up higher so I would not have to bend so low to put wood in it. My stove installer "thumbs down" this idea of mine "unless" It was part of the concrete floor or bolted down for he did not want it movable. So I just sat the wood stove on the concrete floor without my "great idea"--lol clancey

 

[philraymond]

I am running a piece of flag stone just as you described with no issues.

Thanks for sharing. Just 1 big piece of flagstone?

 

[Bad LP]

If your worried about it moving for whatever reason some small dabs of silicon will prevent movement.

 

[Rob_Red]

For me yes one big piece 3.5’x3.5’ about 2 inches thick. I have a smaller stove though.

also my floor is also stone tile and therefor non combustible so I’m double covered. Like you my stove (hearthstone) specifies the need for ember protection only.

 

[begreen]

Moved to previous thread.
This same question has been asked now for 3 different materials. The answer is the same for each material. If no mortar then there needs to be ember protection below the material unless the material is one piece.

 

[philraymond]

This same question has been asked now for 3 different materials.

Thanks for your help. To me, it was 3 different questions, and for the benefit of future searchers, it's usually best practice to ask one question per thread (although if hearth.com prefers to have them all together, that's okay with me).

For the most recent question about dry-laying the flagstone, I'm not thinking about ember protection but rather the other ramifications of having no mortar, like will it cause structural problems or general annoyance to me. Thanks!

 

[bholler]

Thanks for your help. To me, it was 3 different questions, and for the benefit of future searchers, it's usually best practice to ask one question per thread (although if hearth.com prefers to have them all together, that's okay with me).

For the most recent question about dry-laying the flagstone, I'm not thinking about ember protection but rather the other ramifications of having no mortar, like will it cause structural problems or general annoyance to me. Thanks!

The need for bedding mortar will depend upon the thickness and uniformity of the material.

 

[begreen]

The need for bedding mortar will depend upon the thickness and uniformity of the material.

And the flatness of the surface it is being placed on.

 

[philraymond]

Update: I ended up finding a big piece of flagstone that was nearly the right size. I had to get a diamond blade for my angle grinder to make 1 cut, and then get 3 other guys to help me bring it in the house, but I'm happy with it. I didn't mortar it in - will see how it holds up. Thanks to everyone for the tips!