Help- screwed up hearth for my Heritage

[chuckn]

Well I didn't read my R requirements correctly for floor protection on my Heritage, and now I've got a real issue. I built a real nice stone covered hearth pad for my rear vent installation. Only I thought I only needed ember protection like the Mansfield stove. I'm going through the wall with a thimble to an outside class A chimney, so I've already cut my hole and built my 5 foot high stone wall protection too. (I have good clearance to the wall with rear heat shield).

But now I see the R 1.2 spec for the floor. I built a 2x4, 12" on centers (on edges) raised hearth frame, over which I placed some left over 5/8 plywood, then 1/2 inch Duorock Next Gen, then 1/2 inch mortar, and 1.5 to 2 inch thick flat limestone. Looks great!

Only problem is its not R 1.2 I guess. So now I have a perfect thimble hole height (with about 3/8 inch of incline to outside) and stove looks great sitting up on this stone hearth and wall. So do I need to put a thin black stove pad or make something out of thin Micore to put under stove to up the R value? Or do you guys think this will suffice as is?

Haven't fired it up yet and don't want to tear out all my stonework- is there a 1/4 inch or 3/8 inch material that would give me my needed R boost? Or am I screwed.....I created this little dilemna- so Im kicking myself- would have been real easy to have added a half inch of something on the duorock- oh well....help?

 

[chuckn]

Nothing guys??

 

[begreen]

Maybe build a raised deck for the stove on top of this hearth? If done right, it could include wood storage.

 

[chuckn]

Maybe build a raised deck for the stove on top of this hearth? If done right, it could include wood storage.

That would be nice, but I have a rear exit thru a thimble and thru stone - that hole would then be too low. So i'm thinking just stick something rather thin under the stove so my hole thru the wall still works- what material- I don't know....

 

[begreen]

Sorry. I can't think of anything under 1/2" that is going to give you the required R value. And that material is far to soft for the stove to sit directly upon.

 

[chuckn]

Well I was thinking of just fitting right under the stove, a piece of something like mineral board or micore. I could cut to fit right in between all the legs. This would help reduce heat transfer right under the stove I guess, while letting me keep the stove at its current height. I could paint the piece black with stove paint so it would match the stove. Kind of messes up the clean lines of the stone, but you still see plenty of that. Any other ideas?

 

[nate379]

If you could light the ply on fire, or even smolder it though 2" of rock and 1/2" mortor I'd give you 100$ Not going to happen.

Install stove and enjoy the fire.

 

[chuckn]

If you could light the ply on fire, or even smolder it though 2" of rock and 1/2" mortor I'd give you 100$ Not going to happen.

Install stove and enjoy the fire.

Yep. Thanks Nate. Actually its 1.5 to 2 inches of stone, 1/2 inch Duorock, and 1/2 inch mortar plus mortar pointed flush in all joints....

I guess Im over worrying this. Because my wife just recalled our old farm house from our younger years where we had a monster cast iron stove (dont recall the brand) bascially sitting on a 1.5 inch x 4 foot wide piece of slate - loose on top of old hardwood floors. We used to get that stove glowing red on cold winter nights and never had an issue (that we know of). We were younger , dumber then- but no house fires.

 

[southbalto]

Two options....

If you're going to leave the stone in place you're going to have to live with the fact the hearth is not up to manufacturers specs/code. You may want to lay some micor under the stove but another option that might help you sleep at night would be to fabricate some sort of heat shield. My Castine requires some r value for the hearth but it's not necessary if the optional heat sheild is used.

Second option would be to tear out the existing hearth. I imagine you could replace the existing hearth, which is roughly 3", with materials that get you the r value you need.

 

[chuckn]

I think a sheet of Micore underneath the stove would work. Im going to be really hared pressed to tear out what I've done...we are trying to get this house done before the snows come here in VA mountains. I do have a ash pan underneath which is supposed to buffer the heat, a little like bottom heat shield. I may burn it and take some temp readings first.

 

[chuckn]

Just talked to my dealer and he said just to run it and give it the old hand test for a few burns...then if its too hot for the hand, fabricate a piece of sheet metal to slide under stove with 1/2 inch or 1 inch legs on it- like a little tray. Paint it to match stove. This is effectively a bottom heat shield that just sits under stove. He said he thought what I had would be just fine- but to test it.

 

[begreen]

Are you getting inspected and insured for this installation? If so, that is the deciding factor, not the dealer. I suspect you may be ok, but it is ultimately up to you. Did the dealer offer to cut a sweet deal on a Mansfield?

 

[nate379]

Have been in places that had nothing more than a piece of sheetmetal under the stove on top of the floor boards. Now that probably wasn't the best thing in the world, but though houses are still there now so I guess it's fine?

If you ask me, the R value and all that b/s is just a mega CYA for the stove company.

 

[begreen]

Right, what stove company likes to miss a sale because the tested hearth requirements are too stiff? All stoves are not created equal. Some radiate a lot more heat from their bottom than others. I've had stoves that need virtually no hearth and others that you could cook an egg under.

 

[Dakotas Dad]

Let's see.. the engineers who designed it and tested it, give you a number that is a MINIMUM... and you are not any where close to that number. Sure they have a safety factor. So should you.

You, your family, all your things.. in this house. Insured? really well? well enough that you think they will pay if you burn your house down because you didn't follow the manufacturers requirements? Life insurance paid up? Just in case your family survives and you don't.

Sure, lots of people have crappy installs and still don't burn their house down. Others aren't as lucky.

I am sorry it's messed up. But GLAD you saw the problem before using it. Only ONE answer in my world. Be the man, do it right, tear it out, do it properly.

 

[madison]

Depending on the dimensions of your current hearth, would a Mansfield fit the clearances to the walls and front of hearth? If yes, it would ""only"" require removing the wall stone. and moving the thimble. Saving the hearth floor stone work. I would think the dealer would take a trade in on an unused stove upgrade....

And is this connecting to an existing tiled chimney, or a new exterior class a? Pictures and a complete diagram of the home and hearth might get some better responses.

I would personally have the issues corrected, and would not want the liability of torching my family, OR if you attempt to sell the home, incurring the legal liability issues associated with your improper DIY work.

 

[nate379]

Guys use some common sense. I don't care what stove company xyz says, like I said it comes down to CYA, just like the Stihl book with a chainsaw is 40 pages, mainly all safety stuff, and they want you to use the safety chain, 80lbs of PPE, etc.

Take that 3" thick slab of rock, mortar and Durock and heat that up with a 6000* torch. I bet you run out of gas in the tanks before you can feel it get warm underneath. Now compare to a stove which is going to get what, 600-700* at the most?

No I'm not an engineer but I have met many that were dumber than a box of rocks. Only knew "by the book" and had no clue about the real world.

I'm not going to pretend to know all stoves out there, but we used to heat a camp with a cheap box stove that sat about 10" above the wooden floor (old planks). All we had was a thin piece of sheetmetal to protect the floor, and we had that stove glowing cherry red many times. Floor was fine when the stove was removed about 10 years later to replace it.

 

[Dakotas Dad]

Take that 3" thick slab of rock, mortar and Durock and heat that up with a 6000* torch. I bet you run out of gas in the tanks before you can feel it get warm underneath. Now compare to a stove which is going to get what, 600-700* at the most?

Hmmmm.. I wonder then how my stone stove is able to get 600 degrees and climbing in 30 minutes from a reload, with a fire way below 6000 degrees?

It's one of those things.. My seat belt has never saved my life yet I wear it everywhere. Many choose not to. And many don't die because they weren't wearing one. But people do die everyday because they weren't..

Now, my motorcycle helmet has done it's job twice.

Without even really getting into the insurance ramifications of a fire where the investigation may find a less than stellar install , the safety and well being of my family far out weigh any desire to prove an engineer or two wrong.

 

[nate379]

Insurance isn't going to not pay because your hearth was only an R1.5 instead of R1.65 or whatever. It's there to protect idiots just as much as it is there to help out with accidents.

 

[Rob From Wisconsin]

I faced the same problem when I changed my stove out to a Hearthstone.
Almost no stove require such a beefed-up heathpad!
So I did some temp. measurements beneath & around my stove & found that the
"hot" spot was mainly right under the stove.
Placing a piece of cement board w/ 1/2" spacers underneath seemed to help quite a bit.
Micore should work even better.

 

[Dakotas Dad]

Insurance isn't going to not pay because your hearth was only an R1.5 instead of R1.65 or whatever. It's there to protect idiots just as much as it is there to help out with accidents.

Wrong. My wife was an insurance agent, then adjuster, before going into the IT side of insurance. I can slap damn gurentee if someone has a fire brought about by an obviously faulty self install, they won't pay. Seen it.

In this case of the OP his Rvalue is less than 10% of the manual requirement. Believe me, Insurance is business, not a service, and they have to protect their investors, which means if YOU burn your house down, due to a fault YOU should have known of and corrected, they will not pay, or at best, pay a reduced amount, and drop you like a radioactive potato.

 

[Todd]

What about contacting Hearthstone and asking them if an extra heat shield is ok? Maybe they can give you something in writing to please the insurance company?

Also like Madison's idea, maybe dealer will work with you on a different stove?

 

[CarbonNeutral]

No I'm not an engineer

There you go, by self admission. This is terrible advice.

Who even cares about insurance paying out if your family has died of smoke inhalation?

It isn't about instant heat, and how quickly you can transfer heat. We're talking about 400-500 degrees over a period of hours, days, and years. In a matter of hours the heat will be transmitted to the wood and combustibles. Over a period of time the chemical structure of the material will change, making it much more likely to catch fire. Google pyrolysis.....

You need to get this sorted out - either with a different stove (Jotul F500 is ember protection only) or by ripping it out.

 

[chuckn]

Well Hearthstone doesnt talk to consumers- so my dealer in VA- Acme Stove- big here in Western VA - was confident I was ok- especially fabricating the heat shield....and they sell and install hundreds of Hearthstone units per year....so no rip out.

 

[cptoneleg]

Which town are they located. This Acme Stove.