For those of you that have the hearthstone mansfield is a hearth dimension of 74" w x 39 " d good enough.I made my decision to buy the mansfield but after looking at the hearth requirements I am not to sure now.I am sure the heritage would work fine but i kind of had my heart set on the mansfield.I plan on using 6" double walled pipe and a rear heat shield.
hearthpad requirements
- Thread starter traveler659
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
You've got PLENTY of width, but you're about 7" short on the depth.
You either have to increase the size of the hearth pad or decrease the size of the stove.
That being said, these are guidelines that NFI certified installers MUST adhere to & if you're
gonna have the installation inspected for code compliance & insurance reasons, there's
no getting around these requirements.
If you're forgoing the inspection, hey, it's your life, your family's life & your home...
I'm just sayin...
You either have to increase the size of the hearth pad or decrease the size of the stove.
That being said, these are guidelines that NFI certified installers MUST adhere to & if you're
gonna have the installation inspected for code compliance & insurance reasons, there's
no getting around these requirements.
If you're forgoing the inspection, hey, it's your life, your family's life & your home...
I'm just sayin...
Agreed. This is not a place to skrimp. The hearth should extend a minimum of 18" in front of the stove glass. No problem with it extending even further. A generous hearth is also nice for containing the ash and bark debris.
http://www.chimneysweeponline.com/chsmans.htm
http://www.chimneysweeponline.com/chsmans.htm
OK guys let me explain my hearth for a minute.It is a 2x6 frame,with a sheet of 1/2" plywood over the top,than a sheet of 1/2 gypsum board over the plywood, surrounding the frame is 1x8 trim wood.The entire top of the hearth is layed with 1" thick stone and has an overlap of appx 1".The hearth is not attached to the wall so it can be moved back and away from the wall.By sliding the hearth back lets say 8" this will give me a total depth of 47 inches.The only thing I am wondering is the 8" of exposed floor behind the stove.The hearth is 9" tall. Do you guys think this would be ok.
First thing to do is to read up on the hearth requirements. Hearthstone stoves have higher R value requirements than some stoves. The Mansfield is R=.8, Heritage is R=1.2.
When you say that the current hearth has gypsum board underlayment, do you mean cement board or gypsum wallboard? It should be cement board. If it is, the insulation value for the cement board + slate is around R=.36 which is not up to the requirement for the Mansfield.
When you say that the current hearth has gypsum board underlayment, do you mean cement board or gypsum wallboard? It should be cement board. If it is, the insulation value for the cement board + slate is around R=.36 which is not up to the requirement for the Mansfield.
Be green is correct about the R value. You dont need 18" from the stove glass on the Mansfield, only 16". (Some inspectors are still stuck on the 18" rule from back in the 70s and will want to see that. You do need 6" from the back of the stove. So, take 6" rear hearth requirements, depth of stove and 16" in front and you end up with about 46-47" depth of the hearth pad that all needs to be r.8. Theres many places where you can find the R value of different materials. Different 1" stones have different R values. An example of a proper hearth for the Mansfield with 1" thick slate should be (assuming 1/2" thick Gypsum has an R value of .45) @ layers of Gypsum and 1" of slate. If you use wonderboard or another type of cement board, which I think has a .2 r value, you would need 4 layers of cement board + your 1" slate. I may be wrong here, but thats the chart I think I always went by.
Either way your depth is not enough.
Either way your depth is not enough.
Yes you are correct. I had the 2003 Hearthstone manual which listed 16". My bad to assume they had updated the spec after the 2007 NFPA ruling. The new NFPA code passed is 18" in front of the glass. However, based on an update a while back posted by Tom, if the mfg. tests and certifies the stove at 16", it is allowed. For the Mansfield I think traveler can get away with 3 layers of durock = R .78 and 1" slate comes in at .1 for a total of R=.88
https://www.hearth.com/econtent/index.php/forums/viewthread/9142/
https://www.hearth.com/econtent/index.php/forums/viewthread/9142/
Are you sure about the Mansfields spec? I'm not trying to play gotcha but, I have been looking at the manual for this stove because we decided to use the Mansfield instead of the Heritage like we originally thought.BeGreen said:
When I was looking at the manual specifically for the hearth pad requirements it looked a little vague.
"The unit must be placed on a *non-combustible floor
protector that extends 16” in front and 6” to each side of
the unit. If installed in an alcove at reduced clearances
with NFPA 211 wall protection, the area in front of the
unit must have an ADDITIONAL insulative R-value of .8, or a
listed floor protection must be used.
*An example of a non-combustible floor protector would
be a hearth constructed with a continuous layer of a listed
backer board (such as Wonder-Board or Durock) used for
ember protection with a tile, brick, slate, or another noncombustible facing."
This looks like it's saying that only if the stove is placed in an alcove...it will need an ADDITIONAL R=.8 and only in front of the stove. So my question is...in addition to what. It doesn't seem logical to me that a larger stove would have less hearth pad requirements than a smaller stove like the Heritage.
stove to wall 8"
stove depth 24"
front hearth 16"
48" wall to front of hearth is rear shield, and double wall interior pipe is used.
the book is wierd, it says
An acceptable floor protector is a 3/8 (10 mm) minimum thickness non-combustible or listed floor protector with an R factor of 1.0.
but, 3/8 non combustibles would rarely come close to r value of 1.0....
stove depth 24"
front hearth 16"
48" wall to front of hearth is rear shield, and double wall interior pipe is used.
the book is wierd, it says
An acceptable floor protector is a 3/8 (10 mm) minimum thickness non-combustible or listed floor protector with an R factor of 1.0.
but, 3/8 non combustibles would rarely come close to r value of 1.0....
Yeah, thats not really so clear. I would suggest the OP contacting the dealer he bought the stove from and having them contact Hearthstone and hear it from the horses mouth. That paragraph can be read a couple of different ways. In regards to the big stove/small stove less clearance/more clearance issue..Thats common in this industry. Each stove undergoes testing and thats how they get listed. Sometimes smaller stoves will require more clearances not based on size, but on how the stove is constructed which would effect the skin temps.
I was scratching my head when I read that one too. Best to get it clarified by the dealer or better yet from Hearthstone tech support. Please let us know what they have to say.
Tom, have you run into this question?
Tom, have you run into this question?
Jim Casavant, the wood guru at Hearthstone, is on vacation, but I have gone around with him about their manuals in general and the Mansfield hearth requirement specifically, so I could get it right on my website. Here's my understanding of Hearthstone's requirements for the Mansfield:
The new NFPA hearth extension requirement of 18" in front of the loading door applies to unlisted stoves, or stoves that haven't been tested and listed to the 16" standard. The Mansfield was listed at 16", so the front of the hearth needs to be 48" from the backwall, like Dave says above:
stove to backwall 8”
stove depth 24”
front hearth 16”
BUT the rear of the heart only has to extend 6" behind the stove, not all the way to the backwall. So, a 46" deep hearth can be used, if you leave a 2" gap between it and the backwall.
There seems to be some debate about what constitutes continuous ember protection. Hearthstone suggests a listed backer board material to satisfy the "continuous" part, covered with non-combustible stone, tile, etc. to satisfy the "non-combustible" part, but the five code jurisdictions our service area spans have all ruled that one layer of grouted stone or tile satisfies both requirements. In other words, once you grout them in, bricks, tiles and stones constitute a continuous surface for ember protection purposes. YMMV: find out what your code inspector will pass before building your hearth.
The alcove hearth requirement confusion results from unfortunate phrasing: it should read something like:
If installed in an alcove at reduced clearances with NFPA 211
wall protection, the floor protection in front of the unit must have,
in addition to the above requirements, an insulative R-value of 0.8.
(or a listed floor protection must be used).
The new NFPA hearth extension requirement of 18" in front of the loading door applies to unlisted stoves, or stoves that haven't been tested and listed to the 16" standard. The Mansfield was listed at 16", so the front of the hearth needs to be 48" from the backwall, like Dave says above:
stove to backwall 8”
stove depth 24”
front hearth 16”
BUT the rear of the heart only has to extend 6" behind the stove, not all the way to the backwall. So, a 46" deep hearth can be used, if you leave a 2" gap between it and the backwall.
There seems to be some debate about what constitutes continuous ember protection. Hearthstone suggests a listed backer board material to satisfy the "continuous" part, covered with non-combustible stone, tile, etc. to satisfy the "non-combustible" part, but the five code jurisdictions our service area spans have all ruled that one layer of grouted stone or tile satisfies both requirements. In other words, once you grout them in, bricks, tiles and stones constitute a continuous surface for ember protection purposes. YMMV: find out what your code inspector will pass before building your hearth.
The alcove hearth requirement confusion results from unfortunate phrasing: it should read something like:
If installed in an alcove at reduced clearances with NFPA 211
wall protection, the floor protection in front of the unit must have,
in addition to the above requirements, an insulative R-value of 0.8.
(or a listed floor protection must be used).
Okay...that makes it a little clearer.
So let me get this straight...is the hearth pad primarily for protection against falling embers or protecting a combustible floor surface from the heat from the underside of the stove?
So let me get this straight...is the hearth pad primarily for protection against falling embers or protecting a combustible floor surface from the heat from the underside of the stove?
Yes on both counts. That's presumably why they want a greater R value in a trapped-heat situation like a minimum clearance alcove.
Why is it that the mansfield has a lower r value for a hearth than the heritage stove. The mansfield requires a .8 while the heritage reguires a 1.2 r value.The mansfield is a larger stove than the heritage, so am I missing something.I am very confused now.Also while we are on the subject the blaze king does not have a r value listed for hearth requirements all it says is a non combustable flooring material.Is it because it is lined with firebrick?
The floor protection requirement is determined by the test lab, based upon the temperature under and just in front of the stove at a high burn rate. Ember-only protection indicates that the stove in question doesn't transmit much heat downward, regardless of the size of the firebox. Tall legs or pedestals, ash drawers, and extra shielding or chambering below the firebox floor all reduce downward heat transfer and subsequently help a given model score a lower floor protection R-value at the testing lab.
If the Heritage and Mansfield were identical, the only difference being firebox size, you could expect the larger Mansfield to have the larger R-value requirement. But that is not the case. The Heritage and Mansfield are different designs, with different leg heights, different ash removal assemblies and different air intake plenums to interrupt the transfer of heat between the firebox and the hearth. The test lab's R-value requirements reveal that it gets hotter under the smaller Heritage than it does under the larger Mansfield.
If the Heritage and Mansfield were identical, the only difference being firebox size, you could expect the larger Mansfield to have the larger R-value requirement. But that is not the case. The Heritage and Mansfield are different designs, with different leg heights, different ash removal assemblies and different air intake plenums to interrupt the transfer of heat between the firebox and the hearth. The test lab's R-value requirements reveal that it gets hotter under the smaller Heritage than it does under the larger Mansfield.
I just got a reply from Jim Casavant on the question of R value for the Mansfield hearth pad requirements. I thought I'd share.
"The Mansfield does not require any r-value for the hearth pad (unless it
is installed in an alcove). It just needs to be a continuous piece of
material made to the minimum hearth dimensions (38-1/2" W x 46" D) to
provide ember protection. I'd suggest a plywood sub hearth covered with
a cement board like WonderBoard or Durock with a non combustible facing
(like brick, slate, or tile). An acceptable alternative would be a UL
listed hearth pad that meets the minimum dimensions.
I hope this is helpful.
Jim Casavant
HearthStone
Technical Data Sheet
Required R-Values For HearthStone Wood Stoves
Date: 7/12/2010 Page: 1 of 1
Stove Model Required R-Value Exceptions
Bennington 8350 Non-combustible Flooring* With Double Wall Pipe – 0.9
Shelburne 8370 0.8
Craftsbury 8390 Non-combustible Flooring*
Homestead 8570F 2.5
Homestead 8570H 6.6
Heritage 8021 1.2
Phoenix 8612 1.0
Mansfield 8011 Non-combustible Flooring* Alcove Installations – 0.8
Tribute 8040 0.6
Equinox 1.0
Morgan 1.0
*An example of a non-combustible floor protector would be a hearth constructed with a continuous layer of a listed backer board (such as Wonder-Board or Durock) used for ember protection with a tile, brick, slate, or another noon-combustible facing.
"The Mansfield does not require any r-value for the hearth pad (unless it
is installed in an alcove). It just needs to be a continuous piece of
material made to the minimum hearth dimensions (38-1/2" W x 46" D) to
provide ember protection. I'd suggest a plywood sub hearth covered with
a cement board like WonderBoard or Durock with a non combustible facing
(like brick, slate, or tile). An acceptable alternative would be a UL
listed hearth pad that meets the minimum dimensions.
I hope this is helpful.
Jim Casavant
HearthStone
Technical Data Sheet
Required R-Values For HearthStone Wood Stoves
Date: 7/12/2010 Page: 1 of 1
Stove Model Required R-Value Exceptions
Bennington 8350 Non-combustible Flooring* With Double Wall Pipe – 0.9
Shelburne 8370 0.8
Craftsbury 8390 Non-combustible Flooring*
Homestead 8570F 2.5
Homestead 8570H 6.6
Heritage 8021 1.2
Phoenix 8612 1.0
Mansfield 8011 Non-combustible Flooring* Alcove Installations – 0.8
Tribute 8040 0.6
Equinox 1.0
Morgan 1.0
*An example of a non-combustible floor protector would be a hearth constructed with a continuous layer of a listed backer board (such as Wonder-Board or Durock) used for ember protection with a tile, brick, slate, or another noon-combustible facing.
So that clarifies the writing in that manual. Very interesting. Thank you for passing the information along
I vote that Hearthstone have employee Jim write the hearth requirements for their stoves in the owners manuals beginning today. I see no reason to retain the services of the lawyer who is doing it now. Jim speaks English.
I just checked hearthstones online manual for the mansfield and they have corrected the hearth requirements. It used to be .8 it now reads ember protection only.For the alcove install it is still .8
Super. It's great that they were that responsive. Maybe Jim is reading the forum? If so, a hearty thanks!
I still think that is insane ,as we have so much heat under our New Mansfield stove and in looking at other members quotes I am thinking there may be something not right with our stove ...One man has said he feels very little heat transfer under his stove and we have way way to much ....from a couple owners reples to our stoves ,,Seems ot make sense that something isn't right ???would you agree?
Zooter, Zooter, Zooter
It's me, Tom from www.chimneysweeponline.com. From your posts here, I recognize you as the lady that E-mailed the same concerns to me a few weeks ago. We exchanged several E-mails in the days following, in which you described your hearth as two layers of Durock under a layer of ceramic tiles. You sent me a photo of your installation, showing that your Mansfield is not installed in an alcove of any kind, and that your hearth extends the required distance in all directions.
I repeatedly explained to you that your hearth is well within the tested spec for your stove. When that didn't allay your fears, I explained that there's a difference between "feels too hot" and "dangerous", and that an accredited testing laboratory has already determined that your installation is not dangerous. After several E-mails back and forth, I believed I had finally gotten through to you.
A couple of weeks later, I noticed you posting here on the forum with the same fears, as if you and I had never communicated. The forum members who responded all told you the same things I had already told you.
Now, several days later, here you are again.
Zooter Dear, I finally figured out what you should do. Lay down another couple layers of Durock on top of your existing hearth, with 24 ga. sheet metal sandwiched between. Overlay this with a layer of Wonder Board, and finish with a top layer of ceramic tile. You won't be any safer than you are now, but the next time you go down in the basement, the flooring under the tiles won't feel warm at all. And maybe you'll be able to get some sleep.
It's me, Tom from www.chimneysweeponline.com. From your posts here, I recognize you as the lady that E-mailed the same concerns to me a few weeks ago. We exchanged several E-mails in the days following, in which you described your hearth as two layers of Durock under a layer of ceramic tiles. You sent me a photo of your installation, showing that your Mansfield is not installed in an alcove of any kind, and that your hearth extends the required distance in all directions.
I repeatedly explained to you that your hearth is well within the tested spec for your stove. When that didn't allay your fears, I explained that there's a difference between "feels too hot" and "dangerous", and that an accredited testing laboratory has already determined that your installation is not dangerous. After several E-mails back and forth, I believed I had finally gotten through to you.
A couple of weeks later, I noticed you posting here on the forum with the same fears, as if you and I had never communicated. The forum members who responded all told you the same things I had already told you.
Now, several days later, here you are again.
Zooter Dear, I finally figured out what you should do. Lay down another couple layers of Durock on top of your existing hearth, with 24 ga. sheet metal sandwiched between. Overlay this with a layer of Wonder Board, and finish with a top layer of ceramic tile. You won't be any safer than you are now, but the next time you go down in the basement, the flooring under the tiles won't feel warm at all. And maybe you'll be able to get some sleep.
- Status
Similar threads
