Hampton 300 Hearth requirements interpretation.

[nlittle]

Hello again.
I am really driving myself crazy here to ensure I am SET for install.

The insert is being put into an existing masonry fireplace. The hearth is about 19" deep and is level with the carpet floor.
The stove doors will stick out 9 inches and the bottom lip 11".
This gives me a minimum of 8 inches of existing hearth in front for protection, which I know is not code.
The manual states this:

Floor protection must be non-combustible, insulating material with an R value of
1.1 or greater.
* Hearth thickness of 0.5" with k value = 0.84", R value = 6 or greater.
Thermal floor protection is not required if the unit is raised 3.5" minimum (measured
from the bottom of the stove). However, standard ember floor protection is required.
It will need to be a non-combustible material that covers 16" (406 mm) in the US and
18" (450 mm) in Canada to the front of the unit and 8" (200 mm) to the sides.
If the unit is not raised, thermal floor protection required is 18" (450 mm) in the
US and Canada.
All floor protection must be non-combustible (i.e., metals, brick, stone, mineral
fi ber boards, etc.) Any organic materials (i.e. plastics, wood paper products, etc.)
are combustible and must not be used. The floor protection specified includes
some form of thermal designation such as R-value (thermal resistance) or k-factor
(thermal conductivity).

The fire prevention guy for the town said I pretty much just need spark protection, even a hearth rug. I think not......
So, a mason is going to install about an additional foot more of hearth (flush to the floor in front of the existing hearth). By removing carpet, adding some type of backer board and tile or stone as the top layer. The stone will be continued over the brick for continuity.

From what I read here, it seems ok but this R value stuff baffles me! I guess it might come down to the raised 3.5" requirement. Does the existing built in hearth = raised the depth of a brick plus the concrete or does it not count because that same hearth is floor level??

Does this meet the manual requirements to cover me in case of incident?

Thanks in advance!
Nervous Nellie!

 

[MountainStoveGuy]

So.. if the insert is not 3.5" off the floor, then you need a rated hearth protector in front. Tile on wonderboard or plywood will not do. You will most likely need micore 160 or 300 below the ceramics to get this rating...

 

[nlittle]

OH...maybe this is generic and raised up 3.5" really means a free standing stove, not an insert...

 

[MountainStoveGuy]

No, this means that if the hearth was 3.5" below the firebox then all you need is ember protection. If the firebox is flush or less then 3.5" you need the r-value rated pad in front.

 

[CarbonNeutral]

I have a sheet of micore ceramic board that I didn't use if you are interested in buying it.....

It's the only thin material, apart from air gaps that has decent r-value and is non-combustible. 1/2" is an r-value of 1.

 

[nlittle]

Thanks guys!
This is getting difficult, but fun in it's own way!

So my insert sitting on the hearth directly does not 3.5 inches up make.
Although, the blower IS below the firebox and that is sitting on the hearth. Not sure how thick that is.
Either way I think I need the thermal rating, not just spark guard.

That being said I looked at the manual and spec sheet again and they say 2 different things
Spec sheet says: Hearth thickness of 0.5" with k value = 0.84", R value = 6 or greater.
Manual says: Hearth thickness of 0.5" with k value = 0.84", r value = 0.6 or greater.

I checked here next: (broken link removed to http://www.chimneysweeponline.com/horvalue.htm)
Looks like if I had 1" of Hardibacker or another board then I would be fine for .6.

Which R value is really required (I hope the .6) ?? The regency I2400 docs (pretty much same stove) have the same typo.
Anyone know?

Thanks!!

 

[MountainStoveGuy]

.6 will be the correct value, and wonderboard has a .20r/.5 inch of material.

 

[CarbonNeutral]

Thanks guys!
This is getting difficult, but fun in it's own way!

So my insert sitting on the hearth directly does not 3.5 inches up make.
Although, the blower IS below the firebox and that is sitting on the hearth. Not sure how thick that is.
Either way I think I need the thermal rating, not just spark guard.

That being said I looked at the manual and spec sheet again and they say 2 different things
Spec sheet says: Hearth thickness of 0.5" with k value = 0.84", R value = 6 or greater.
Manual says: Hearth thickness of 0.5" with k value = 0.84", r value = 0.6 or greater.

I checked here next: (broken link removed to http://www.chimneysweeponline.com/horvalue.htm)
Looks like if I had 1" of Hardibacker or another board then I would be fine for .6.

Which R value is really required (I hope the .6) ?? The regency I2400 docs (pretty much same stove) have the same typo.
Anyone know?

Thanks!!

I went through the exact same thing with a confusing Jotul manual, so I understand your pain

 

[nlittle]

Thanks everyone!
I feel I am on a SAFE way to install and will post pics when in progress/ done.

 

[stejus]

Here's my install which passed inspection and is up to code confirmed by installer and building inspector. They read the manual and came to the same conclusion. The HI300 sits on the fireplace floor and hearth. Because the hearth level is greater than 3.5" to the next level (the hard wood floor), I could get away with standard ember protection. I went out and purchased a brownstone rock and put that in front. I need to get a rectangle wool rug to put on the wood floor and then lay the rock on top of that. When burn season is over, the rock gets put in the garage.

I think in your case because your floor is level with the fireplace floor, you need R-value protection all the way out.

 

[nlittle]

Yeah, I kinda wish I had a raised hearth, but that is not the case so on to RRRRRs I go.

 

[nlittle]

I have a sheet of micore ceramic board that I didn't use if you are interested in buying it.....

It's the only thin material, apart from air gaps that has decent r-value and is non-combustible. 1/2" is an r-value of 1.

Thanks, but I found a place in Londonderry (very close) where I can get a sheet of Micore 300 (1/2" 4x8) for $38.
If anyone else is looking near the Rockingham County/ Merrimack Valley check this place out: http://www.kamcoboston.com/Locations/default.asp