Hearth And Surround Questions

[fdegree]

Please correct anything I am about to say here...I think I have a grasp of what is needed for the hearth, but I would like some confirmation from the experts.

I will highlight my questions to make them easier to follow.


Hearth:
I am planning to purchase, either a Blaze King King or Lopi Liberty, over the summer (most likely the King). As far as I can determine, by reading their respective owners manuals, neither has a required R-value for the hearth...simply spark protection. So, I believe I can build the raised hearth frame out of 2x6's, then cover the wood frame with 3/4" plywood, cover that with a cement board of some kind, and cover the cement board with ceramic tile to finish it. This will raise the hearth to approximately 8" or so. If I am incorrect with any of this, please let me know.

I will certainly have to remove the carpet from this area, but should I remove the sub-floor as well? If so, this would open up the raised hearth cavity to the crawl space.

Will this construction be sufficient for a future replacement of the stove in 30 years? Again, correct me if I am wrong, but it seems more and more stove manufacturers are requiring less and less R-values from the hearth. So, in the distant future, is it safe to assume that most will only require spark protection...making this construction adequate for any future stove I may get. I realize no one can predict the future, but does this sound like a safe bet? I'm simply trying to plan ahead.

Surround:
I would like to cover the wall, behind the stove, for aesthetic reasons. I do plan to have the rear shield installed on the stove so I can reduce the clearance requirements to the rear wall.
What kind of wall prep will I need? i.e. - remove dry-wall, affix cement board to dry-wall, air cavity between dry-wall and cement board...



Thank you, in advance, for your guidance

 

[begreen]

Building a hearth essentially is about clearance to combustibles. If concerned, eliminate the combustibles like the plywood top and perhaps the wood joists. Some stoves have rigorous needs for a well insulated hearth. Others need only ember protection. Both the Lopi and BK have modest hearth requirements and your design will work fine. For most hearths there is absolutely no need to remove the sub-flooring.

I can't predict what will be happening in 30 years, except that if I last that long there's a good chance that I will be suited up with Depends and eating mush. :shut: Ugh. Don't worry about it unless you are an engineer, in which case you need to eliminate the plywood and the wooden 2x6's and go all metal and cement board. But for the stoves listed if you want another layer of protection, I would just add a layer of sheetmetal under the cement board and call it done.

The wall surround is more an issue of the materials chosen unless the intent it to build an NFPA wall shield. As a general guideline, don't scrimp on clearances. The manufacturer's specs are the minimums. I like to exceed them wherever possible.

 

[fdegree]

Thanks...I appreciate the input

 

[lukem]

Since this is essentially new hearth construction and the cost difference for materials is negligible, I would build for something that does require some R-value protection. Who knows...that BK/Lopi might not be what you want a few years down the road. At least your hearth will be able to handle whatever you want in the future.

My .02

 

[azsteven]

In our town, a stove install requires a permit and inspection. It never hurts to take a drawing in and talk it over with the building inspector beforehand. When we were planning the install, the building inspector was thrilled that I took a picture and the stove's manual in to ask him what he would recommend. Turns out he runs a pellet stove himself, and was a bit of an enthusiast. More importantly, he explained what he was going to look for to be sure everything was up to code. Why guess when he'll tell you up front and then you know what to build. He came out the same day that the installers were there, and was really pleasant to work with.

 

[fdegree]

Thanks for the replies. I am certainly considering the additional r-value build just in case the future might require it.

As for the inspector...not to worry. Since I am not in town there is no need for a permit nor an inspection. But, I appreciate the advice anyway...all opinions are valuable to me at this stage.

 

[KB007]

Sincw clearances vry by manufacturer and model, I'd suggest you do a bit of surfing for some manuals of similar sized stoves to what you're planning on putting in and b uild to the worst case scenario and add some for the hellovit. That way, on the off chance you change out later to a different stove you will have more chance of being OK than if you just build to what you're installing now.

+1 on the metal heat shield - according to our inspectors around here, once you have a heat shield, youcan put down pretty much anything that is non combustible.

 

[fdegree]

I would just add a layer of sheetmetal under the cement board and call it done.

+1 on the metal heat shield

Anyone know what the r-value of sheet metal is? I searched a few different sites that listed the r-value of various materials, but none had sheet metal listed.

 

[KB007]

It's not because of any R-value, it's because it reflects the heat back and is considered like a "fire barrier" or something along those lines - I don't recall the exact term that's used.

 

[Wood Heat Stoves]

It's not because of any R-value, it's because it reflects the heat back and is considered like a "fire barrier" or something along those lines - I don't recall the exact term that's used.

sheet metal w/o air space behind isn't considered a shield per nfpa

to the op, 1/8" horizontal still air adds .92 r value, and 1/2" durarock/wonderboard adds .2r, 1/4" tile adds .01r, 1" of cement mortor adds .2r
for example

 

[fdegree]

Thanks for the information...it is truly appreciated