Hearthstone Mansfield Floor Protection - w/ PICS

[linckeil]

hello, i am building a hearth pad for my mansfield. aside from the minumum hearth pad dimensions listed in the manual, there is not much information given in terms of floor protection.

Per the manual, "the unit must be placed on a non-combustible floor protector." what i'd like to build is a hearth pad consisting of 3/4" plywood, covered with 1/2" durock cement board, covered with 1/4" ceramic tile. will this meet the requirements of the manual? (which is what the inspector will refer to)

the manual makes no mention of a K-value, but does say, "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." being i am not installing it in an alcove, i don't think this applies to me. but given the above materials i mention, what would be my R-value?

thanks.

 

[Elfin]

I think you've got this interpreted correctly. The big thing is to pay attention to your clearances in addition to the dimensions... but the construction of a hearth pad that you describe will meet the requirements stated in the manual.

That's a really heavy stove, though, and I think you should look at solid-bodied porcelain rather than ceramic tile, at least for the portion of the hearthpad the stove will be sitting directly on. Porcelain is as tough as you can get, whereas ceramic may crack and/or chip under the weight (especially at that critical moment when the stove is first lifted onto the pad).

Are you connecting the outside air kit? If so, you might need to consider a hole through the pad for this purpose. Depending on how the stove is configured.

 

[linckeil]

thanks for the reply, i am considering porcelian tile aswell, but i found a ceramic tile that is exactly what i am looking for. i will be lowering the stove nice and slowly onto the pad with my engine hoist, so once i get past that critical moment, i think i'll be ok. i think the key is having a good, level, solid foundation for the tile to lay on. properly laid, i don't think porcelian would offer much more protection from cracks over ceramic - but i'm no tile expert..... any other opinions on ceramic vs porcelian tile?

does anyone have any idea what my R-value would be?

 

[Elfin]

I'll respond again and give you a bump. Someone posted a great post recently about the R-values of various materials, so if you search the archives you might find what you are looking for.

The key is a good solid foundation, but with a stove over 500 lbs sitting on 4 tiny legs... some ceramic tile could crush under that load. I wish you luck, whatever you decide...

 

[badger1968]

I think you got lucky! I just installed a Homestead (much smaller!) and the hearth specs were MUCH stricter. I had to have an r-value of 6.6 beneath the stove. Maybe the Mansfield is different fundamentally, but I just don't get it. Anyway, according to the manual, you are OK.

 

[linckeil]

yeah, i was confused by that too.... i went to the hearthstone website and read the floor protection of other model woodstoves. i couldn't believe the requirements of the homestead! There must be some serious differences between the stoves. i would have imagined the mansfield would require more protection as it's a bigger stove with a much higher BTU rating. the equinox (hearthstone's new monster) has very limited requirements as well... go figure......

 

[jbrown56]

Hi,

The only thing I would do differently is add solid blocking where the legs will sit. This will take up any deflection in the plywood.

Jim

 

[linckeil]

So I wrote Hearthstone just to get clarification on the floor protection requirements. The hearth for a Mansfield is basically there only for ember protection. The hearth I plan on building is just what Hearthstone requires for the Mansfield.

 

[linckeil]

here are some pics of the completed hearth. i designed it so that each of the 4 legs of the stove sit dead center on a full tile. it is 2 layers of 7/16" plywood, 1/2" durock cement board, and 1/4" tile. the boarder is red oak ripped to size with a routered edge. underneath the hearth i stapled some felt i bought from walmart. this way the hearth can slide on the hardwood floors without damaging it for those final adjustments when i'm connecting the chimney. what do you think?

 

[Highbeam]

We call that stuff OSB out here in the NW. How heavy is it? I would be leery about moving it once the tile is grouted for fear of flex.

Great job on the tile layout, it will look great with the soapstone on it.

 

[dgisme]

that looks great, nice job congrats. show a pic when the stove goes in!!

 

[linckeil]

thanks for the compliments. the plan is to be 100% finished with the install by the end of october.

as for weight, i really don't know. the plywood/cement board foundation was assembled out on the deck, then brought inside and placed an old (but sturdy) patio table frame for the trim install. then it was placed on the floor and hasn't left since. it was tiled and grouted on the floor and i have no intentions of ever lifting it again. at this point, it just slides around on the felt when i need to move it. if i tried to lift it i would be fearful of the tile cracking like you mention. i think it would be ok if i had the help of a few friends and we took our time, but i wouldn't want to risk it - and there's no need.

i'll add pics as i progress with the project.

 

[jbroich]

Very clever thinking re: the felt layer on the bottom.

 

[Elfin]

Hey, that looks nice... can't wait to see the final pics! It looks to me like what you used was perhaps particle board, not plywood? not sure how the two compare strength-wise.

I like your idea of the felt to keep the pad easy to slide out if needed.

 

[linckeil]

highbeam is correct, the material is OSB (Oriented Strand Board), not plywood.
it'll hold up just like plywood in this application.

 

[linckeil]

ok, so today was the day, and my back isn't broken, so i can't complain....
all went smoothly and i can't wait to hook up the chimney and start burning!!
one of the legs needs to be shimmed .040". what material is recommended? i'm thinking aluminum...
so here are some pics.... the last is where I have to punch the hole in the roof.

 

[begreen]

Sweet, you're getting real close now. The stove looks great in it's new setting.

 

[Creek-Chub]

Excellent looking stove. I'm guessing you won't be needing that electric baseboard so much?

 

[linckeil]

thanks.. yep, i'm pretty confident those baseboard heaters will not be necesary (they are oil by the way). i'm not crazy about their appearance back there, but i'll leave them at least through this season. if i find myself never using them, they'll likely be removed.

any thoughts on a shimming material for the legs? the inspector won't even know they are there, but i'm wondering if there is a preferred material?

 

[The Dali Lima]

Looks great My Oslo has the same hearthpad specs - the manual says that it is just there for ember protection. Nice job!

 

[Highbeam]

I used a washer for my stove but would happily use a dime or other coin. Just becuase you know that you need 40 thousandths I am willing to bet that you can source a piece of metal, any type of metal, that will fit the bill nicely. In a mobile home you need to bolt down the stove but in a home the stove just sits there so the inspector shouldn't have any say in how you shim it.

Looks really nice there.

 

[Creek-Chub]

thanks.. yep, i'm pretty confident those baseboard heaters will not be necesary (they are oil by the way). i'm not crazy about their appearance back there, but i'll leave them at least through this season. if i find myself never using them, they'll likely be removed.

any thoughts on a shimming material for the legs? the inspector won't even know they are there, but i'm wondering if there is a preferred material?

Just so you didn't think I was poking fun at the appearance, I wasn't. Just commenting on how much heat you're going to see out of that stove.

 

[begreen]

any thoughts on a shimming material for the legs? the inspector won't even know they are there, but i'm wondering if there is a preferred material?

.04 = 20 ga sheet metal, but it's easier to find a scrap of 26ga. Two thicknesses of that should be close.

 

[Highbeam]

Maybe buy a cheap set of feeler gauges and cut the needed ones off, even stacking them to get your 40. Is this how you measured the required shim thickness?

 

[linckeil]

Just so you didn't think I was poking fun at the appearance, I wasn't. Just commenting on how much heat you're going to see out of that stove.

not at all....that thought never crossed my mind. i was just saying saying i wasn't crazy about the look of those heaters back there....


as for the shim, i stuck a metal ruler under the leg and it shimmed it up perfectly. I mic'd the ruler with my calipers to determine the thickness. if i can't find a shim of the same thickness, i'll end up sacrificing the ruler....