Help. Can't for the life of me make sense of what I can or need to use to make a hearth pad for a woodstove I'm installing. The unit states it needs 3/8" millboard, which I gather isn't made any more, or a k factor of .84 btu in/ft2(squared) hr. I can get durock or hardibacker 1/4" or 1/2" and 1/4" ceramic tile for the top. Suggestions? one layer of 1/2" durock or hardibacker then the tile on top? two layers of 1/2" durock or hardibacker then the tile? Do I need an air space?
newbie hearth pad q's
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It is a Kent woodstove I got from a friend. It was in their lake house and has had maybe a dozen fires in it. Pristine condition but no manual. It does have the spec plate on the back with the clearances and the formula I posted above as what is needed for the pad. It calls for an .84 btu in/ft2 hr floor protector.
and that is the k factor. looking at this table:
https://www.hearth.com/econtent/index.php/articles/k_values_what_does_it_all_mean
it looks like to get a k factor of .84 with durock I would need 2.3 inches or five 1/2" layers of it?
https://www.hearth.com/econtent/index.php/articles/k_values_what_does_it_all_mean
it looks like to get a k factor of .84 with durock I would need 2.3 inches or five 1/2" layers of it?
5 layers isn't the end of the world but does sound like kinda a pain in the ass to keep layering. You're likely talking about 10 sheets or more there, depending on how big you need to go, how you break up seams, etc. If your floor system isn't going to complain about the weight, it would work, but you may want to think about doing something thinner/lighter. Find some micore, or call a real building supply co (hint: NOT Lowes/Depot) and find mineral insulation board, or design yourself something w/ steel studs.
A driving question may be how big the footprint of your hearth needs to be? Have you examined all the clearances to combustibles behind/around the stove? the stove measurements? the clearance needed in front for embers? that can be a lot of square footage, getting far enough away from the walls/trim and still leaving at least 18" (hint #2: go bigger when you can!) in front of the loading door(s).
Good luck, don't hesitate to keep asking questions
A driving question may be how big the footprint of your hearth needs to be? Have you examined all the clearances to combustibles behind/around the stove? the stove measurements? the clearance needed in front for embers? that can be a lot of square footage, getting far enough away from the walls/trim and still leaving at least 18" (hint #2: go bigger when you can!) in front of the loading door(s).
Good luck, don't hesitate to keep asking questions
so does that mean I read the table right? if so it sounds like I need to find a local dealer for some micore 300. it costs more per sheet but I would use less.
you'd use substantially less. still need the Durock over top of it for stability - can't tile directly to a mineral board product like Micore, typically. You should talk to the building supply co guys tho - see if they have a hearth-ready material which is rated and can be tiled over. traditionally folks here tile to the Durock, and the real insulation happens below that Durock, whether it's Micore or airspace or something else.
In short answer, yeah - you appear to be reading the table right.
Have you thought of not only the sq ftage of the hearth (i.e. my prior post) but also how tall a hearth you would like? think about how you'll finish the front edge - just something to think about.
In short answer, yeah - you appear to be reading the table right.
Have you thought of not only the sq ftage of the hearth (i.e. my prior post) but also how tall a hearth you would like? think about how you'll finish the front edge - just something to think about.
absolutely, I really don't mind it being very thin. If I can get some micore I could make it with a plywood base, then micore 300, then a 1/4" durock or hardibacker for the tile base, then tile, and edge it in wood. question then becomes how to fasten all those layers together without creating a heatsink all the way through them with nails or screws.
still going to be pretty heavy.... but it isn't like I'll ever be moving it.
still going to be pretty heavy.... but it isn't like I'll ever be moving it.
A few simple searches on this site, using words/phrases like "hearth", or "building a hearth", or whatever, would yield a wealth of information from folks who've been down this road before. Just a thought to keep you from inventing yet another wheel. Rick
trust me, I'm a lazy sod, I'll use the experience of everyone else to save me some effort. appreciate your replies.
Nails/screws thru the sandwiched layers aren't a problem. You're overthinking it. relax and plan something simple.
And um, what Rick said.
(why do i feel like i just wrote that earlier today??)
relax and plan something simple. And um, what Rick said.
(why do i feel like i just wrote that earlier today??)
ok, I'll slow down on that. seems next step is to go get my permit from the county so I'm certain of what they will want, and wait for a reply on two dealers the micore site had close to me. found some nice tile in the clearance pile at home depot today, need to go back and get a box tomorrow. need to drop a plumb bob from the ceiling to the stove so I can drill a pilot hole and get in the attic space and check clearances before I start building the pad. not a hard job, but one that certainly has plenty of small steps to do correctly...
jumby181 said:
bingo.
take/post pix w/ q's and it'll help a lot when you get down to little specifics.
Inspector will want to see a manual for the stove, then come out and inspect the final installation to ensure it's all done proper.
Talk to your insurance co too - see if they have any special requirements.
OMG.... apparently in the state of VA micore is unheard of, except at one company that can only get it in pallet loads of 80. Anyone in VA know of a source for it?
micore 300 located at atlantic plywood in richmond, va. $40.80 for a 3/4 4'x8' sheet. Which I do believe is enough to cover my r value. so the question is, a sheet of 1/2" plywood, the micore 300, then a cement board to lay tile on. how much backer board should I be putting down to provide a stable base and take the weight of the stove? 1/2" enough?
I couldn't get Micore when I built the hearth pad for my 30.
I used metal framing studs (doubled up into a "box" for strength) to give me an air gap. Three layers of Durock was screwed down over that, and then 1/4" ceramic tile on top of that.
-SF
I used metal framing studs (doubled up into a "box" for strength) to give me an air gap. Three layers of Durock was screwed down over that, and then 1/4" ceramic tile on top of that.
-SF
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