Hearth build?

[alwaysfixin]

I've been searching forums & different sites for quite some time (project kept getting delayed but now necessary complete asap) and instead of solid answer seem come up with more questions.

I have a wood cook stove exempt EPA. It is a Cabin Tender by Amish builder Ashland Stove. I've not received answer from exclusive dealer to my question. Only way to contact builder is by mail. Not clear what really required for floor protection/insulation for the stove. Want to follow code but just not clear to me what actually needed.

The stove manual provided with stove is for the Ashland Stove which is larger & actually closer to floor. For that stove it gives the following as protection requirements for floor (It does specify spacing rear, sides & front that match code).

"3/8 millboard, metal covered board or equivalent protector board". (Note: they next mentioned aluminum diamond plate (ADP) that they manufacture as acceptable)

I've found lots different specs for millboard so adds to confusion trying figure out equivalent protector. However, if the ADP is indicator seems insulation needs not significant.

The stove bottom itself sits up 10 1/4" above floor on four legs. It has an ashpan floor that has 2" air space between floor & bottom of stove. The firebox floor is 21" from floor. I've seen references that state if above certain height above floor & ash pan that protection is very minimal (mainly ember?? which would seem supported by the ADP being acceptable).

Preference is to have something on top of the pine floor if possible as save time tweeking everything due to other issues (will have separate question on that due to ceiling joist location & needed pipe offset). Don't like regular stove board & it isn't in sizing fit my need. I'm in process of laying the flooring so trying to determine if build hearth on subfloor, on top flooring or if something thin just ontop of the floor. Floor is 3/4" pine plank, sub floor is Advantec 23/32" on 16"oc open web joists.

Just metal on top of flooring? Would tile work with durock? Any input appreciated to clear the smoke from this confused mind.

Thanks

 

[begreen]

3/8" covered millboard is standard cover all for a type 1 ember protection. A plywood base covered with cement board and tile should suffice. It should extend at least 16" in front of the firebox door.

 

[bholler]

Is this a ul listed stove?

 

[alwaysfixin]

Thanks for clarifying the 3/8 millboard. I was seeing all sorts of "specs" as to insulation value of millboard up to 1.4 so wasnt sure.

no, not ul listed. Know potential issues with insurance but not a factor in this case. Only goal is safe install.

 

[begreen]

If you want to be extra safe, put down 3/4" plywood, then two layers of 1/2" Durock NexGen cement board, then tile. Stagger the seams between the Durock layers so that they don't line up.

 

[alwaysfixin]

ok, project got delayed. The more I read the more confused getting. The mfg requirements are very simple from a piece of diamond plate directly on the floor to a metal covered board or 3/8 millboard or equivalent. Yet, it seems people are recomending much higher builds (understand that) but I'm trying to find the sweet spot & yet keep as simple & low as possible. The stove only requires ember protection. I had purchased enough 1/2" Micore 300 to do a pad when planned to floor around it (recessed) but decided to floor everything & do something less permanent. However, I really want to keep the pad as low as possible. This is a cook stove as well with warming shelf & water reservoir on the back & I'm on the shorter side of things.

Existing floor is Advantech 3/4" plus nailed down 1" pine t/g. Mfg web joists are 16" centers so plenty of strength. I would like to keep the pad removable and not really be putting screw holes into the flooring.

- begreen your earlier suggestion layer of plywood plus cmu & tile was good. Is there a problem with the cmu directly on the floor without the plywood? If absolutely necessary what is thinnest plywood necessary?

- Can Micore 300 be put directly over the existing flat/level floor?

- What amount of wood or cmu would be necessary to provide stength to support 400-450# stove on top of the micor layer? That stuff is pretty dense but I'm sure the weight concentrated in the legs could eventually compress. Yet, with 1/2 cmu plus tile would that be enough?

- As for the cmu. Hardibacker? Much has been written on the forum regarding it & containing cellulose. I like Hardibacker much better than Durock. Already have some plus for me it is just nicer to work with and it will have porcelain tiles on top. Any issues using that either without or with the Micore? Not needing R value only ember protection?

**I'm leaning toward just a layer of cement board covered with tile as it would meet the requirements. I'm wanting to finish edges with a pine trim but not seeing how would attach to cement board...any ideas?

I would even go the mfg suggested metal if could find 62" x 60-72" piece without costing a fortune. Yet already have micore so am entertaining whether to use it or sell it. From reading other posts it looks like it might make my pad quite tall

Any help/clarification would be appreciated. Ready to get this stove in so can be warm this winter.

 

[begreen]

A metal plate would be the simplest, based on the description. It seems like the complicating factor is the fellow building this.
The stove is not particularly heavy. Our stove weighs more. The point of the plywood backer is to increase rigidity which is more important if you want something freestanding and unattached to the floor. It's what the backerboard (CMU) is attached to. You could lay down the backerboard right on the flooring, but it would need to be screwed every 8". It doesn't sound like you want to do that. Hardibacker should be ok in this low heat application. The micore is just another layer, but if used it definitely needs to be sandwiched between rigid materials. By itself it is too spongy.