1st post - Hearth Pad construction

[nygiants0180]

I just bought a Encore Non-Cat Wood stove and I wanted to make my own hearth. Right now the floor is just a plywood sub-floor. Is it possible to just use a layer of 1/2" Micore 300 or 160 Mineral Fiber Board (or similar board) with 1/4" tile on top of that? I would love to have the hearth be flush with the 3/4" oak flooring I plan to put down for the rest of the room. The R-value for the bottom of the stove is .59. Also is the Micore board strong enough to hold the 400lb stove?
Thanks some much in advance for any advice

 

[CarbonNeutral]

Micore is not strong enough - you want to add a layer of cement board between the tile and mineral board - NOTE: cement board, the heavy stuff, not the lighter hardibacker stuff that has combustible filler in it.

 

[edthedawg]

+1

Get Durock (NOT DUROCK-NEXT) and might even be better w/ 2 layers of the 1/2" stuff there. Plus solid "pads" of it right where the stove feet rest, for even better support.

 

[John_M]

I would speculate that if you place a 400# stove on top of grouted 1/4" floor tile on top of 1/2" Durock and 3/4" plywood sub-floor you will notice significant cracking in the grout seams within one week after installation.

My 350 # stove sits on 1/4" floor tile set in latex modified mortar. That sits on top of 1/2" Durock set in latex modified mortar. That sits on top of two layers of 3/4" plywood set perpindicular to each other and each layer is screwed separately to 2x6's, placed 12" on center (O.C.). The layers of plywood are glued together and each layer is screwed 6"O.C. at the edges and 8" O.C. in the field. The Durock is set using approved Durock screws following their recommended pattern.

The tile grout was dried according to the instructions and misted with a spray bottle for 48 hours during the curing process.

It took three guys averaging about 190# each to install the stove and stove pipe. So that was about 900# on top of the hearth during installaltion.

My hearth has a few very fine hairline cracks in some of the grout seams around the stove. Didn't think that would happen.

Go Giants!

John_M

 

[Slow1]

I'm a little unclear about your 1/4" tile - is that the thickness or the widthxlength?

I used 12" square tiles on top of 1/2" Durock on top of 3/4" ply sitting on top of a 2x4 frame that is about 12" OC. I just screwed the ply down with deck screws, then the durock into the plywood along seams and randomly so it wouldn't move (I didn't know there was a recommended pattern). From there I put the tile on and then grouted per instructions on the grout box - no misting etc. Was a couple weeks before I was able to get the stove moved onto there - used a dolly to get it up there in the crate (rolled it across the pad), then lifted it to pull the crate out from under it. My 500 lb stove sits on this and I have not noticed any cracks in the grout seams. Guess I was lucky?

Now - my stove doesn't require anything beyond ember protection so I didn't have to get up to your R-value. Having burned the Encore NC last year, I would take that R-Value seriously - it will get hot under that stove, particularly in the back. I would suggest that if anything you exceed the recommended R-value and be sure your clearances in the back exceed the recommended minimums as that puppy WILL run hot in the back in normal operations, if you experience any of the common problems it will get even hotter... best to be prepared for that.

 

[nygiants0180]

Thanks guys for all the info... I will adjust my plans accordingly!

 

[CarbonNeutral]

I'm a little unclear about your 1/4" tile - is that the thickness or the widthxlength?

I used 12" square tiles on top of 1/2" Durock on top of 3/4" ply sitting on top of a 2x4 frame that is about 12" OC. I just screwed the ply down with deck screws, then the durock into the plywood along seams and randomly so it wouldn't move (I didn't know there was a recommended pattern). From there I put the tile on and then grouted per instructions on the grout box - no misting etc. Was a couple weeks before I was able to get the stove moved onto there - used a dolly to get it up there in the crate (rolled it across the pad), then lifted it to pull the crate out from under it. My 500 lb stove sits on this and I have not noticed any cracks in the grout seams. Guess I was lucky?

Now - my stove doesn't require anything beyond ember protection so I didn't have to get up to your R-value. Having burned the Encore NC last year, I would take that R-Value seriously - it will get hot under that stove, particularly in the back. I would suggest that if anything you exceed the recommended R-value and be sure your clearances in the back exceed the recommended minimums as that puppy WILL run hot in the back in normal operations, if you experience any of the common problems it will get even hotter... best to be prepared for that.

With just 1/2" micore you're over one already, which is great considering Slow1's comments

 

[John_M]

Slow1, In my case the 1/4" tile is the thickness of the tile (it appears to be closer to 5/16" thick but it is called 1/4"). The dimensions of the tile I used are approximately 13" wide x 13" long.

I was surprised and disappointed by the appearance of the hairline cracks because I thought I had overbuilt the hearth. Same old story: "I can guarantee the effort but I cannot guarantee the results."

Best wishes to you and all.

John_M

 

[Slow1]

Slow1, In my case the 1/4" tile is the thickness of the tile (it appears to be closer to 5/16" thick but it is called 1/4"). The dimensions of the tile I used are approximately 13" wide x 13" long.

I was surprised and disappointed by the appearance of the hairline cracks because I thought I had overbuilt the hearth. Same old story: "I can guarantee the effort but I cannot guarantee the results."

Best wishes to you and all.

John_M

Well, you got me to go back and look for them - I don't see anything (yet?). Guess it is better to be lucky than right sometimes? Sorry that things turned out that way, but on the bright side I bet you are probably the only one who notices those cracks - not that it helps you any really. I see every flaw in my pad like it were highlighted with dayglow paint (and believe me, there are plenty!). Such is life, but I guess it gives these projects some character.