Durock Next Gen - Hearth?
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Micore is pretty soft. You'd want it covered. I put down a quarter inch backer board and then thinset/tiles. That hearth is still in use at a rental.
Nice. Hmm, the backer board goes over the micore, gotcha. Since I have enough durock purchased already to get my R-value, I'll probably just use that, unless micore has better fire-safety properties compared to durock. Good to know though, good for future forum-readers, thanks =)
For what it's worth the the company lists the Rvalue as what sweeps' website says
Thermal "R"/k value C518 0.49/1.27 0.39/1.27
found here: https://www.usg.com/content/dam/USG...ck-next-gen-cement-board-datasheet-en-can.pdf
on page four in "thermal"
Thermal "R"/k value C518 0.49/1.27 0.39/1.27
found here: https://www.usg.com/content/dam/USG...ck-next-gen-cement-board-datasheet-en-can.pdf
on page four in "thermal"
BillGriggs
New Member
Sorry to bump this rather old thread, but 1/4" durock over micore is what I'm planning on before tiling. Has this held up well EatenByLimestone? I see 1/2" recommended everywhere but am trying to keep the tile as low as I can.
Yes, it's held up. I had a few tiles come list, but that's more related to my tile job than the materials.
WoodyIsGoody
Minister of Fire
If you let the renters use a wood-burning appliance, they WILL split wood and kindling on your tile hearth.
Bill, as long as it's just foot traffic, I think the 1/4" will be fine if it's bedded in thinset. If there is a piano in the room (or the refrigerator might be dollied over it), I don't think even 1/2" Durock is going to save you. And that Flexbond is worlds better than anything used even 50 years ago (in terms of bond strength and ability to absorb small amounts of flex). Make sure you get good coverage when your setting the tile. Avoid leaving voids by back buttering your tiles.
WoodyIsGoody
Minister of Fire
I've squeezed it between my thumb and forefinger, I don't recall stepping on it. Bill is planning on using the 300 which is considerably harder. Maybe you're thinking of the 160? Once that Durock is sandwiched in there with thinset on both sides and a layer of tile on top, it would take something really, really heavy in a very small area to cause enough flex to make the tile/grout fail because the load will be distributed over a rather large area and the amount of compression will be very small, even by tile standards.
BillGriggs
New Member
Yes, the piece I have seems maybe a little bit softer than particleboard but about equivalent. Once there's some durock and thinset in the mix I'm hoping it will be fine. It's not a huge hearth, and is in such a spot that it probably won't ever see foot traffic.
My original hearth was simply tiles glued to millboard that had been nailed down, and the tiles were fairly thin. Only one of them had cracked (which looked like it was from a physical blow of some sort. I'm hoping studier tiles, along with the addition of durock and the two layers of thinset will make it much more solid.
WoodyIsGoody
Minister of Fire
Good thinset coverage on the back of the tile remedies that problem. The industry standard is 80% coverage with no voids at the tile perimeters. Properly set tile has incredible compressive strength, enough to drop splits 6 feet with no damage. But don't do that on a hearth with a sandwich of Micore in there.
WoodyIsGoody
Minister of Fire
BillGriggs
New Member
We're planning on just using a transition piece from the tile to the laminate flooring. The micore is sitting at the level of the particleboard underlayment and will likely end up 1/2" or so under the laminate.
I've been searching for updated info on the Next Gen Durock as a heat shield and thought I'd add what I found today to this thread.
I called USG and they said not to use it, but I'm going to anyway because the reason not to is that the board will "break down over time". I asked for clarification about what this meant - it will crack and might "disintegrate" with continued exposure to heat over 200 degrees F. Since I am tiling it, I'm going to take my chances. The board will not ignite, it doesn't transfer any more heat. The issue is not one of fire safety, but of longevity of the product.
I called USG and they said not to use it, but I'm going to anyway because the reason not to is that the board will "break down over time". I asked for clarification about what this meant - it will crack and might "disintegrate" with continued exposure to heat over 200 degrees F. Since I am tiling it, I'm going to take my chances. The board will not ignite, it doesn't transfer any more heat. The issue is not one of fire safety, but of longevity of the product.
In researching Durock, I came across a submittal form at <http://literature.puertoricosupplier.com/036/PW35766.pdf>. It shows how Durock can reduce minimum clearances. It states at the top "Cement-board wall shields and floor protectors for UL-listed solid-fuel room heaters and stoves" and toward the end, "Standards Durock cement board is listed by Underwriters Laboratories, Inc., for use with UL-listed solid-fuel rooms heaters and fireplace stoves.
So If the wood burner is UL listed...
So If the wood burner is UL listed...
It's always good to check. Currently Durock Nex-Gen is listing perlite as the lightening ingredient. Perlite is a volcanic product and non-combustible.
Re tile breaks
I have had 6x6 tile over durock and micron for about 5years. I drop the occasional split, so far no breaks.
Could be just lucky, but I thought I'd share my experience
Here is the old note on the install:
First step was to widen the hearth. I went with a tile pad ~ 69x69 inches flush to the floor. To get the space I needed for the proper insulation, I took off the sub floor, sistered the joists with 2x4s, ¾ in down, and laid ¾ in plywood into the gap. On top of this I laid a sheet of aluminum flashing to even out any heat that made it through the insulating layers ( ½ in of micron 300, R~1, and ½ in of Duroc Next gen, R~0.4) . Next was ¼ in tile for a non combustible surface ( the mortar took up the other ¼ in) . The tile guy laid in ¼ in mesh hardware cloth in the mortar to give it additional tensile strength (not sure if it is necessary, but he was the craftsman, and he wanted it) . The manual calls for R ~0.8, so the R~1.4 is overkill
I have had 6x6 tile over durock and micron for about 5years. I drop the occasional split, so far no breaks.
Could be just lucky, but I thought I'd share my experience
Here is the old note on the install:
First step was to widen the hearth. I went with a tile pad ~ 69x69 inches flush to the floor. To get the space I needed for the proper insulation, I took off the sub floor, sistered the joists with 2x4s, ¾ in down, and laid ¾ in plywood into the gap. On top of this I laid a sheet of aluminum flashing to even out any heat that made it through the insulating layers ( ½ in of micron 300, R~1, and ½ in of Duroc Next gen, R~0.4) . Next was ¼ in tile for a non combustible surface ( the mortar took up the other ¼ in) . The tile guy laid in ¼ in mesh hardware cloth in the mortar to give it additional tensile strength (not sure if it is necessary, but he was the craftsman, and he wanted it) . The manual calls for R ~0.8, so the R~1.4 is overkill
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