finishing a stove install ...wall & hearth, need help

[fishboat]

I'll be doing the finish work after an install of a Bis Tradition CE.

What non-combustable material is best to use for the area surrounding the unit & what material would be best for the hearth surface just in front of the stove?

The hearth surface will be slate tile. The wall around the unit & all the way to the ceiling will be a stack-stone slate.

The Tile Shop that the slate comes from uses "Permabase" as the non-combustable material. I looked on the Unifix website & it says Permabase shouldn't be exposed to temps greater than 220F...this leaves it out for the hearth, but can it be used on the vertical surfaces around the unit?

For the hearth do I use Durock? Hardibacker? over metal studs.

Also...is there such a thing as a non-combustable adhesive or is thinset "it"?

 

[babalu87]

https://www.hearth.com/talk/threads/11196/

 

[Gooserider]

I'll be doing the finish work after an install of a Bis Tradition CE.

What non-combustable material is best to use for the area surrounding the unit & what material would be best for the hearth surface just in front of the stove?

The hearth surface will be slate tile. The wall around the unit & all the way to the ceiling will be a stack-stone slate.

The Tile Shop that the slate comes from uses "Permabase" as the non-combustable material. I looked on the Unifix website & it says Permabase shouldn't be exposed to temps greater than 220F...this leaves it out for the hearth, but can it be used on the vertical surfaces around the unit?

For the hearth do I use Durock? Hardibacker? over metal studs.

Also...is there such a thing as a non-combustable adhesive or is thinset "it"?

Permabase should NOT be used for the hearth, and I'd be nervous using it anywhere near a stove. Durock is listed for use on the hearth, and AFAIK is the ONLY cement board that is. Hardibacker tech support says NO for the hearth, but OK for NFPA walls.

According to the Durock documentation, the reccomended adhesive is a "Mortar meeting ANSI spec. 118.4 or 118.1" Their tech support people said this translates to "Latex Fortified" or "Latex Modified" thinset - Apparently both Flexbond and Versabond brands meet this, probably others, although as far as I know the only ones that do are the powder mixes, not the premix in a tub stuff. I used Flexbond on my hearth extension, it seems to work well...

If going over metal studs, I would go for at least two layers of Durock, preferably three, with the layers glued together with thinset and screws. Put the studs on 8" centers - Durock is not really intended to be used in this sort of unsupported construction, but there doesn't seem to be a non-combustible plywood underlayment equivalent, so we attempt to get the required stiffness by using extra support and more layers. The air space and Durock combo will probably meet most R-value requirements, but if you want to go for low effort/cost overkill, you can put some unfaced fiberglass bats between the studs to fill the airspace.

I also think it is good practice, although not required, to stick a layer of sheet metal (26 g or thicker steel, or aluminum flashing) in between two of the Durock layers to disipate any hot spots.

Gooserider

 

[fishboat]

Goose,

Thanks. I need to figure out the final dimensions for the finish work this weekend to be sure the stove install-position is right, next week.

I'm not sure if you'll have answers to the following, but I'll ask..

1) I tried to find the info on the Durock site, but no luck so far(slow dialup)....does Durock come in 1/4 inch thickness? I assume it does come in 1/2 inch.

2) Does Durock have a tapered edge for taping? (it's probably better if it didn't)

3) I plan on building a six-foot wide 2x4 (perhaps 2x6) false wall around the burner(Bis Tradition CE) & up to the vaulted ceiling. On one side of the hearth the ceiling is about 11 feet up. On the other side the ceiling is 14 feet up. I'm thinking of putting Durock over the entire false-wall surface up to the ceiling as I need a good surface to tile against. The "tile" is actually 4 x 16 inch blocks of dry-stacked slate that's about 1-1.5 inches thick. When all the tile is in place I'll have around 1000 pounds of "rock" thinset-ed to the Durock. Now the question...any idea whether Durock is appropriate for such a vertical & heavy tile install? If not...do you know of any way to find out? Call Durock I suppose?

3) In case I can't find Durock around here...what is Wonderboard? Same thing? (..probably not.)

4) While I've built many things over the years I haven't done anything like this. Do you have any suggestions on the best way to tie the false wall to the existing, drywalled, finished wall above the mantle & up to the ceiling? The existing wall is a 2x4 load bearing wall between the great room & the garage. The false wall will just be a bump-out added onto the existing wall.


The 8 inch-on center spacing for the hearth sounds like a good idea. The flashing will also be done. I plan in filling the under-hearth open space with some 6# density rockwool I have left over from another project.

thanks...

 

[DriftWood]

1 Durock spec. (broken link removed to http://www.usg.com/USG_Marketing_Content/usg.com/web_files/Documents/Prod_Data_and_Submittal_Sheets/DrckCement_Board-Submittal_Sheet_CB399.pdf)

2 tapered edge for taping does not matter filled with thinset and tape.

3a ? John Bridge forum ask them - Tile your World
http://www.johnbridge.com/vbulletin/index.php

3b what is Wonderboard? Same thing just a different brand
http://www.jamoinc.com/documents/ds_english/Surface Preparation/1-2 WonderBoard DS.pdf

4 I set up a wall made of steel framing members tap coned into the old fireplace brick. nothing as big as yours.

 

[Gooserider]

<much trimmed - Driftwood answered alot of the questions as well as I would have...>

2) Does Durock have a tapered edge for taping? (it's probably better if it didn't)

No, it doesn't really need one as the minimal lump from taping is going to be covered by the thinset and tile you are putting over it.

3) I plan on building a six-foot wide 2x4 (perhaps 2x6) false wall around the burner(Bis Tradition CE) & up to the vaulted ceiling. On one side of the hearth the ceiling is about 11 feet up. On the other side the ceiling is 14 feet up. I'm thinking of putting Durock over the entire false-wall surface up to the ceiling as I need a good surface to tile against. The "tile" is actually 4 x 16 inch blocks of dry-stacked slate that's about 1-1.5 inches thick. When all the tile is in place I'll have around 1000 pounds of "rock" thinset-ed to the Durock. Now the question...any idea whether Durock is appropriate for such a vertical & heavy tile install? If not...do you know of any way to find out? Call Durock I suppose?

I think Durock is not the right solution for that thick a material, neither is thinset as I understand it. The "Tile your World" site that DW pointed you at should be able to give a better answer, but I believe the requirements include some extra reinforcing mesh, tie straps, etc. When you are getting into that much thickness, you are almost looking more at masonry than tiles...

3) In case I can't find Durock around here...what is Wonderboard? Same thing? (..probably not.)

Wonderboard, and Hardiebacker are competing versions of cement board. Both would be fine for your walls, neither is listed by the manufacturer for the hearth floor itself. You may also encounter a cement boad called "Permabase" that is NOT appropriate for use close to the fireplace as it shouldn't be exposed to temps over 220*F (it has styrofoam beads in it's composition)

4) While I've built many things over the years I haven't done anything like this. Do you have any suggestions on the best way to tie the false wall to the existing, drywalled, finished wall above the mantle & up to the ceiling? The existing wall is a 2x4 load bearing wall between the great room & the garage. The false wall will just be a bump-out added onto the existing wall.

Not really, I'm not a builder, though I can drive nails through television sets... :lol: That question is WAY out of my league, but there are several other folks on the board that probably could answer it without even thinking hard - Elk, Keyman and Hogwildz come to mind right off the bat, probably lots of others as well. Hopefully one of them will chime in, if not you might start a thread about it over in the "DIY room" as wall building is hearth related in this case, but is starting to get a little far afield.

The 8 inch-on center spacing for the hearth sounds like a good idea. The flashing will also be done. I plan in filling the under-hearth open space with some 6# density rockwool I have left over from another project.

thanks...

The rockwool would be even better, I just suggest the glass as it works just as well in that application and is cheaper / easier to come by for most folks. Of course using up suitable stuff you already have on hand is better yet.

Gooserider