Question about air space between wall and durock

Clearances are always to the original combustible wall....so at least that is one question answered.
Example: 36" with no protection, cut by 66% with some protection types = 12" from rear of stove to original sheetrock (or maybe 11" to the durock.

You do have to remind us on the stove model - was it an old "generic" stove like a fisher, etc.

There are probably ways to address the outlet issue, but we should see the stove or area.....

I am a newbie to this forum but have read enough already to see I am in the right place for some qualified answers finally. Have looked high and low for installation specifics other than what came with my stove which is a Century FW300010.

I have an alcove install that is built like a bay window with three outside walls. It is 33" deep with the longest outside wall width at 56". The total opening size is 78" across the face into the living room. There is a header at 88" high within the original wall creating the 88" ceiling height within the alcove. I can post a picture of the installation sight if these dimensions do not make sense.

Because the side walls are on angles I have not been able to find any information for set backs that applies. I have covered the wood studded walls with 5/8" drywall and am trying to figure out if I need to now line the entire alcove with Durock or only portions of it? The information I found shows to strip the studs with two 1/2" strips of Durock and then attach complete sheets over these creating a dead airspace. As I understand this allows a stove to be placed up to 2/3rds of the manufactures recommended distance from combustible walls. I am also wanting to install tile or some decorative covering over he Durock. If I must line the entire alcove it could get kind of pricey before I get this thing set.

I am unclear if I should place Durock on the ceiling of the alcove. Can I just nail Durock right onto the sheetrock around the back and sides of the alcove up to a level above the actual stove or do I need to do this dead air space?

After reading some of the other threads it also looks like I may not have enough triple wall chimney pipe. I only have about 10' from the ceiling up?

I apologize for so many questions at once but thought I would get the significant ones out there and see what information comes back.

Any assistance would be appreciated as I am frustrated with the lack of support I have found with the manufacture, the local fireplace shops and Lowes who sold these stoves.

Thanks
Ed

CWYfire said:

I am a newbie to this forum but have read enough already to see I am in the right place for some qualified answers finally. Have looked high and low for installation specifics other than what came with my stove which is a Century FW300010.

I have an alcove install that is built like a bay window with three outside walls. It is 33" deep with the longest outside wall width at 56". The total opening size is 78" across the face into the living room. There is a header at 88" high within the original wall creating the 88" ceiling height within the alcove. I can post a picture of the installation sight if these dimensions do not make sense.

Because the side walls are on angles I have not been able to find any information for set backs that applies. I have covered the wood studded walls with 5/8" drywall and am trying to figure out if I need to now line the entire alcove with Durock or only portions of it? The information I found shows to strip the studs with two 1/2" strips of Durock and then attach complete sheets over these creating a dead airspace. As I understand this allows a stove to be placed up to 2/3rds of the manufactures recommended distance from combustible walls. I am also wanting to install tile or some decorative covering over he Durock. If I must line the entire alcove it could get kind of pricey before I get this thing set.

I am unclear if I should place Durock on the ceiling of the alcove. Can I just nail Durock right onto the sheetrock around the back and sides of the alcove up to a level above the actual stove or do I need to do this dead air space?

After reading some of the other threads it also looks like I may not have enough triple wall chimney pipe. I only have about 10' from the ceiling up?

I apologize for so many questions at once but thought I would get the significant ones out there and see what information comes back.

Any assistance would be appreciated as I am frustrated with the lack of support I have found with the manufacture, the local fireplace shops and Lowes who sold these stoves.

Thanks
Ed

Click to expand...

don't understand but.... i measure my clearances based on the closet part of the stove to the wall .....thats where i start..

based on ur specs u shouldn't need to do much

I don't have the actual dimensions of your stove, but I have the CFM Corp. clearance sheet, and I think I understand your alcove layout. The clearance sheet doesn't specifically address an alcove installation, so it's up to you and whoever's gonna approve what you do to come up with a reasonable plan based on the guidance you have from the manufacturer. You say the alcove's 88" high inside, CFM says you need 54" above the stovetop to the ceiling. So, provided the upper surface of the step-top on the stove is not more than 34" above the floor, you're OK there. CFM says the rear heat shield can be as close as 15" from the back wall...but be careful with that one, because if you're using single-wall stovepipe, you have to maintain 18" from the pipe to the wall. What gets tricky is the sidewalls. Since I don't know how wide your stove is, I can't say how far you can push it into the converging walls of your alcove before you reach a constraint on either the sidewall clearance ("A" = 26"), or the corner clearance ("C" = 12"). I don't want to sound like a spoilsport, but I don't think you're gonna find it'll go in there very far. I suggest you draw a scaled diagram of your alcove, make a little scaled cutout of your stove, and slide it in there and see what you can come up with while maintaining compliance with all the CFM clearance requirements. On the questions about wall shielding, since the CFM clearance sheet makes no mention of reducing the stated clearances through the use of shielding, that would be a hard sell. In any case, putting up Durock, or any other sort of shielding material without a 1" ventilated airspace is just a waste of time and money and perfectly good Durock. Rick

Thanks for your speedy reply's. I think I should be OK on the height of my alcove above the stove. But please let me know if you disagree.

The stove dimensions are 29 1/2" H 23" W 22 1/2" D. The width of the actual stove is less than the top plate which hangs over 3 1/4" so it is 26 1/2" Wide. The depth is not counting the ash tray under the door and is measured from the front door to the outside of the heatshield on the back.

The backside of the 6" flue pipe opening is 2 1/2" forward from the back of the heat shield and is 10" from each side of the 26" top plate.

The angles of the alcove is part of what is troubling me. I built it to sit the stove at the 12" mark from the back wall planning another 1 1/2" closer with the 1" air space and Durock. The back corners are far enough away if it were a corner install but are not far enough from the manufacture's side wall installation sitting parallel to the corner. My problem is that the sides are not at the 26" clearance until the angle reaches a distance of 17" from the back of the stove, which is about two thirds of the depth. This is also sheetrock measurements I am giving you on the angle sidewalls. If I am to put the Durock airspace then this diminishes another 1 1/2" or so.

Am I incorrect thinking that with the Durock specs using a 1" airspace I can diminish the manufacture's side and back wall requirements by 2/3 of the distance? I don't want to burn the house down.... lol

The information on Durock being a waste if not installed with an air space is good information. I have never built a fire wall like this before. As I understand on top of the 5/8" sheetrock I need to strip it with 4" strips of Durock on 16" centers leaving a one inch air space. Does that sound correct?

Should I pull a coat of sheetrock mud over the paper on all of the sheetrock and then paint it to have a seal over the paper?

Am I reading the Durock instructions correct to leave a one to three inche space on the walls near the floor and at the ceiling about the same so there can be circulation. Could someone elaborate more on these actual measurements and how to do this correctly? I am also planning to cover the Durock with something. What would be best to use, ie tile, marble, thin rock, etc.?

I am unsure if I need to Durock the entire alcove including the ceiling or just the lower wall area around the stove and up the back wall where the single wall pipe will radiate? If I need to Durock the Ceiling do I also use the 1" air space type installation?

Thanks in advance for any and all your help,
Ed

Also could someone describe how to install Durock correctly on a wood subfloor? Do I need to pull a coat of something like thin coat prior to screwing down the Durock to the 3'4" plywood subfloor? Again I am planning to cover the Durock and any suggestions on what to use would also be appreciated.
Thanks
Ed