With the help of the good people here, my husband and I are ready to move forward with our wood stove. The installers are coming next week to start work. We want to get the stove (Woodstock Fireview) as close to the wall as possible and have been advised by Woodstock that one of the things we need is a 1" air space Wonderboard wall behind it, as well as the heat shield on the back of the stove. We will tile over the Wonderboard. Our concern is the wall will look odd with that air space on each of the four sides. Have any of you done your install with the air space? How did you make the wall look good at the edges? I'm going to ask Woodstock if we can install two Wonderboards instead of the one with air space but I'm not sure they will go for that. Also, if any of you have pictures that show the wall with the space, that would be so helpful. Thank you in advance for your help once again.
Question About the 1" Air Space Wall for Behind a Wood Stove
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Oldman47
Minister of Fire
Multiple layers of the wonderboard will not work. You need to establish that air gap. If you minimize the air space above and below the shield wall the air gaps will not be as obvious unless you really look at the background behind the stove. Simply putting more layers of wonderboard will gain you almost nothing in terms of allowable spacing, other then the space the wonderboard eats up.
The air space is essential to provide the insulative quality, and the only way to install an approved wall shield to reduce clearance. You can trim/close the vertical sides, but the top and bottom must be open to provide a path for natural convection of air up between the shield and the shielded wall, which is what makes the system work. The shield must not be flush against the floor along its bottom edge, the air gap has to exist there, as well as along the top edge of the shield.
Thank you for your response. I'm mostly concerned with the way the wall will look on the side, which will be the most obvious. Can you explain minimizing the air space above and below? How much can I minimize it? Does it not have to be a full inch all around? The point of using two Wonderboards was not to gain space, but to eliminate the need of the air space, but I guess that won't work.
Thank you for your post. Only having upper and lower air spaces would help, but Woodstock advised that all four sides be open, which is the problem. Maybe I'll ask again and see if I get the same answer. I'm wondering if their instruction is a bit of overkill. I do want to be completely safe, though.
OK, that's two of you who say the sides can be closed. I can deal with the top and bottom open. Thank you!
I just took another look at the installation guide and it shows all four sides open, but said at least three sides need to be open, so I apparently can close the side that is not as obvious. I hope the wall doesn't look odd being away from the base wall like that, but I think it's the lesser of the two evils rather than having the stove so far into the room.
Oops! OK, one of you and I appreciate your research. Woodstock may be erring on the side of caution.
I'm not sure if you are confusing a sheet metal shield with a wonderboard/durock barrier. The wonderboard only needs to be open at the top and bottom because the flow of air goes from the bottom up and out the top opening. AFAIK, you can put a narrow grill on the opening as long as there is plenty of room for the free movement of air.
I looked at another illu
Oh, OK. I didn't realize it's different depending on the material. Thanks for clearing that up. A grill might be a good idea to finish off the top. Can you tell me where I might find that?
I was just reading up on the NFPA 211 info but I'm confused about one thing. I ended up on a Canada regulation site that said the air space board must extend out 18" on both sides. The wall ends 8" on one side. Is this a problem? There's no wall near the stove on the left after the 8", just open space.
She said the stove will have the factory rear heat shield installed. That's built with an air gap between it and the rear wall of the stove firebox. She's talking about additionally installing a wall shield to the wall behind the stove. If the stove manufacturer says this is OK to do to further reduce clearances, then it's fine to do, but the wall shield has specific configuration requirements to make it work...the 1" air gap behind and the free flow of air up from bottom and out the top are key. Rick
But if it's considered a necessary requirement for safety, it doesn't seem to matter where it is. Either it's safe to go less than 18" or it's not. I'm thinking you're saying my space is OK and Canada just has tighter rules.
This gets confusing quickly without a clear picture of exactly what's going on here. Are you installing this stove in a corner? Are you planning to install shields on both walls? Can you post a picture of the installation location? Have you thoroughly read and understood the specific installation instructions for your stove?
The only thing that matters is what the manufacturer of your specific stove says is required for the installation of your specific stove. If the manufacturer says it's permissible to further reduce clearance to a wall by using an installed wall shield, then NFPA is the guide to proper design and installation of that wall shield. Don't confuse a wall shield (attached to the house) with a heat shield (attached to the stove).
Right now I'm at the point where it seems I can get away with just three sides open, per the manufacturer, though other sites say two is fine. Three will work for me. I'm not great at uploading pictures but will if I can.
No, I understand the difference and I need both for the 12" clearance. What I didn't know about was sheet metal vs. Wonderboard for the wall. But that's cleared up now, I believe.
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