I am installing a wood stove in a soon to be constructed alcove (the structural wall into the garage from the living room). I need to make the alcove fire proof like a fireplace, but have never laid brick or other rock. Here's my plan: Open an area of the wall and frame in the box for the stove using steel studs. I will then screw into the studs 1/2" hardiboard or similar cement board to create the space. The top of the stove will be the hottest area naturally, and my wife wants a mantel. Consequently, the distance will be 24" from the stove top, which is very close. I think I can wrap the whole box in ceramic fiber wrap (2300 degree resistance), then put sheetrock on the other side of the studs to give a 3.5" air gap. I will put on some kind of stove or brick on the inside of the box with mortar. On the top, the connector pipe will go into the thimble, which will exit the box into the chimney and have some form of insulation, probably wrapped with the ceramic fiber.
Will that do the job since it will not meet the code for diistance to noncombustibles?
Hi Michael; Welcome to Permies!
I'll try to answer your questions.
From what I read . Your going to use steel studs and face them with 1/2" hardy board. Adding brick in front of that will give you mass to hold heat.
How large an area is this ? Mantels are generally 5' or longer? Stove pipe would visually split your mantel, or would your mantel be on the side ?
How tall is the ceiling ? Are you planning on "metalbestos" insulated chimney pipe to go thru the ceiling ?
I'm not sure about what your calling a box... Ceramic blanket from china can be every bit as hazardous as fiberglass. Its also rather expensive. Rock wool might be a cheaper option.
Now as far as insurance and code.
Every state / county / city can have different rules. The only one that I believe all will agree on is the chimney. They all like the metalbestos insulated chimney system. (Has other brand names as well)
If you are currently building this house and definitely want real insurance that will pay... I highly recommend getting your insurance guy involved NOW before you start building.
Most modern wood stoves have clearance requirements to combustibles in the 10-18" range, depending on the model and any incorporated shielding. I think you're WAY over-designing your setup, unless you have an old or DIY-built stove. You can probably save a whole lot of money and effort if you look up the clearance requirements and only build what you need to meet those. Steel studs and whatnot is most likely overkill.
Edit to add: It clearance to combustibles that matter. You can have non-combustibles as close as you'd like.
Additional edit to add: I would recommend you check out hearth.com. That is a forum dedicated to wood heat. You can get excellent advice there for what you are wanting to accomplish.
posted 10 months ago
The stove is about 2'x2', and I will place in a 4'x4' box. The stove pipe will be in the back of the box, and will need to go through the hardiboard into a thimble, then will attach to a triple wall chimney. The mantel will be on the on top of the stove, and I will do a noncombustible surround of the stove that the mantel will sit on. Tell me more about the ceramic fiber blanket. I see that it is noncombustible, and is used in kilns, etc.
Thanks for the help!
The stove is 2 yrs old. so will be fine with clearances on the sides and back. The distance to combustibles on the top is 54", and I need to reduce to 24", and that is the hottest part of the stove. I will need to have the stove out 7" into the living room as well, so the whole front of the wall will be hot, so the metal studs will be necessary. I am trying to ensure that I meet code and won't have a fire, so if it's overkill, I am willing. Even with the noncombustibles, the heat will go through into wood, so I want to ensure that over time, nothing will get hot enough to ignite in the wall.
Thanks for the help
Location: Northern Puget Sound, Zone 8A
posted 10 months ago
Yes, if you have combustibles under the non-combustibles, you still need clearance. That clearance is dependent partly on the R-value of the non-combustible materials. There are codes that define that clearance based on how you construct the alcove. The air gaps, for example, have to be vented top and bottom so that natural convection will bring cool air into that gap and maintain the effectiveness of that insulating effect. Generally you are better off to add heat shields to the stove than build the shielding into the walls when it comes to reducing clearances.
So a 4 x 4 box, open only on the front ? Won't that limit how much heat gets into your room?
Or are you thinking the surrounding mass will be your radiator?
Sounds like your chimney is all up to code.
I've never heard of enclosing a wood burner that way but...
If it keeps your wife happy and your family safe then no harm done.
Is it overkill ?
In my opinion , probably, but its your opinion that matters.
Here's what I know.
Ceramic blanket is an awesome insulator. Widely used in refinery's and any extreme heat locations.
I have used it myself to seal a metal barrel to masonry with no leakage at all!
It is readily available to the general public thru ebay.
Any that is coming out of china will be very reasonably priced. It is also hazardous! As bad or worse than asbestos.
One Permies staff member bought some for his RMH. He stated a full tyvec suit with respirator should be used.
There is a safe brand easily available. Morgan super wool. Completely non toxic. No itching , no fibers going in your lungs.
Not nearly as cheap though. Well worth it. It is a pleasure to work with.
Here is a link to post of mine) https://permies.com/t/93198/ceramic-fiber-blanket
Not all who wander are lost... J.R.R. Tolkien
posted 10 months ago
Yes, I understand the ramifications of placing the stove into an alcove, or box so to speak. The front will extend about 7" into the room, and I will have the stove blower as well as a secondary blower I will buy installed to blow the hot air into the room. It originally was going to be a corner install in the room, but my wife wants it in an alcove (like inside a fireplace-look at Pinterest for an idea) so she can place chairs to the left and right.
I'll check the link, but I have a respirator and tyvek suit, so will probably go with the cheaper option.