Clearances for Woodstove in New Construction

[Randy S]

Hello,

I am in the final phase of new home construction planning and have a question about stove clearances. The LR measures 24 ft. long by 12'wide; the stove(Woodstock Fireview)would be centered on the outside wall of this room, then stove pipe thru wall into a Metal chimney running up the outside of the house. I am planning on doing a chase to enclose the metal chimney on the outside. Per Woodstock's guidelines for rear clearances for this stove, they call for 36'' w/o a heat shield; 18'' w/ a heat shield. Is there a way that I can have the builder do some type of different construction for that part of the wall where the stove is to reduce clearances? My concern is that with a width of only 12 ft., I do not want the stove on a hearth to be sticking way out into the room. Can I do something similar to a pre-fab FP firebox where the stove could be backed up to the FP box, then have the stovepipe go up thru that? I will have to go thru the outside wall of the house w/ the chimney; there is a room directly above the LR, so I cannot go straight up and out.

Thanks in advance for your help/suggestions.

 

[KP Matt]

Does the stove's documentation say anything about wall shielding? I think in some/many/most cases you can further reduce the clearances (on top of what the stove's rear heat shield provides) with certain properly installed wall shielding - i.e. some sort of sheet metal, mineral board, tile on mineral board. These have to be spaced something like an inch off the wall, and need to have a certain amount of space between the floor and the bottom of the shield to allow for air flow. The stove's documentation should say. I think you may be able to reduce at least 50%. Plus you won't be radiating nearly as much heat into the wall.

 

[wg_bent]

I would read that carefully. 36" has to be clearance from a combustable wall. Make the wall out of brick, and I'll bet those clearances go way down.

Edit: I went to look at the Woodstock site, and they had this posted:

Even if the wall is non-combustible, we always recommend that the wood stove be positioned 12-18 inches from a wall to ensure the best heating. Air can then circulate behind the wood stove and you will get the benefit of the heat radiated by the back of the wood stove.

so if you can make the wall non-combustible, there's a 24" gain for you.

 

[elkimmeg]

NFPA 211 describes a reduced a wall protection system. Depending how is is done clearance can be reduced up to 66% but not less than 12" unless tested and spec and listed by the manufacturer. The other piece of the puzzel is the connector pipe. Single wall is 18" to combustiables double wall is either 6"or 9" then there are single wall pipe reduction heat shields
I you wish I can scan and post the nfpa reduction , couple 3/4 pages, that it could be sticky post, so that It would be here at all times to review. Post are limited to 6000 characters so it is a hassel to get it done

To answer your question there is an approved way to accomplish reductions

BTW Warren 4" solid brick or masonry in front of combustiable walls is only 33% reduction include a 1" airspace and it can be reduced further
Got to run I picked up the staging planks I need

 

[MountainStoveGuy]

Non combustable is defined and non combustable from the finished inside to the out side of the building. Protected surface is a non combustable against a combustable with a 1" ar space. NFPA 211 will give you a 1/3 reduction in clearance with this situation. The manufacture has to state that they allow the 211 rule to be applied to there stove. There is no clearacne to true non combustables.

 

[wg_bent]

NFPA 211 describes a reduced a wall protection system. Depending how is is done clearance can be reduced up to 66% but not less than 12" unless tested and spec and listed by the manufacturer. The other piece of the puzzel is the connector pipe. Single wall is 18" to combustiables double wall is either 6"or 9" then there are single wall pipe reduction heat shields
I you wish I can scan and post the nfpa reduction , couple 3/4 pages, that it could be sticky post, so that It would be here at all times to review. Post are limited to 6000 characters so it is a hassel to get it done

To answer your question there is an approved way to accomplish reductions

BTW Warren 4" solid brick or masonry in front of combustiable walls is only 33% reduction include a 1" airspace and it can be reduced further
Got to run I picked up the staging planks I need

Yes. Good point. Elk. I was intending a completely non-combustable wall in my assumption. By the way, this is exactly what my father had in our downstairs when we had a coal stove years ago. A free standing brick wall was put up in front of 2x4 walls with a 1" air space. That brick got VERY hot at times, but it sure was nice, and held an amazing amount of heat.

 

[begreen]

Yes, to pick up on Elk's last suggestion. The key is a non-combustible surface behind the stove. We are doing a similar project and will have a tiled (or maybe stone tiled?) surface on durrock (cement board) that will be attached to the wall with 1" non-combustible spacers.

From Woodstock's site: (broken link removed to http://www.woodstove.com/pages/installation.html)
Do not assume that a wall is not combustible because it has a nonflammable surface. A wall with any combustible materials in it must be considered combustible. For example, a brick wall attached to wood studs is to be considered a combustible wall. Given time, heat will pass through bricks and heat the wood, possibly resulting in a fire. Similarly, wood-framed walls which are covered with tile, stone, or fire-rated sheetrock must be considered combustible.

Wood Stove Clearances

If you wish to install your wood stove closer to a combustible wall than standard clearances will permit, you have two options:

1. You can install a heat shield on the wood stove and/or wood stove pipe. Our factory-made rear heat shields and pipe shields are unobtrusive and easy to install, and will allow you to reduce the clearance to a combustible surface.

2. You can install protection on the wall such as cement board covered with ceramic tile. A properly chosen wall protector will not only reduce the amount of heat absorbed by the wall but it can also enhance the appearance of the wood stove installation.

Note: If you are installing a wall protector it is necessary to leave a 1" ventilated air space behind it. This ventilated air space will prevent excess heat from being trapped between the wall protector and the wall. The wall protector can be attached to the studs using long screws and 1" ceramic spacers that do not transmit heat.

Even if the wall is non-combustible, we always recommend that the wood stove be positioned 12-18 inches from a wall to ensure the best heating. Air can then circulate behind the wood stove and you will get the benefit of the heat radiated by the back of the wood stove.

- I would add that you want to have this back wall protector not only spaced from the wall surface, but also with at least a 1" gap at the bottom and open at the top to allow air to circulate behind it. That's what they mean by "ventilated" space.

 

[Randy S]

Thanks guys for all of your input. I will take this info. back to the builder.
I appreciate your help.

SG

 

[elkimmeg]

Did you know in Canada the space is 2" not the 1" used in USA, also the distances are 4' not the generic 3' in USA

Point being if you were to go 1.5 " air space there is no penalty for making it safer and exceeding code But it can not be reduced further because increasing the air space. You just added 50% safer margine.

Codes are just, that minium safety standards

 

[elkimmeg]

Non combustable is defined and non combustable from the finished inside to the out side of the building. Protected surface is a non combustable against a combustable with a 1" ar space. NFPA 211 will give you a 1/3 reduction in clearance with this situation. The manufacture has to state that they allow the 211 rule to be applied to there stove. There is no clearacne to true non combustables.

MSG correcct But every manufacture list the standard to which the stove is tested to Be the canadan standard or IBC or NFPA 211

Hard not to find tested to NFPA 211 standards on any soild fuel burning appliance sold in USA ZolZang excluded
Once the standard is reconsise it can be applied to the installation For instance your own product
Harman Oakwood Page 11 of the manual. The NFPA standard is called in on every stove

Clearance distances may only
be reduced by using methods approved by either the CAN/
CSA B365 standard (Canada) or NFPA 211 (U.S.) Con-
tact your building authority for information if you are inter-
ested in reducing clearance distances other than those pre-
sented here.

 

[Rhone]

Encasing the stove in an enclosure is a bad idea. Stoves are meant to be in the open and don't work particularly well when encased (if you want to encase it you're best with a fireplace insert).

So, work on modifying the walls and such but skip the idea of making an enclosure. You want it to be in the open.

 

[mlouwho]

Have you thought about doing a bump out "chase". You could do an "alcove" 8' wide & 24" deep. It would add minimal cost to construction, but move the stove to the edge of the room giving you more space, but would still keep good clearance & air flow around the stove. Just a thought......

 

[elkimmeg]

I hope Southern Gent checks back in. Mlouwho that is a great idea. He is in the planning stages. all he would have to do is buy about 6 to 8 longer floor joist minimal additional framing involved. Infact he might be able to build a chase to house the chimney up the side of the building. Insulate the chace and it would draft almost like within conditioned spaces.

 

[Randy S]

Hey Mlouwho and Elk,

The bump out- are you talking about an alcove that would go floor to ceiling, or just high enough(3 /12 - 6 ft) to set the stove back on the edge of the room. That's why I was using the analogy about the pre-fab fireplace set up, I didn't know how else to explain it. The exterior of the house will be brick, so the chase would be framed up, insulated, then brick up the framing.

All of this is good info.. Appreciate your feedback.

SG

 

[mlouwho]

I would do the alcove open floor to ceiling, I think it would look more like it belongs and give the best airflow/circulation. Like Elk said, a few extra long floor joists & it would be built cantilevered out, kind of like a bay window. You were talking about building a chase around your pipe anyways, this way your pipe could go straight up. I'd put a ceiling inside the chase at the 8' level, double wall pipe to that ceiling & class A straight up from there.

 

[elkimmeg]

If in the planning stages and doing a brick front or facing. You may be advised to also bump out the foundation, to transfer the weight of the brick to the foundation. Not such a good idea to have the overhang support the addittional weight?
From there you could also use metal framing studs your distance from combustiables would be from the outside sheeting You could reduce it 1/3 but starting from the sheething. Now if you had a rear exit stove, you could use a tee which would have a bottom cover and allow for easy cleaning of the flue. A short connector pipe to the tee then straight up

so review of what I suggest: Foundation bump it out to the desired length. Use metal studs (This will gain 4" more) insulate the stud cavities sheeth the outside build the brick facing in front towards the room and you can legally place the stove 16" infront of the brick facing. If you use wood studs add 4" more or 20 " infront of the brick

 

[Randy S]

Thanks guys for the input. I like the idea of doing a bump out on the foundation so as to support that extra weight. The alcove thing I really like, due to the fact that the pipe can go straight up. The Woodstock Fireview is the stove I am making arrangements to purchase; it vents out the back, so this could work great.

Thanks again for your suggestions and feedback.

SG