Would installing steel studs increase safety

[quicktypez]

Hi,

I am installing a Jotul F100. My stove has enough clearance to the combustibles. I do not need a heat shield.

I want to replace a portion of the wood studs with steel ones. Only the portions that are exposed. Meaning I would cut the wood studs in half, and replace it with a steel ones. Then I would attach hardiebacker to the steel studs and tile that puppy up.

Question: Is there any benefit in doing so?

Thanks!

 

[begreen]

Not really.

 

[kennyp2339]

If anything the wall with the horizontal roamex and below it will be the coolest part of the wall, make sure you have a minimum of 18" if using single wall pipe from any part of the wall, you may want to consider building and installing a heat shield for insurance. There fairly simple to do.

 

[begreen]

Yes, if the goal is to make an extra layer of protection a ventilated wall shield would be most effective, but still overkill. If that is desired, an option would be to build a hearth pad that is the same height as the 2x4 sill in the wall. Brush on some black paint at the base of the stud cavities. Then sister metal studs onto the existing stud, but protruding 1" in front of the wood studs. Then attach the cement board to the metal studs keeping it 1" above the hearth so that there is a 1" gap at the bottom. Leave it open on top so that air can convect freely behind the wall shield. Tile the cement board. If you want to cap the wall shield with a mantel, be sure to cut down the cement board between the studs a little so that you have 1" opening slots under the mantel. If the mantel is wood, be sure clearances to the stove are proper.

 

[quicktypez]

Yes, if the goal is to make an extra layer of protection a ventilated wall shield would be most effective, but still overkill. If that is desired, an option would be to build a hearth pad that is the same height as the 2x4 sill in the wall. Brush on some black paint at the base of the stud cavities. Then sister metal studs onto the existing stud, but protruding 1" in front of the wood studs. Then attach the cement board to the metal studs keeping it 1" above the hearth so that there is a 1" gap at the bottom. Leave it open on top so that air can convect freely behind the wall shield. Tile the cement board. If you want to cap the wall shield with a mantel, be sure to cut down the cement board between the studs a little so that you have 1" opening slots under the mantel. If the mantel is wood, be sure clearances to the stove are proper.

Hmm, I like the idea. I can put Roxul insulation between the wood studs as I will not be burning the stove all the time so I cannot let the heat escape. Maybe I will cover the Roxul up with foil or something to prevent it from getting dusty. Then I can install 1" metal channels on the wood studs and attach hardiebacker to that, and tile it. So not much extra work.

But you did say it's an overkill. Jotul F100 allows for 8" from the back (to an unprotected surface) and 17" on the sides.

I'm 9" at the back and 17.5" on one side (the corner wall extend half-way to the vertical center of the stove), and nothing on the other side. Would a shield still be an overkill in my scenario?

 

[begreen]

8" clearance from the back is for an installation using double-wall stove pipe. If using single-wall, the pipe clearance of 18" overrules the stove clearance. 17" at the side is the minimum for double-wall stove pipe. These clearances are the minimums. There is no harm in exceeding them. Jotul's classic stoves are cast-iron and quite radiant so a bit of additional protection may provide more peace of mind, but the stove has been tested to these minimums.

If this is an exterior wall then adding insulation would be a good idea, for the entire wall.

 

[quicktypez]

8" clearance from the back is for an installation using double-wall stove pipe. If using single-wall, the pipe clearance of 18" overrules the stove clearance. 17" at the side is the minimum for double-wall stove pipe. These clearances are the minimums. There is no harm in exceeding them. Jotul's classic stoves are cast-iron and quite radiant so a bit of additional protection may provide more peace of mind, but the stove has been tested to these minimums.

If this is an exterior wall then adding insulation would be a good idea, for the entire wall.

Ok great thanks for the info. I am indeed planning to use a double wall pipe.

I have a bit of a dilemma. I can go with no heat shield, having just cleared the minimums.

Or, I can add a shield. Only a tiny bit of additional effort. But the side is giving me grievances - the bit of wall on the side that's protruding from the wall.

My installation needs to be WETT certified. As per WETT spec:

10. "Mounting hardware must not be located closer than 200 mm (8 in.) from the vertical centre line of the appliance."

http://www.wett-inspection.com/reducing-clearances/

The problem is that the side shield will be secured by 1" spacers (or metal run channels) that we be located directly across the oven, from the side. Meaning the radiant heat will hit the shield and the spacers (or channels) which can can then transfer the heat to wood frame underneath. I am not sure what the inspector would say in that situation. In the picture the green tape sort of outlines the stove.

Also,

8. Shield extension beyond each side of appliance: 450 mm (18 in.).

The side heat shield will not extend 18 each way. In one direction - there is the back wall. In the other direction - the wall ends. So the side shield itself will only be 24 in inches or so in width. Once again, not sure if that's ok or not as per WETT spec ...

P.S. this is my first stove so I may be reading the WETT stuff all wrong.

 

[begreen]

Sounds like you're all WETT. (j/k) WETT requirements are a bit stiffer than in the US.

10. "Mounting hardware must not be located closer than 200 mm (8 in.) from the vertical centre line of the appliance."
This is so that the screws are not directly behind the stove pipe and center of the stove. Considering that your stove does not need a shield and you are not going for reduced clearances I'm not sure if this is even an issue. My personal opinion is that with the tile covering, the heat is diffused enough that the amount transferrable via the screw would be negligible and not a hazard. Maybe others would disagree.

5. Shield extension beyond each side of appliance: 450 mm (18 in.).
As I understand it that would only be applicable if the wall continued past the 24" wing wall. Once you are past the end of the wall you are in free air and there is no combustible to shield against.

You could always ask the inspector and provide drawings ahead of time for approval, though it sounds like in this case the wall shielding is just for peace of mind if the documented clearance requirements have already been met without the shielding.

 

[quicktypez]

Sounds like you're all WETT. (j/k) WETT requirements are a bit stiffer than in the US.

10. "Mounting hardware must not be located closer than 200 mm (8 in.) from the vertical centre line of the appliance."
This is so that the screws are not directly behind the stove pipe and center of the stove. Considering that your stove does not need a shield and you are not going for reduced clearances I'm not sure if this is even an issue. My personal opinion is that with the tile covering, the heat is diffused enough that the amount transferrable via the screw would be negligible and not a hazard. Maybe others would disagree.

5. Shield extension beyond each side of appliance: 450 mm (18 in.).
As I understand it that would only be applicable if the wall continued past the 24" wing wall. Once you are past the end of the wall you are in free air and there is no combustible to shield against.

You could always ask the inspector and provide drawings ahead of time for approval, though it sounds like in this case the wall shielding is just for peace of mind if the documented clearance requirements have already been met without the shielding.

Hi thanks for helping me though this. I did call the inspector and emailed him the pic. He did recommend not to bother with the heat shield. I don't think he believes in the "piece of mind" thing. He has a more scientific approach to things I guess. If the clearances are met then I am good. Simple as that

 

[begreen]

While it doesn't qualify for clearance reduction you could add some extra insulation behind the cement board for more peace of mind. This would be simpler than the steel stud approach. Can you get Durock NexGen cement board? That has almost twice the insulation value as hardibacker. You could put up two layers of Durock NexGen for greater insulation behind the tile walls. That will bring the insulation up to R=.78. Or you could put a layer of 1/2" micore behind the cement board for even more insulation. It's not required, but it is an option.

 

[quicktypez]

While it doesn't qualify for clearance reduction you could add some extra insulation behind the cement board for more peace of mind. This would be simpler than the steel stud approach. Can you get Durock NexGen cement board? That has almost twice the insulation value as hardibacker. You could put up two layers of Durock NexGen for greater insulation behind the tile walls. That will bring the insulation up to R=.78. Or you could put a layer of 1/2" micore behind the cement board for even more insulation. It's not required, but it is an option.

Great, Micore 300 is not overly expensive so I will try to use that. If not then Durock NexGen is easy to come by.

 

[begreen]

Sounds good, just be sure the cement board is the top layer. Tile will not bond to micore.

 

[quicktypez]

Sounds good, just be sure the cement board is the top layer. Tile will not bond to micore.

Ha, finding Micore was easier / cheaper then I thought.

4ft x 4ft Micore SB is $15 CAD a piece

4ft x 8ft Micore-300 is $30 CAD a piece

I found a distributor in Toronto.

 

[quicktypez]

p.s. here's a distributor in case anyone is looking for one in GTA ares: http://www.formit.ca

 

[georgepds]

" Maybe I will cover the Roxul up with foil or something to prevent it from getting dusty. "

The other thing the foil does is distribute the heat so there are no really hot spots... has to be thick foil to work properly.. think aluminium roof flashing

 

[WoodyIsGoody]

I did call the inspector and emailed him the pic. He did recommend not to bother with the heat shield. I don't think he believes in the "piece of mind" thing. He has a more scientific approach to things I guess. If the clearances are met then I am good. Simple as that

I agree with the inspector. The scientific approach is what provides peace of mind.

There are some regulations you could go overboard on that might actually increase your safety but putting steel studs behind a conforming installation is not one of them. Increasing the required 16" hearth extension (in front of the firebox opening) is one of them. That said, conscientious operation is the biggest safety factor.