# Need advice about the one inch spacer wall for wood stove installation



## Gin (May 18, 2015)

Hello!  Some of you may remember me from several weeks back when I was researching for our plans to install a wood burning stove.  We purchased a Woodstock Fireview, had a hearth built and tiled per the instructions from Woodstock and will have the stove delivered this week.  We wanted to get the stove as close to the wall as possible and were advised by Woodstock to purchase the rear heat shield and install a one inch spacer wall to allow the heat to flow up and away from the interior wall.  We plan to do that and tile it as well, over Durock.  An employee at the tile store was concerned the tile will be too heavy for the Durock wall.  It will be screwed in to the studs in the interior wall and our chimney guy believes it will be secure.  Should I be concerned?  Has anyone here done a wall spacer installation with tile?  Thanks for your help once again.


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## DAKSY (May 18, 2015)

If you use steel 2x4s as your spacers & screw through the Durarock & the steel stud into the framing members in the wall you should be good to go. You'll have 1-1/2" of air flow...
You can use as many screws as you think you'll need for support. Just make sure you also leave a minimum of 1" air flow space at the bottom, too.


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## Highbeam (May 18, 2015)

Building an fancy air gap wall shield like that only accomplishes anything if the owner's manual specifies a reduction in clearances by doing it. Is this just a "feel good" wall shield or are you trying to build it with this air gap for a real benefit such as a lesser clearance to the wall?


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## begreen (May 18, 2015)

There are many NFPA wall shields that are tiled, brick or stone veneered. Properly hung it is not going anywhere. Screw it once every 8" per Durock directions. Another method for creating the 1" gap is to snap off long 3" wide strips of Durock, then double them up and mount them to the wall studs as firring strip spacers for the sheets of Durock.

The Fireview manual acknowledges wall shielding for clearance reduction. A proper NFPA 211 wall shield should allow a clearance reduction front the back of the stove to 12". Note that this clearance is measured to the nearest combustible which in this case is the wall behind the wall shield.


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## Gin (May 18, 2015)

DAKSY said:


> If you use steel 2x4s as your spacers & screw through the Durarock & the steel stud into the framing members in the wall you should be good to go. You'll have 1-1/2" of air flow...
> You can use as many screws as you think you'll need for support. Just make sure you also leave a minimum of 1" air flow space at the bottom, too.



Thank you for this information.  I know the contractor mentioned steel screws, so that's good.  Don't know what he plans for spacers but now I know of the steel option.


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## Gin (May 18, 2015)

begreen said:


> There are many NFPA wall shields that are tiled, brick or stone veneered. Properly hung it is not going anywhere. Screw it once every 8" per Durock directions. Another method for creating the 1" gap is to snap off long 3" wide strips of Durock, then double them up and mount them to the wall studs as firring strip spacers for the sheets of Durock.
> 
> The Fireview manual acknowledges wall shielding for clearance reduction. A proper NFPA 211 wall shield should allow a clearance reduction front the back of the stove to 12". Note that this clearance is measured to the nearest combustible which in this case is the wall behind the wall shield.



Thanks for this post.  It's good to know we can use Durock strips as the spacers, since I don't know what the contractor has planned.  I should probably just trust the contractor, who has a great reputation, but since it's fire and all, I'm being a little compulsive, I guess. I also like the idea of using a lot of screws for extra strength. I couldn't find any pictures at Woodstock that showed what looked like a one inched spaced fire wall so I called them too.  They said no problem with the tile, but I have gotten much better, detailed information here and I thank you all for that.  I feel very comfortable with the tile now.  Funny how one ill-informed person can mess with my head so much.  I'll be glad when this project is done!


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## begreen (May 18, 2015)

Here is an article on building an NFPA 211 wall shield. Besides the 1" air space behind it be sure the bottom and top are open and clear by an 1" to allow good airflow behind it. 
https://www.hearth.com/econtent/index.php/articles/stove_wall_clear
As long as you are building the hearth, consider putting down a double layer of the 1/2" Durrock for a little added protection. It's cheap and good insurance.


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## Gin (May 18, 2015)

begreen said:


> Here is an article on building an NFPA 211 wall shield. Besides the 1" air space behind it be sure the bottom and top are open and clear by an 1" to allow good airflow behind it.
> https://www.hearth.com/econtent/index.php/articles/stove_wall_clear
> As long as you are building the hearth, consider putting down a double layer of the 1/2" Durrock for a little added protection. It's cheap and good insurance.




Very good article.  Thanks.  The diagram is very helpful as well.


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## notshubby (May 19, 2015)

also remember whatever is used for fasteners must not be used in the area directly behind the appliance or connector


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## Gin (May 19, 2015)

notshubby said:


> also remember whatever is used for fasteners must not be used in the area directly behind the appliance or connector



Yes, I I saw that on the page with the diagram.  Thank you.  I'm assuming the chimney guy knows this, but I'll be watching, just in case.  I'm sure he'll love that.  ;-)


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## Chinneysweep187 (May 19, 2015)

Stove clearance is 12" minimum behind the stove there is no way to reduce that and meet code . This would be for your own peace of mind . I would go with Durock wall w/ tile ,ceramic spacers


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## bholler (May 19, 2015)

Chinneysweep187 said:


> Stove clearance is 12" minimum behind the stove there is no way to reduce that and meet code . This would be for your own peace of mind . I would go with Durock wall w/ tile ,ceramic spacers


Yes but with out the wall sheild the stove needs to be 18" from the combustible wall if it has a factory heat sheild or 30 with out it.  So you would still get at least a 6" reduction


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## bag of hammers (May 19, 2015)

DAKSY said:


> If you use steel 2x4s as your spacers & screw through the Durarock & the steel stud into the framing members in the wall you should be good to go. You'll have 1-1/2" of air flow...
> You can use as many screws as you think you'll need for support. Just make sure you also leave a minimum of 1" air flow space at the bottom, too.


+1  I used steel studs (cut to length) for the heat shield spacer on my last stove.  1/2" durock on top of that - solid as a rock for years.   No tiles though (didn't care about that - just a rough finish weekend cabin).  The air gap at the bottom is critical.  I had this over cabin grade t&g pine where i needed a few inches clearance reduction and the wall behind the shield barely got warm.  Great peace of mind IMHO...


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## notshubby (May 19, 2015)

Chinneysweep187 said:


> Stove clearance is 12" minimum behind the stove there is no way to reduce that and meet code . This would be for your own peace of mind . I would go with Durock wall w/ tile ,ceramic spacers



unless ul listed appliance allows further reduction.  nfpa states any ul listed clearance supercedes theirs. but you cant stack them. so if your appliance says say 10 inches for example, you can use the listings 10 inches although its under the 12 inch min nfpa 66%  reduction. but cannot reduce the 10 inches by 66% or 50%.

example my Englander says with side and rear heat shields and double wall stove pipe  appliance clearance to combustable back wall is 5 inches. scroll over to the clearance with nfpa 211 protected surface is still 5 inches.


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## bholler (May 20, 2015)

notshubby said:


> unless ul listed appliance allows further reduction. nfpa states any ul listed clearance supercedes theirs. but you cant stack them. so if your appliance says say 10 inches for example, you can use the listings 10 inches although its under the 12 inch min nfpa 66% reduction. but cannot reduce the 10 inches by 66% or 50%.
> example my Englander says with side and rear heat shields and double wall stove pipe appliance clearance to combustable back wall is 5 inches. scroll over to the clearance with nfpa 211 protected surface is still 5 inches.


Yes but i already gave the info per the ul listing for this stove 30" with no shield 12" with one still a large reduction and still well worth doing.  if it is a listed stove 211 doesn't mean much just follow the instructions


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## kennyp2339 (May 20, 2015)

You may get the stove very close to the wall  and have it protected properly, but you will still need to have the proper clearances on the chimney pipe exiting the stove. What I'm trying to say is don't forget about your smoke pipe while in the design stage. There is a difference between single wall and double wall pipe. If I remember correctly single wall needs at least 18" clearance's to combustibles, and double is 12" from outside wall to nearest combustible.


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## bholler (May 20, 2015)

kennyp2339 said:


> If I remember correctly single wall needs at least 18" clearance's to combustibles, and double is 12" from outside wall to nearest combustible.


Single wall is 18" but with a wall sheild it goes down to 6" and double wall is 6" but that is all in the instructions for the stove the clearances they set override code so go by what ever the instructions say


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## Jan Pijpelink (May 20, 2015)

Something like this.


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## Chinneysweep187 (May 20, 2015)

single wall is 18" and double wall is 9" half of 18 obviously . And yea if your stove manufacturer says you can be closer then it's obviously okay. I was just making sure you weren't trying to put it closer than 12" but I still stand by my recommendation Durock wall with tile ,ceramic spacers that's the best option. Steel studs are okay but why not go ceramic with the resistance to heat and the cheap cost .


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## bag of hammers (May 20, 2015)

Chinneysweep187 said:


> Steel studs are okay but why not go ceramic with the resistance to heat and the cheap cost .


I'm a scrounger - spare parts in my case - studs left over from sauna project - worked like a charm.


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## Chinneysweep187 (May 20, 2015)

In that case don't blame you at all haha . But if your buying Raw materials.....


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## bholler (May 20, 2015)

Chinneysweep187 said:


> single wall is 18" and double wall is 9" half of 18 obviously .


No double every double wall i have ever seen specs on or used is 6" it is just a pipe with a ventilated shield.  And a ventilated shield gives you 2/3 reduction not 1/2.  We prefer to use steel studs also i think they are easier to work with personally but any noncombustible will work it comes down to preference.


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## Chinneysweep187 (May 20, 2015)

absolutely right it's 8" or 9" to ceilings and 6" for walls my mistake


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## bholler (May 20, 2015)

What brand has 8" or 9" to ceiling There may be some for sure but the stuff I have used is 6" no matter what.  But like i said you need to follow the manufacturers clearance requirements what ever they say goes


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## Chinneysweep187 (May 20, 2015)

simply Google double wall stove pipe clearance and you will see many that require 8" to the ceiling


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## bholler (May 20, 2015)

Ok i see the stuff from woodland direst calls for 8 my bad.


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## begreen (May 20, 2015)

bholler said:


> What brand has 8" or 9" to ceiling There may be some for sure but the stuff I have used is 6" no matter what.  But like i said you need to follow the manufacturers clearance requirements what ever they say goes


8" to ceiling is the spec for DVL . Based on personal experience I think it is a good idea to increase the clearance for the ceiling above a horiz. section of double-wall connector. It still radiates a lot of heat.


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## bholler (May 21, 2015)

begreen said:


> 8" to ceiling is the spec for DVL . Based on personal experience I think it is a good idea to increase the clearance for the ceiling above a horiz. section of double-wall connector. It still radiates a lot of heat.


Yeah i see than many have that now i apologize again


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## Chinneysweep187 (May 21, 2015)

begreen said:


> 8" to ceiling is the spec for DVL . Based on personal experience I think it is a good idea to increase the clearance for the ceiling above a horiz. section of double-wall connector. It still radiates a lot of heat.


I agree more heat than most people and I have thought


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## begreen (May 21, 2015)

Folks seem to think that double-wall stove pipe is strongly insulated, it is not. There's only a thin air gap between the outer and inner layers. I have been surprised at wall temps measured even with double-wall 12" from a vertical wall. You still get quite a bit of heat radiated to the room from this pipe.


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## JarodL (May 11, 2016)

where do you find cement board screws long enough to go through the 1/2" cement board and then the 1" air gap? I estimate I need at least 3" screws.


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## begreen (May 11, 2016)

You will need to use a substitute like 2.5 or 3" drywall screws.
http://www.homedepot.com/p/Grip-Rit...t-Drywall-Screws-1-lb-Pack-212CDWS1/100180312
http://www.homedepot.com/p/Everbilt...int-Drywall-Screw-5-lb-Pack-E3CDWS5/205461029


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## JarodL (May 11, 2016)

begreen said:


> You will need to use a substitute like 2.5 or 3" drywall screws.



Thank you. I was afraid the drywall screws' head wouldn't be wide enough.


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## begreen (May 11, 2016)

Not ideal but the longest cement board screw is only 2 1/4" I think. If you are screwing directly into studs that will get you 3/4" purchase. If you need longer then I think drywall screws are the next best answer. Screw every 8" and it should be ok.


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## bholler (May 11, 2016)

I would use deck screws over drywall screws for sure drywall screws are not very strong.  There are also some screws with larger heads meant for framing that may work even better.  But we typically just use deck screws with no issues.


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## larry08 (May 11, 2016)

I just built a shield for my stove, spaced 1" from the drywall.  I used spax 3 1/4" multi mateirial screws.  They seem to be holding great, spaced about 8" apart on 16" centers.


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## Simonkenton (May 14, 2016)

Do what I did. Install a copper heat shield. Easy to get your one inch air space, plus an air space at the bottom. I hammered my copper heat shields and it really looks good, the pic does not do it justice.
A lot less trouble than duroc and tile.

I don't know anyone else who has used copper for a heat shield but I can tell you it is extremely effective, because copper reflects almost 100 percent of the heat that strikes it. I can have my Jotul cranking at 650 degrees and can hold my hand against the shield, and it feels cool!  Can't be over 85 degrees.


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## kennyp2339 (May 15, 2016)

Simon - that looks so nice with you true log house walls, that's something out of that barn wood builders show, you got any other pics of the house?


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## bholler (May 15, 2016)

Simonkenton said:


> because copper reflects almost 100 percent of the heat that strikes


?????  Copper conducts heat very well what do you mean it reflects almost 100% of the heat that hits it?    You heat shield looks great and i am sure it works well but that statement was totally wrong.   The only problem i wee with using copper is the price.


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## Simonkenton (May 15, 2016)

If it absorbs heat, why is the heat shield, standing 14 inches from a 650 degree stove, barely above room temp?
Have you ever used a copper heat shield?

As for cost, I am not sure. Haven't bought any copper lately, I know the cost is up. But you can install a copper heat shield in ten minutes.

How long does it take to install duroc and lay tile upon it?


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## Simonkenton (May 15, 2016)

Thanks for the compliment kenny. Here ya go:


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## bholler (May 15, 2016)

Simonkenton said:


> Have you ever used a copper heat shield?


Yes I have many times



Simonkenton said:


> If it absorbs heat, why is the heat shield, standing 14 inches from a 650 degree stove,


Because it dissipates that heat quickly to.  Look at the properties of copper it is an excellent heat conductor



Simonkenton said:


> As for cost, I am not sure. Haven't bought any copper lately, I know the cost is up. But you can install a copper heat shield in ten minutes.


The last chimney i flashed in copper was almost $300 just in materials and that would not have done a heat shield.  There was a time we did copper for heat shields and smoke shields but not anymore.  We use painted steel now or occasionally stainless


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## Simonkenton (May 16, 2016)

OK, you have a lot of experience with a copper heat shield. If it transmits heat, does it not transmit the heat right into the wall one inch behind it?
Is copper a good material for a heat shield?

I can do a test when I get back home. I would do a test right now but am an over the road truck driver and won't get home for a week.
I have a stove top thermometer but the simple thing to do would be to feel the log wall right behind the heat shield.
My Jotul is installed according to manufacturer's spec but that wall was getting quite warm so I installed the copper.
When I get back, even if it is a warm spring day I am going to fire up the Jotul and feel the wall behind the heat shield.


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## begreen (May 16, 2016)

Sheet metal be it copper, stainless or plain galvanized is going to stay pretty cool behind a wood stove. We had regular sheetmetal about a foot away from the side and back of our 602 and it never got hot. It is reflecting the heat and cooled by convection of the air behind it which never got much above 80 or 85F. That is the nature and benefit of a wall shield.


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## bholler (May 17, 2016)

Simonkenton said:


> OK, you have a lot of experience with a copper heat shield. If it transmits heat, does it not transmit the heat right into the wall one inch behind it?


No I never said it did.  It stops the transfer of radiant heat and converts it into convective heat.  That it totally different than "copper reflects almost 100 percent of the heat that strikes it"



Simonkenton said:


> Is copper a good material for a heat shield?


Yes copper is a fine material for a heat shield like i said the only issue is the price.



Simonkenton said:


> I have a stove top thermometer but the simple thing to do would be to feel the log wall right behind the heat shield.
> My Jotul is installed according to manufacturer's spec but that wall was getting quite warm so I installed the copper.
> When I get back, even if it is a warm spring day I am going to fire up the Jotul and feel the wall behind the heat shield.


And it will be much cooler due to the fact that that copper is blocking the radiant heat that it the reason for the 1"gap.  If it was reflecting the heat as you say there would be no need for the gap.


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## CheapBassTurd (May 23, 2016)

Metallurgically copper is second only to the gold/platinum/silver/lead family in heat 
and electrical conduction.

Many safes have a copper wall that can't be cut with a torch due to it's excellent 
dissipation even though it melts at under 2,000 degrees.  An oxy/acl torch goes 
to about 5,110 deg F/ 3,480 C.

The copper wall gives off it's heat so fast by sucking it to the coldest corners of the 
sheet/ plate while radiating so quickly simulteneously it just doesn't get hot.  Before 
the stuff got expensive it was used in mass as being safer than lead and cheaper 
than the precious metals.

Steel is fine.  Next is galvanized steel, aluminum, tin, and copper (in order) being best 
here in the practical world.

(I'm a newbie stover, so it felt really nice to contribute in the area where experienced
and educated, metal properties)

CheapMark


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