chimney too close to combustibles

[RustyShackleford]

My stove sits in a masonry alcove at the edge of where my cathedral ceiling great room
transitions to a loft above the regular-ceiling rear part of the house. The support for
the chimney is in the edge of the loft floor. The chimney rises up through the loft,
through the ceiling of the loft, and on out through the attic and roof.

It was supposedly installed by "certified professionals" 20 years ago when the house was
built, and like many here, I'm finding on closer inspection that a basic requirement was
not met. Specifically, the chimney passes only 1-3/8" away from a horizontal 2x6 board
that forms the railing of the loft (the pickets are behind the 2x6, so much farther away).

I'm honestly not that worried, because it's been that way for 20 years, and there's never
been a sign of trouble; the 2x6 does not show any signs of overheating at the point where
the chimney is too near. But I've never had a chimney fire either (although, knock on wood,
as clean as my chimney stays, I don't plan on one - but who does ?).

I tempted to leave it alone. But if I wanted to try to deal with this, what would folks recommend ?
I'm not going to move the chimney or 2x6; just too much trouble for my degree of concern.
I'm thinking some kind of shield, perhaps a piece of metal, halfway between the 2x6 and the
chimney, screwed into the 2x6 with spacers holding it in the right position. Or maybe a piece
of tile on the 2x6, but tile is 1/4" thick or so, so then the spacing is that much less.

Ideas ?

 

[Todd]

I can see where something like that could bug you. If you can't easily move the 2x6 I think I would try your shield idea just for peace of mind. You never know, they make that 2" clearance for a reason and over time the 2x6 can lower it's light off temp. Have you flelt the pipe temp during a good hot burn?

 

[daryl]

Is it possible to do a half moon cut on the 2 X 6 you only need5/8".Is it on the back side where it will not be seen.

 

[jdinspector]

I would do something about it. See this article about Pyrolysis. http://www.chimneycricket.net/sitebuildercontent/sitebuilderfiles/pyrolysiscausesfires.pdf

I have been aware of pyrolysis, but wasn't aware that it was so prevalent until after I read that article. Clearance to combustibles is a serious issue that I see problems with almost daily. Professional HVAC contractors and masonry contractors seem to ignore the clearance requirements all of the time. Over the winter, I plan to take some thermal images of my chimney to see how hot it gets up high, and how hot the surrounding drywall, etc. gets. I think it will be surprising.

 

[jtp10181]

There is proper way to fix it unless you move the pipe or 2x6. Its is tested as an air space clearance. Any shield you build may or may not do any good. No agency or code book lists any such shield.

 

[RustyShackleford]

I can see where something like that could bug you. If you can't easily move the 2x6 I think I would try your shield idea just for peace of mind. You never know, they make that 2" clearance for a reason and over time the 2x6 can lower it's light off temp. Have you flelt the pipe temp during a good hot burn?

Yes, when the stove (my old stove, that is, a Dutchwest "large" catalytic, not the new
forthoming BK Princess) is really burning balls-out, I would characterize the outer
wall of the the Class A as "too hot to touch for very long": you can put your hand
on it without being burned - BUT you wouldn't want to leave it there very long -
whatever temperature that translates to ... This is a BIG burn, cat probe registering
1400 or above.

Is it possible to do a half moon cut on the 2 X 6 you only need5/8”.Is it on the back side where it will not be seen.

Not a half-bad idea, thanks. The "professional" did just such a thing on the loft-edge 2x10,
now that you mention it. It removes well under half the width of the 2x6, and I can always
brace it from behind, not that it's all that structural.

I have been aware of pyrolysis, but wasn’t aware that it was so prevalent until after I read that article.

Wow, ok. Sounds like I shouldn't just blow this off.

Any shield you build may or may not do any good. No agency or code book lists any such shield.

Maybe not in the context of cheating on the 2" clearance to a Class A chimney. But the shields
that are commonly employed to reduce clearances to a stove body work on a very similar
principle, do they not ?

 

[crazy_dan]

Just bash the class A in 5/8" that way yo do not need to cut the board.
Meh what kind of real advice do you want from a smart ass like me for free
Maybe Hank Hill fix it fer ya...
uh oh I am in a mood today %-P

I would cut the borad and get the right clearances.

 

[Sleepy]

I would do something about it. See this article about Pyrolysis. http://www.chimneycricket.net/sitebuildercontent/sitebuilderfiles/pyrolysiscausesfires.pdf

I have been aware of pyrolysis, but wasn't aware that it was so prevalent until after I read that article. Clearance to combustibles is a serious issue that I see problems with almost daily. Professional HVAC contractors and masonry contractors seem to ignore the clearance requirements all of the time. Over the winter, I plan to take some thermal images of my chimney to see how hot it gets up high, and how hot the surrounding drywall, etc. gets. I think it will be surprising.

Thanks for the link to this info. I am a heating contractor and have been in this business for 28 years. I am new to wood heat, but have worked with oil and gas all of my career. I have had excellent training and have always been very attentive to maintain proper clearance to combustibles. First I've ever heard of pyrolysis. I am going to print this and share it with my technicians.

 

[TomB]

Post a picture of the pipe and the clearances.

A metal "shield" will not be acceptable to protect the 2x6.

The picture would help, so we can see your problem.

Tb

 

[Fsappo]

From a code standpoint you would need to move the pipe or the 2x6. From a common sense standpoint I would put a strip of wonderboard spaced evenly between the two if it was in my own house

 

[RustyShackleford]

From a code standpoint you would need to move the pipe or the 2x6. From a common sense standpoint I would put a strip of wonderboard spaced evenly between the two if it was in my own house

Is wonderboard the masonry-like stuff you use behind tile ?

Maybe Hank Hill fix it fer ya…

I don't like the way he looks at my Nancy ...

 

[SolarAndWood]

The shield is not going to do you any favors if you are in a position where you need to make an insurance claim. I would leave the pre-existing condition in place or do what it takes to achieve the proper clearances.