Chimney 2" Clearance to Combustibles

[jatoxico]

At the risk of incurring the wrath of the code Nazi's I'm looking for opinions. My brick chimney is 3 bricks wide by 2.5 bricks deep and was added probably sometime in the late 80's (house built 60's). Bricks are 8x3.5". Steel uninsulated liner runs in the clay tile.

As (I hope) you can tell the clay tile was placed offset in the brick structure as far as possible to the outer brick (away from the house). I always calculated that the offset, which is a full brick length gave about a 4.5 - 5" gap (including mortar) from the outside of the liner to the brick that actually touches the wood structure which exceeds the 2" requirement. Is that the right way to look at it? Missing something?

 

[bholler]

At the risk of incurring the wrath of the code Nazi's I'm looking for opinions. My brick chimney is 3 bricks wide by 2.5 bricks deep and was added probably sometime in the late 80's (house built 60's). Bricks are 8x3.5". Steel uninsulated liner runs in the clay tile.

As (I hope) you can tell the clay tile was placed offset in the brick structure as far as possible to the outer brick (away from the house). I always calculated that the offset, which is a full brick length gave about a 4.5 - 5" gap (including mortar) from the outside of the liner to the brick that actually touches the wood structure which exceeds the 2" requirement. Is that the right way to look at it? Missing something?
View attachment 237486

Your brick touches the wood structure so you have zero clearance where you should have 1". It is not to code without an insulated liner.

 

[jatoxico]

Your brick touches the wood structure so you have zero clearance where you should have 1". It is not to code without an insulated liner.

So no brick can touch the structure at all?

 

[bholler]

So no brick can touch the structure at all?

Nope all that can touch the brick is trim on the corners and non combustibles.

 

[jatoxico]

Nope all that can touch the brick is trim on the corners and non combustibles.

So where does the 2" rule come in or did I make that up in my head?

 

[bholler]

So where does the 2" rule come in or did I make that up in my head?

If it is an interior chimney it needs 2"

 

[jatoxico]

There has to be some distance that would be acceptable. What if it was two feet from tile to the brick nearest the home?

 

[bholler]

There has to be some distance that would be acceptable. What if it was two feet from tile to the brick nearest the home?

Not by code no. There should be I agree but there isnt

 

[jatoxico]

Not by code no. There should be I agree but there isnt

So this concept if you will comes up all the time here. What happens when for whatever reason the situation is not addressed by the written code, does an inspector have the authority to sign off in such circumstances.

And the code not withstanding, a roughly 5" air gap seems pretty OK to me. I can't get the interior brick that has much less gap than that (albeit with no combustibles near) above about 150 deg and that's 10" off the top of the vent.

 

[bholler]

So this concept if you will comes up all the time here. What happens when for whatever reason the situation is not addressed by the written code, does an inspector have the authority to sign off in such circumstances.

And the code not withstanding, a roughly 5" air gap seems pretty OK to me. I can't get the interior brick that has much less gap than that (albeit with no combustibles near) above about 150 deg and that's 10" off the top of the vent.

If they give you a waiver yes simply saying it is ok without giving you a written waiver leaves it open.

And yes if there was an internal 5" gap I would say it is ok. But if there are even just areas where that gap is filled with masonry it is not ok and you have no way to know that.

 

[jatoxico]

But if there are even just areas where that gap is filled with masonry it is not ok and you have no way to know that.

Yes I understand that.

 

[fire_man]

There has to be some distance that would be acceptable. What if it was two feet from tile to the brick nearest the home?

I have this exact situation. It's a 36" wide external chimney with the clay liner practically touching the outside brick.
I insulated the SS Liner.

 

[jatoxico]

I have this exact situation. It's a 36" wide external chimney with the clay liner practically touching the outside brick.
I insulated the SS Liner.

No argument that it's better to be insulated.