Between the House and Chimney ....

[SOH]

Hello all!

As I stare down the barrel of another Michigan winter, I'm trying to keep this project moving! My new discovery is this: My house is sheeted with 3/4" pine boards -- not uncommon for 1923. At some point it was wrapped in felt paper and asphalt siding. Subsequent to that, the chimney was built. There is about a 1" space between the sheeting and the chimney (16x16, clay lined 6x6), which I understand to be a good thing. Here's the question: Can I run house wrap behind the chimney (over the sheeting) and then cover it with 1/4" Durock or similar? I would then use a non-combustible trim or backer rod and the appropriate caulk. I'm trying to establish a weather-tight air space behind the chimney, as the boards are gapped and there is plenty of wind and water coming in, especially around the existing "thimble" which can be seen in the other photo. Perhaps the answer is to cut out the sheeting from behind the chimney and replace it with something more appropriate that is still 3/4"? My ultimate goal is to improve the integrity of the sheeting and replace the vinyl siding, likely within a couple of years. Ideas?

Many Thanks!

 

[bholler]

no just trim it out next to the chimney leave that space. Is the chimney lined?

 

[SOH]

no just trim it out next to the chimney leave that space. Is the chimney lined?

The chimney has a clay liner but I've been advised to add a stainless steel liner (getting someone out for a second opinion as the first guy didn't even look at the existing system). I don't want to fill the space behind the chimney, but I would like to have something other than that crumbling asphalt covering that pine so that if water does sneak in there it will at least drain down. Can I use a combustible (wood) to trim out the outside chimney edges? Leave an expansion joint and use heat-resistant caulk? Thanks as always!

 

[Woodfarmer1]

You should have 2" of irspace between chimney and combustibles.

 

[bholler]

Can I use a combustible (wood) to trim out the outside chimney edges?

yes you can and yes you could pull that asphalt off and replace it with something else behind there

You should have 2" of irspace between chimney and combustibles.

No for an exterior chimney it is only 1" and you can have combustible trim at the edges

If you had it lined with an insulated liner you would not need anything

 

[SOH]

You should have 2" of irspace between chimney and combustibles.

Had I been the builder, I would have done that. I understand the code, but what about existing structures? I don't want to tear down the chimney and start over, especially if I can add a thin non-combustible material between the house and chimney.

 

[SOH]

No for an exterior chimney it is only 1" and you can have combustible trim at the edges

good to know

 

[bholler]

Had I been the builder, I would have done that. I understand the code, but what about existing structures? I don't want to tear down the chimney and start over, especially if I can add a thin non-combustible material between the house and chimney.

You only need 1" no need for a non combustible

 

[SOH]

You only need 1" no need for a non combustible

Thanks very much, everyone! This has been very helpful.

 

[stevemd]

yes you can and yes you could pull that asphalt off and replace it with something else behind there


No for an exterior chimney it is only 1" and you can have combustible trim at the edges

If you had it lined with an insulated liner you would not need anything

bholler I have a straight 7x7 inch clay lined flue.Do you know if I can get a 6inch liner in it.

 

[BrotherBart]

A six inch corrugated liner is around 6.25" outside diameter. Check and see if you have a paint can, that is usually about that diameter, and see if you can lower it all the way down in the chimney.

 

[stevemd]

A six inch corrugated liner liner is around 6.25" outside diameter. Check and see if you have a paint can, that is usually about that diameter, and see if you can lower it all the way down in the chimney.

Great tip I will try that thanks

 

[zig]

Had I been the builder, I would have done that. I understand the code, but what about existing structures? I don't want to tear down the chimney and start over, especially if I can add a thin non-combustible material between the house and chimney.

Shot in the dark but what about steel siding?

 

[bholler]

Shot in the dark but what about steel siding?

No code calls for 1" air space which is there. Adding something even if it is non combustible will not be to code.

bholler I have a straight 7x7 inch clay lined flue.Do you know if I can get a 6inch liner in it.

maybe maybe not but you will not get an insulated one in there that is why we break out the old tiles

 

[Ashful]

A six inch corrugated liner liner is around 6.25" outside diameter. Check and see if you have a paint can, that is usually about that diameter, and see if you can lower it all the way down in the chimney.

Very cool tip.

 

[SOH]

A six inch corrugated liner liner is around 6.25" outside diameter. Check and see if you have a paint can, that is usually about that diameter, and see if you can lower it all the way down in the chimney.

Brilliant tip. Thanks.