Class A Chimney touches OSB sheet when exiting through the roof

[Bummer]

Hello-

I recently had a 6" class A chimney installed straight up through the ceiling and then the roof. The pipe is clearing the rafter by 2" but is in direct contact to the OSB sheet under the metal roof. Is that cause for concern and should I contact the contractor to cut away some more of the OSB?

Thanks,
Chris

 

[Sodbuster]

Yes, I believe depending on the brand that is needs a 2" -3" clearance to a combustible. And if he won't do it or listen, call the inspector.

 

[bholler]

Hello-

I recently had a 6" class A chimney installed straight up through the ceiling and then the roof. The pipe is clearing the rafter by 2" but is in direct contact to the OSB sheet under the metal roof. Is that cause for concern and should I contact the contractor to cut away some more of the OSB?

Thanks,
Chris

Yes it needs cut away without question.

 

[Bummer]

I think I would sleep better at night with some added clearance... Some of the screws from the silicone boot are pretty close to the pipe (it's a DuraVent brand: (broken link removed to http://www.duravent.com/Product.aspx?hProduct=1)) meaning in some areas I cannot achieve a 2" clearance. But at least getting 3/4-1" would be better than direct contact...

 

[Highbeam]

This is not a "close enough" situation. My duravent class A required 2". Not 1", not 3/4", not mostly 2", 2" MINIMUM. I made an installer return and do it right. That was the last time I trusted a certified installer that was members of all sorts of organizations to know what they were doing.

 

[Squisher]

Yah I'm not following why clearances can't be achieved? If it's 2" chimney 2" is what it needs. Anything less is not code compliant and shouldn't/wouldn't pass inspection.

 

[Squisher]

If it's 2" clearance all of the certified components that the manufacturer recommends be used will allow for proper clearances.

 

[Squisher]

In canada we can't use those rubber boots unless it was allowed by the manufacturer and a certified component which I don't think exists? It's my understanding that most of the rubber boots used are meant for plumbing stacks and up here isn't proper.

I am not familiar with how this is treated in the USA.

 

[begreen]

I think I would sleep better at night with some added clearance... Some of the screws from the silicone boot are pretty close to the pipe (it's a DuraVent brand: (broken link removed to http://www.duravent.com/Product.aspx?hProduct=1)) meaning in some areas I cannot achieve a 2" clearance. But at least getting 3/4-1" would be better than direct contact...

This is not an issue with the recommended Excel flashing.

 

[Squisher]

Excel flashing?

 

[begreen]

Excel metal roof flashing


(broken link removed)

http://icc-chimney.com/en/excel

 

[Bummer]

(broken link removed to https://www.duravent.com/docs/product/L150_W.pdf)

from page 9...

5. Cut Roof Opening: Cut an opening in the roof directly above the opening below, and at least 4” larger than the chimney’s outside diameter to provide at least a 2” clearance all around the chimney. The chimney must be centered within this opening and maintain the 2” clearance to combustibles

 

[Squisher]

Ok. Threw me a bit icc excel is 1" clearance chimney up here. So I assumed their flashing may not give proper clearances. But it must just depend on how big of a hole is cut/placement. Duravent doesn't make their own flashing? Or the excel is just a superior product?

 

[Squisher]

(broken link removed to https://www.duravent.com/docs/product/L150_W.pdf)

from page 9...

5. Cut Roof Opening: Cut an opening in the roof directly above the opening below, and at least 4” larger than the chimney’s outside diameter to provide at least a 2” clearance all around the chimney. The chimney must be centered within this opening and maintain the 2” clearance to combustibles

No manufacturer is going to have instructions/products ok'd with their chimney that do not allow proper clearances. If the 2" isn't there, the installer screwed up.

 

[begreen]

Ok. Threw me a bit icc excel is 1" clearance chimney up here. So I assumed their flashing may not give proper clearances. Duravent doesn't make their own flashing? Or the excel is just a superior product?

The Excel flashing is designed for metal roofing. I believe it's wide enough to provide the 2" clearance.

 

[Highbeam]

Duravent doesn't make their own flashing?

I know that they do for regular flat roofs. Like composition flat but pitched.

 

[Squisher]

Nice. There is such a myriad of chimneys and components. I'm finding it difficult to always identify everything as a sweep, obviously no issue if labels are still present but often they don't last long. I'm trying to make a point of identifying everything I'm working on not always easy with factory built chimney.

 

[Squisher]

I know that they do for regular flat roofs. Like composition flat but pitched.

Thanks I know that they do. I was just hoping for some clarification from Begreen on the recommendation for excel.

I am here to learn.

 

[Bummer]

Pretty sure it's fair to say my installer didn't know what the code was. He knew to maintain 2" to the rafter but must have thought that didn't apply to the roof OSB sheets. Logically speaking it does make sense to me that you need more clearance to framing running in parallel than a thin sheet of OSB that is exposed to the cold outside air.

I'll cut the sheet back to 2" where possible and will remain in violation of manufacture recommendation in the one area the screws protrude closer to the pipe than that. Short of completely redoing the roof install I don't see any other option than to compromise...

 

[begreen]

Thanks I know that they do. I was just hoping for some clarification from Begreen on the recommendation for excel.

I am here to learn.

I don't know of another cone style specifically made for metal roofs, but there may be another. @webby3650 has more experience than I with various installs using this product. There are several past posts on the Excel flashing that show installation, etc. with chimney other than Excel.

 

[bholler]

Pretty sure it's fair to say my installer didn't know what the code was. He knew to maintain 2" to the rafter but must have thought that didn't apply to the roof OSB sheets. Logically speaking it does make sense to me that you need more clearance to framing running in parallel than a thin sheet of OSB that is exposed to the cold outside air.

I'll cut the sheet back to 2" where possible and will remain in violation of manufacture recommendation in the one area the screws protrude closer to the pipe than that. Short of completely redoing the roof install I don't see any other option than to compromise...

This is not an area to compromise call them back and make them fix it. If they need to redo the roof so be it. They screwed up.

 

[Highbeam]

This is not an area to compromise call them back and make them fix it. If they need to redo the roof so be it. They screwed up.

I agree and it's not just a manufacturer's recommendation, it's a requirement for the installation. Your inspector missed it which is not uncommon but the inspector takes no liability. If the installer can get 2" clearance from the rafter then they can trim back the sheeting to the rafter for the 2" clearance as well. In my case, they had to slightly relocate the ceiling support box to gain 2" clearance from the rafter.

The sheathing being cold is not the answer. My firewood is ice cold seconds before it bursts into flames in the stove!

 

[bholler]

I agree and it's not just a manufacturer's recommendation, it's a requirement for the installation. Your inspector missed it which is not uncommon but the inspector takes no liability. If the installer can get 2" clearance from the rafter then they can trim back the sheeting to the rafter for the 2" clearance as well. In my case, they had to slightly relocate the ceiling support box to gain 2" clearance from the rafter.

The sheathing being cold is not the answer. My firewood is ice cold seconds before it bursts into flames in the stove!

Yes there are even times we need to relocate framing to get clearances. But it needs done no questions asked

 

[Bummer]

The sheathing being cold is not the answer. My firewood is ice cold seconds before it bursts into flames in the stove!

HAHA

Thanks guys for your support. I will reach out to the contractor today. Hopefully I will have an operational chimney some time this winter

 

[webby3650]

Pretty sure it's fair to say my installer didn't know what the code was. He knew to maintain 2" to the rafter but must have thought that didn't apply to the roof OSB sheets. Logically speaking it does make sense to me that you need more clearance to framing running in parallel than a thin sheet of OSB that is exposed to the cold outside air.

I'll cut the sheet back to 2" where possible and will remain in violation of manufacture recommendation in the one area the screws protrude closer to the pipe than that. Short of completely redoing the roof install I don't see any other option than to compromise...

If he left the osb within 2” of the pipe He must
Just not care. There’s multiple was of ensuring proper clearance is maintained, not gonna get into that. He didn’t do it properly, call him back.