Sealing the stack

[eustis22]

I kind of hacked out a rough circle in my metal roof for the stack so there are gaps around the stack that I would like to seal to prevent snowmelt/water from leaking down the stack. Does anyone have any ideas about what to use? I tried furnace cement but it turned out to be water soluable. The roof is somewhat corrugated so regular flashing will not work.

[whity]

We use copper based RTV. Has a 1200 degree melting point.

[bigschuss]

I kind of hacked out a rough circle in my metal roof for the stack so there are gaps around the stack that I would like to seal to prevent snowmelt/water from leaking down the stack. Does anyone have any ideas about what to use? I tried furnace cement but it turned out to be water soluable. The roof is somewhat corrugated so regular flashing will not work.

Did you put your chimney up through the metal roof and then into flashing? Or did you just go up through the metal roof into blue sky? If the latter, I would use something like this:

https://www.fastenersplus.com/6-Roofjack-Square-Silicone-Pipe-Flashing-Boot-Red?gclid=EAIaIQobChMIuZT50IGU4AIVVuDICh20uALOEAQY ASABEgKB5PD_BwE

I am going to be going through a corrugated metal roof in a new barn a built and am going to try just this product. The base is malleable and conforms to the profile of your corrugated roof.

[whity]

Did you put your chimney up through the metal roof and then into flashing? Or did you just go up through the metal roof into blue sky? If the latter, I would use something like this:

https://www.fastenersplus.com/6-Roofjack-Square-Silicone-Pipe-Flashing-Boot-Red?gclid=EAIaIQobChMIuZT50IGU4AIVVuDICh20uALOEAQY ASABEgKB5PD_BwE

I am going to be going through a corrugated metal roof in a new barn a built and am going to try just this product. The base is malleable and conforms to the profile of your corrugated roof.

Yes we went through a corrugated metal roof. But had a stainless roof jack and rain collar. Sealed the collar with the RTV copper. I looked at the specs on this jack you put the link up for. Is 500 degree going to cut it? The max temp is only rated for 500f

[whity]

I know Bascoms has already made stainless roof jacks available. For under $300

[bigschuss]

Yes we went through a corrugated metal roof. But had a stainless roof jack and rain collar. Sealed the collar with the RTV copper. I looked at the specs on this jack you put the link up for. Is 500 degree going to cut it? The max temp is only rated for 500f

I did a quick search for that link yesterday. If you look around you'll see other variations and other companies with different temp ratings. Some have a round base and others a square base. 500F might be the upper limit though on these silicone roof flashing products.

[whity]

My 2 cents is Invest in the good roof jack. $300 in cheaper then loosing your sugar shack.

[TapTapTap]

I don't worry about the slight gap. Rain and snow are a minimum. It melts and dries just like steam condensate.

[eustis22]

>Or did you just go up through the metal roof into blue sky?

Into the wild blue yonder. My concern is the facilitating of rust on the stack.

>Copper RTV

I was wondering if something like JB Weld would be applicable. I think I've had readings of 700 degrees on my stack at times.

Thanks for the quick responses.

[whity]

>Or did you just go up through the metal roof into blue sky?

Into the wild blue yonder. My concern is the facilitating of rust on the stack.
Are you using mild steel stack or stainless. Painted steel will rust once the heat gets to it and moisture sets on it.

>Copper RTV

I was wondering if something like JB Weld would be applicable. I think I've had readings of 700 degrees on my stack at times.



Thanks for the quick responses.

I don't know what the melting point is of JB Weld. If you can get a rain collar on and seal it with high temp silicone would be your best bet.

[bill m]

A proper roof jack with a storm collar is the only way to go. Rain coming in will eventually rust out the arch. You will then need to replace or re-tin the arch and reinsulate or re-brick

[n8hutch]

I wish I had taken pictures when we installed the roof jack on my sugar house, because it's kinda hard to explain, it's not a corrugated jack, the piece of roofing above the jack comes down over it until it is flush with the top side, the piece of steel roofing below the jack comes up under the jack until it is under the upper piece, then I used a short cover piece of roofing to cover the roof jack, you basically cant see any part of the roof jack, save the vertical piece that the storm collar sits on . It has worked very good this way. Wish I had some pictures because I dont think that I explained it that well.

[bigschuss]

If I'm understanding the OP correctly, I think the issue is that a normal roof jack will not work with corrugated metal roof, if you simply hack a hole in the metal. You can certainly use a standard jack with corrugated metal roof if you plan it properly and flash it properly during the build. But after the fact a standard jack with a storm collar will do no good on a corrugated metal roof with a hole in it, unless you get very creative in fabricating some kind of flashing that conforms to the contours of the roof. Here's a few pics of different products that conform to the corrugated roof. The 3rd pic shows a standard roof jack with some customization that also uses the ridge cap to flash the top of the jack. The last pic shows a standard jack that looks also to have been modified with some cuts and metal work to conform to the roof's profile.

Just a few ideas and food for thought for the OP. Good luck!

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[Super Sapper]

For ours we installed the roof jack on top of the steel. We ran a piece of flat steel just wider than the roof jack and the same color as the roof under the ridge cap and over the top edge of the roof jack. Most places make a foam strip that is formed to fit under the lower edge of the roof jack to keep our bugs.

[maple flats]

Mine has no roof jack. Mine is also just cut thru the steel roofing, and then I have a rain collar on it and slid down against the roof ridge cap. I hardly ever get any rain in or snow. The rain collar is tight against the stack with no sealant. My stack has been like this for 17 seasons, this is #18. The first 3 were with a 7" stack on a 2x6 and the rest have been a 12" stack on my 3x8. It works fine.

[Chickenman]

I would personally use the regular roof jack then seal the edges to the roof deck with EPDM roofing seam or flashing strips. The stuff stretches well to conform to the ribs on the roofing and is supper sticky so it will bond well to clean metal.