My MEP803A permanent install

Well guys you got me thinking and I think I will give it a shot and maybe I can seal up that leak in the roof with the addition of a flex pipe.. I found a 12" 1-1/4 NPT flex pipe at MSC for $48 my cost (made in China of course), I ordered 2 as I will be installing another unit this summer in another barn. I will try and follow up after install.

https://www.mscdirect.com/product/details/80585458

They do have an 18" for a bit more.

If you google "Tent Stove Jack" you will get several hits for solutions that should work with your roof penetration exhaust.

Here is one I ran across that would work nicely, although a bit pricey. There are probably others that are less expensive if you do some searching.

The problem I ran into is the corrugations in the roofing metal do not allow me to use something like this. I am sure there are specialty ones available and I will look around more.. If I could get that to fit my roof it would be worth the money..

I ran into the same issue with my metal barn roof where the service entrance mast head was leaking water as the former owner had jerry-rigged it with tar that had cracked over time. The mast head exited right next to one of the metal roof seam overlaps. I found a mast head roof penetration kit that was designed to solve that problem. It used a very flexible aluminum surround bezel about 3/4" wide at the edge of the rubber boot that you can easily bend and form to follow the contours of the metal roofing seam. It came with self tapping screws & washers that you were to then use to screw through the aluminum bezel from the top into metal roof and seal with silicone sealant under the flange area to make it 100% water tight. Since I replaced it, never has leaked a drop with rain, snow or ice. The only catch is you would need to find one in that style with the fire/heat retardant rubber boot. You might be able to devise one using a tent stove jack & using thin strap-like material in aluminum, brass or copper to conform the edges of the boot to follow the roof contour if its not too radical a contour and then screw & seal it in place.

Edit: This is what I used on my roof electrical service entrance mast head penetration. Its rated for 212F continuous/ 275 intermittent. Not sure what your exhaust pipe temp would be at that distance. After I installed it, I painted it to match roof and for added UV resistance for the rubber boot and it turned out quite nice. In the beginning I wasn't too sure about it as it seemed a bit flimsy with the cut-to-fit circles for various diameter pipe and with the seam that clips it together, however after it was all screwed down, sealed and buttoned up it seemed quite stable and tight.

I did see those after Chainbreakers post and went looking. I will review the placement of my pipe and might revisit this exhaust installation in its entirety.. Thank you for all your suggestions..

I installed this flexible pipe section to my exhaust over the weekend and I was a bit surprised. I use to have a little rattle to the rain cap anytime the set was running. It wasn't bad but a little annoying. That is gone now so I guess it was well worth the $50 and 30 minutes of my time.. I put another big blob of this fire rated caulking around the pipe on the underside of the roof and let it cure over night. I ran the unit to temp on Sunday and it seemed to hold.. Not sure long term how it will do but time will tell.. Here is the flex pipe I got. They make a 12" and 18". I went with the 12 and its plenty long enough.

https://www.mscdirect.com/product/details/80585458

I have a piece of flex, a couple 45 degree elbows, and a turn to go out my metal roof. I used fire caulk both sides first and then some high temp silicone over top of that after running the unit. No leaks yet. Been like that almost 2 years.