Vermont Farmhouse - Venting Cooking Exhaust With Double Wall Chimney Pipe Through Standing Seam?

[LegendsCreekFarm]

I was here years ago and was able to successfully install an elaborate Central Boiler setup solely because of the help I received on this forum! I've got unique situation, and have spent dozens of hours trying to find a way to make this work, and I'm hoping to some more advice.

The kitchen in my home doesn't have a range exhaust vent, and it's causing a lot of problems with my Bluestar 48" range. I need to duct the exhaust outside, and therein lies the problem. The only possible way to duct the exhaust is into a small closet above the kitchen, and out the roof. I looked at bringing the pipe through a side wall, and the only way to do it would be ugly, and require a lot of 90 degree bends (I don't want to lose CFM).

I've called every roofer in VT, and 95% don't return my calls, but the few that do will not drill a hole through my standing seam. I was told by the standing seam installer who did the project before I owned the home that he could do the job, but would require reroofing the entire home. He claims that in order to do it properly I would need to destroy the panel I'm going through, and install a new panel with a precut hole for proper flashing, but then the colors won't match the rest of my roof due to fading (not going to happen).

Then I realized that you can buy those round roof jack bases with the rubber or silicone collar, and cut right through the standing seam, and then secure from the top of the roof using butyl and neoprene washers on roofing screws. This is how it's done for plumbing vent pipe, and I've seen photos of them also being used for wood stove chimneys.

My duct is going to be 10", and I will be installing an in line fan and not one built into a hood. The reason I am considering using the double wall pipe meant for high heat is because of the durability. It needs to withstand Vermont winters even though the pipe will only sit a few feet from the ridge. I don't want it getting torn off the house. I was told to install one of these, and I love the look of it, but I don't know if it's possible to install it the same way I would the rubber boot (because everyone has told me you need to rip up the standing seam to install them properly). Here is an example of what I wanted to install originally and would still love to if it's possible: https://www.famcomfg.com/product/bath-fan-kitchen-exhaust-roof-vent-with-extension-copper/

I am assuming this sort of vent won't work because the flange doesn't come with any way to properly flash it to standing seam around the hole I will have to cut in the roof, like a rubber roof boot does? Or is there a way I can properly flash it the same as I would with a rubber roof boot/aluminum flange using butyl and screws with neoprene washers?

If I cant do the copper vent that would sit flat to the roof as shown above, I was planning on coming straight up with 10" double wall chimney pipe, and then just using a standard bug proof cap on the top, so long as I can come through the standing seam with the rubber boot. I also have to properly secure the heavy pipe both inside and outside the house (I can use straps that attach to the seams to help, and also an ice breaker above it, even though it shouldn't be a problem as high on the pitch as it's going).

I really appreciate any help and advice I can get. I've been trying to do this for years, and really want to get it done. I am including a photos of what I had in mind just as an idea if I can't use the flat copper vent posted above. The in line fan would be somewhere above the kitchen and below the roof, and obviously I would be using real chimney pipe and not that junk shown in the photo.

Thanks in advance for any advice you can give!

 

[begreen]

Search on - kitchen exhaust vent for standing seam roof . There are lots of solutions. Copper might work, but I would be concerned about the dieletric reaction between disimilar metals unless the roof is also copper. If not, stainless would be a safer option.

When building this out, pay attention to making it cleanable. This may include adding a service door. Have a grease filter fitted in the range hood.

And be careful with the CFM. A powerful range hood fan can rob combustion air from stoves, furnaces or boilers. Be sure it has a variable speed option. A lot of times 150 cfm can be sufficient for daily cooking. It'll be quieter at that speed too.

 

[LegendsCreekFarm]

Search on - kitchen exhaust vent for standing seam roof . There are lots of solutions. Copper might work, but I would be concerned about the dieletric reaction between disimilar metals unless the roof is also copper. If not, stainless would be a safer option.

When building this out, pay attention to making it cleanable. This may include adding a service door. Have a grease filter fitted in the range hood.

And be careful with the CFM. A powerful range hood fan can rob combustion air from stoves, furnaces or boilers. Be sure it has a variable speed option. A lot of times 150 cfm can be sufficient for daily cooking. It'll be quieter at that speed too.

Thanks for taking the time to chime in @begreen ! I hadn't even considered reaction between the metals, though the copper option I posted would sit on top of the painted surface of the roof. They do also make it in stainless though, and I am not sure copper is even a smart idea if I went that route due how soft it is.

The hood itself will have grease traps, and in past properties I've always made the entire run serviceable for cleaning as needed.

As far as CFM, my range is commercial, and puts out 10,000 BTU per burner, so a much higher CFM is needed. That said, the fan will be on an adjustable switch with speed control. The house s also old, and not well insulated, so combustion air won't be an issue, but we typically open a window a crack whenever doing heavy cooking.

So do you not think it would work the way I asked about above where I could use double wall chimney pipe as an alternative so that I can avoid using the flat looking copper style one shown above? I think the chimney pipe would be much more secure in Vermont, and allow smoke to get out during heavy snow. The double wall pipe also can be used with those roof jack bases (like the Fantech one above), which are made to go through all roofing material, and I could drill the 10" hole right through the standing seam and seal it. I don't have that option with the other flat style vent and have no idea how I could install that on existing standing seam without having to tear my entire roof apart.

Thanks again

 

[begreen]

Class A chimney pipe would probably work and there are good flashing systems made for standing seam roofs. This is ICC Excel pipe and flashing. It gets notched on the bottom to accomodate the seams.

 

[LegendsCreekFarm]

I've never seen that flashing before. I really appreciate you posting it for me. I've asked on several roofing forums and haven't been able to get any help. I will check it out. I think class A pipe is probably a safer bet just because of where I live. It's overkill for cooking smoke, but I need something strong. Thanks!

 

[begreen]

One more shot. The top end of the flashing gets inserted under the metal roofing. The bottom end sits on top of the metal.

 

[LegendsCreekFarm]

One more shot. The top end of the flashing gets inserted under the metal roofing. The bottom end sits on top of the metal.

View attachment 331383

My seams are 18" apart, so there's a chance I won't even need to go over one of them. Would this same flashing still be used if that's the case? Posting a photo of my roof.

 

[begreen]

If the flashing fits between the seams then a regular chimney pipe flashing may work. Same procedure, the top goes under the roofing and the bottom overlaps it.

Edit: Just looked at DuraVent flashing and it's 20" wide for 6" chimney and 30" wide for 8".

 

[LegendsCreekFarm]

If the flashing fits between the seams then a regular chimney pipe flashing may work. Same procedure, the top goes under the roofing and the bottom overlaps it.

Edit: Just looked at DuraVent flashing and it's 20" wide for 6" chimney and 30" wide for 8".

I was looking at these as an option. They say that it's silicone and made for high temp, so I assumed it would work with class a pipe meant for venting stoves. This particular one posted below would fit between my seams but I'm not sure if it's meant for class a pipe?

I may not have a choice but to go through a seam anyway if the location where I bring the pipe up from the kitchen doesn't allow me any wiggle room to avoid it. I haven't determined that yet.

 

[begreen]

I'm not a fan of them for big pipe. They seem leak worthy over time, even if just a weeper. Also, they need a bajillion screws to hold down. That's too many holes for my liking.