Venting a furnace through a steel building pole barn

[Mike Heidrick]

Soon I will need to vent my furnace through my pole barn. Is there any info on the net ( video or write ups) on how to do this correctly with a metal building that has ribs (think menards/morton type metal building). I have never cut a hole in a building before. Furnace is a NG boiler.

[Marty Tippin]

You need this http://www.oatey.com/products/flashi...roof-flashings

Along with some silicone caulk. Works like a charm.

[William C Rogers]

Mine are located in the back of the shop. They vented mine out the back instead of the roof. I don't know if you have that option. They used a rubber flange. I can see if there is a name on the flange and take pictures if this is an option for you.

[Mike Heidrick]

That would be awesome William!! Mine will vent in the front of the building but I need to do what I need to do.

Marty I will check your link too!

Thank you guys and anyone else who can pass on some lernin to me.

[Marty Tippin]

I wouldn't vent through the side of your building if you can help it, especially not at the front of the building. Going through the roof is not difficult; just use the flashing I provided a link to and be careful where you cut the hole to make sure it's in the right location. Your vent stack will need to protrude above the roof line by some amount, likely dictated by local code.

[William C Rogers]

I wouldn't vent through the side of your building if you can help it, especially not at the front of the building. Going through the roof is not difficult; just use the flashing I provided a link to and be careful where you cut the hole to make sure it's in the right location. Your vent stack will need to protrude above the roof line by some amount, likely dictated by local code.

Marty, I wouldn't vent through the front, but what is the reason you wouldn't vent through the back? Having two other buildings with venting in the roof, they will eventually leak as the rubber breaks down.

[Mark Bolton]

If you opt to go through the roof and simply poke a hole and use one of the rubber boots posted above my only advice would be to skip the silicone and opt for butyl tape. And use a lot of screws. Most metal manufacturers will recommend spacing your screws in the aluminum flange of those boots very close. Like closer than 1" spacing. The flanges are very soft and spacing your screws any distance apart will allow for a leak between the screws. When you screw tightly you can very easily squeeze all the caulk out from under the boot flange which will leave you basically zero protection. Butyl tape will remain plastic for decades. If you must use caulk I would never use silicone as it fails too quickly. Id go with something like Quad and run a very thick bead. Run your screws in barely snug. Let the caulk set up for a day. Then go back and torque them down. The Quad will form a rubber seal with some thickness and letting it cure will make sure you dont squeeze it all out from under the boot.

Roof penetrations are one of the main reasons I despise metal roofs but they are hugely popular here (I am putting a nightmare one on at the moment). But with a steel building you have no other option. There is simply no easy way to deal with a roof penetration without trusting your water-tightness to a bead of caulk and thats a sucky option.

When I do them I flash them in differently but it involves field bending material and having extra roofing panel to make a lap thats water tight without a bead of caulk.

[Larry Edgerton]

I wouldn't vent through the side of your building if you can help it, especially not at the front of the building. Going through the roof is not difficult; just use the flashing I provided a link to and be careful where you cut the hole to make sure it's in the right location. Your vent stack will need to protrude above the roof line by some amount, likely dictated by local code.

Why? If you have an efficient power vent furnace/boiler they are made to vent out the side and the termination is not at all unsightly. Better than a hole in the roof that will at some point leak.