Installing a Plumbing Boot on a Metal Roof
#8
I will need this knowledge later this summer.    I looked at stuff today.  This video

https://www.youtube.com/watch?v=eidzG74VT5U

he is simply pressing the boot down on top of the roof, albeit with sealant.  That seems sketchy.  He cuts the hole in the metal with a chisel.  Is that normally how it's done?  I expect that you put the pipe through the ridge because it helps keep the water out?

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#9
You don't always have a choice where the pipe ends up on the roof. The metal roof can be the flashing, so I think installing a boot like he did acceptable to me. I think he did a good job.
What I would do differently, is make sure there is a 1" gap between the type B vent and combustible material such as a rafter or wood deck material. Roofers sometimes don't follow this rule and later when an inspection is done, someone else has to correct it. The other thing I do is install a collar over the pipe. I seal the boot to the pipe, then slip a collar over that. The collar protects the sealant and the connection between the boot and pipe from the sun and weather.
I start the cut with a flat screwdriver and hammer and use left hand cutters/snips to cut the hole. His looked fine though.

The only other questionable thing if you get down to the nitty gritty of codes- You need a 1" gap to any combustible material. Rubber, silicon rubber, silicon sealant is combustible. But to be honest, no one ever says anything about this part- just keep the pipe an inch away from the wood or combustible material.
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#10
Wouldn’t last long here in the sun. Here, vent pipes are close to ridge and therefore the leading edge can be overlapped by the ridge covering. That thing will need periodic maintenance.
I have that same pattern roof on my house and I use a jigsaw to make any cuts. I can cut a hole like he did in less than a minute.
VH07V  
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#11
(07-08-2020, 04:02 PM)daddo Wrote: The only other questionable thing if you get down to the nitty gritty of codes- You need a 1" gap to any combustible material. Rubber, silicon rubber, silicon sealant is combustible. But to be honest, no one ever says anything about this part- just keep the pipe an inch away from the wood or combustible material.

This will be for a vent stack for plumbing, so if it were on fire, the fact that the boot is combustible wouldn't matter. 
Smile

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#12
That video is spot on with how it's done. Metal roofs usually galvalum are becoming the most popular roofing to do here in Texas. They keep the house cooler than asphalt and last way longer and just laugh at hail. Those epdm boots hold up just fine in the heat and sun here. They rarely ever leak and if it does it's due to installation. 
 
          There are different ones available and you can make a diverter to go over the uphill side to act like a shingle effect but it's not needed. 


              I would like to do Galvalum on our roof but it does need routine cleaning because we have lots of oak trees and they will get the roof dirty and reduce the heat reflecting ability due to the dark dirt from the tree sap. It's also much lighter than other roofing materials.
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#13
Most people don’t recognize a metal work is weatherproof not watertight. They’re all held together with caulk and screws. You can’t avoid having to flash over a rib. Lookup deck time flashing boots. They have butyl tape along the bottom edge and usually a lead metal band at the edge on top of the rubber boot. They lead helps the boot flange conform to the panel profile. After you install the boot you still should caulk the edge. Especially at the rib. Now here is a little extra protection. Before you slid the boot on run a bead of your caulk around the roof opening. It will be maybe 3/8” hi. That way if water does run under the boot it most likely won’t run into the deck opening.
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#14
(07-11-2020, 06:35 PM)whatline Wrote: . Before you slid the boot on run a bead of your caulk around the roof opening. It will be maybe 3/8” hi. That way if water does run under the boot it most likely won’t run into the deck opening.

I was planning on doing that

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