I am in a quandary

[begreen]

This topic has come up in the past. One question is whether the silicone boot is UL approved and accepted by the chimney pipe mfg. for this application. You may find this thread helpful.
https://www.hearth.com/talk/threads/silicone-roof-jack-with-class-a-chimney.43014/

 

[webby3650]

Not familiar with dektite. What's wrong with it? I assume it's the type where there's a metal flashing, and you cut the boot out to fit the pipe diameter?

I’m not familiar with that particular flashing. But if it’s a rubber boot then I’m not a fan. It’s an inferior product to a metal flashing that installed properly. We see them fail all the time..

 

[jetsam]

I’m not familiar with that particular flashing. But if it’s a rubber boot then I’m not a fan. It’s an inferior product to a metal flashing that installed properly. We see them fail all the time..

With an all-metal flashing, what provides the watertight seal? I'd think RTV silicone would be just as bad. Brazing?

 

[webby3650]

With an all-metal flashing, what provides the watertight seal? I'd think RTV silicone would be just as bad. Brazing?

It tucks under the metal at the top similar to a shingle roof flashing. I’m fact a regular flashing can be modified to work the same way.
Then it has a storm collar just like a standard flashing. It’s a permanent installation that doesn’t rely on sealant, offers support, won’t break down over time in uv rays.

 

[Ludlow]

The boot should be high temp silicone, not rubber and probably red. I used red high temp silicone on the joints of my ZC gas fireplace vent and they are like new after 16 years. Let me tell you that pipe gets so hot your finger will stick to it like sausages in a dry frying pan. Even so, galvalume flashing is better.