Running vents outside in cold climate...
My new (to me) house was built without bathroom vents (yuck) and the dryer vent currently exhausts right under a deck.
This means I'm going to have to run a bathroom vent and a dryer vent under the deck out to clear space.
I'm in British Columbia, so the rules may vary somewhat, but I know the vents have to be insulated when they enter the cold space outside.
I can get the black sock- insulation and black plastic sleeve stuff, but I'm sure it's not outdoor rated, and the deck is not waterproof, so rain and melting snow will drip on it. Galvanised could eventually rust, which is my other concern.
I had considered perhaps wrapping the pipe in suitable insulation, (I assume rockwool for the drier vent) and sleeving it with a larger diameter pipe - probably UPVC sewer pipe. It would be an air and moisture barrier.
The only other alternative I can think of is double walled external fireplace piping, but being stainless I suspect it's incredibly expensive.