Thanks for the advice. No I’ve not heard of “inversion layer”. I’ll plan on taking my vents through the roof. I was hoping the gases and smells would go out the ridge vent with the other attic gases or “hot air”. It probably wouldn’t work that way. I was trying to avoid penetrating the roof so I could go ahead and put the shingles on without having to worry about where to place the vent pipes. Thanks for the response.