Originally Posted by dthornton
I have two bathrooms back to back on the second floor. As part of remodeling, I have put bathroom vents in the ceilings. The roof is maybe 3 feet or so above the vents. I was planning on getting ducts/vents to route these through the roof, but upon researching it I've found that some professionals do not recommend this due to the possibility of leaks if not installed just right. With a fear of heights anyway,
I'm not about to attempt to get up on the roof and attempt this myself, so that would mean paying a "professional". I've decided to vent through the end wall (only about 4' or 5' from the vent boxes in the ceiling). For aesthetic reasons, I would prefer to not have 2 vents coming through the wall - this is an 1890 house with the original wood siding.
1. Can I run both ducts (4") into one vent through the wall? 2 . Are there any exterior vents that wouldn't visibly stick out like those dryer-vent hoods do? Thanks!
Two pipes into a single vent will increase back pressure so your fans may not live up to their posted CFM.
For bathrooms, 8 air changes per hours are recommended so a bathroom 8' H x 5' W x 7' L is 280 cu ft, 8/hr would be 2240 cu ft in 60 minutes would be 37 CFM.
The eyes of passersby probably will not be drawn to two vents on the side of the house.
I've installed both kinds with no leaks that I know of; you have to follow the installation instructions.
Roofing places may sell safety harnesses for roof work. These things will pay for themselves in a big hurry.
A 14' fall is to be avoided at all costs and half the people die from a ~35' fall (the other half wish they were dead).