Most new vents fans enclosers have built in dampers to prevent backflow, If
not install and external one then will be OK.

Also they make a system that has an inline fan unit in the attic that all
vents run to, no noise with those but are pulling air from all vents when
only one is needed.


"SilverUnicorn" wrote in message
...
Our house is 4 years old. We have one roof vent and we have 2 1/2
bathrooms.


We line in PA.

Chris

"Jim" wrote in message
...
Can I exhaust 3 bathroom vents through one roof vent or does each
bathroom
vent need its own roof vent?