This is a dryer or a bathroom vent that was added to a second floor bathroom or laundry room. The exhaust from this vent will be warm, damp air.
- The open tube is inviting to birds, and other small critters to nest in.
- The opening can allow small animals into the house.
- The tube end can get covered in snow and therefore get clogged.
- Warm wet air is blowing onto the roof shingle. This isn’t good, but is unlikely to cause serious harm.
This kind of unfinished work above the roof line is common. Few homeowners will go up on a ladder to see for themselves. I advise people to ask the neighbors to allow a look. Or ask the contractors to take pictures of their work. Or both.
Other common mistake regarding bathroom and dryer vents is routing the open end into the attic. The warm damp air is perfect for creating a happy environment for attic mold.
The cover allows air out, but has a flap that keeps it closed when not in use. The cover should protect the vent from rain. A cage-like grill will discourage birds and small rodents from nesting in the sometimes-warm — and inviting — tube.