How do you replace roof vents, and when should roof vents be replaced?
Short answer. Replace roof vents when hoods are cracked by hail or brittle from sun, metal vents are rusted through, screens are torn, or the vent leaks, and always when the roof itself is replaced. To replace one, release the shingles above it, remove the old vent's nails, slide the new vent into the same opening with its flange under the upper shingles, then nail and seal it.
When to replace
- After hail: plastic hoods crack and metal hoods dent. Cracked hoods leak, and dented ones may still be part of a storm claim.
- Sun damage: older plastic vents become brittle and chalky in Georgia's UV.
- Rust: metal vents rust at seams and nail holes over time.
- Torn or missing screens: let in birds, wasps, and squirrels.
- Leaks: stains in the attic below the vent.
- Roof replacement: vents come off with the old shingles and new ones go in.
Swapping a box vent
- Break the seal on the shingles above and beside the vent.
- Remove the nails holding the old flange and lift the vent out.
- Check the decking around the opening for rot, and repair it if needed.
- Match the new vent's base to the existing opening, or adjust the opening to its template.
- Slide the new vent in with the top and sides under the shingles and the bottom over them.
- Nail the flange where it will be covered, renail the shingles, and seal exposed nail heads.
Upgrade options
- Metal vents resist hail cracking and UV better than plastic.
- Vents with internal baffles handle wind driven rain better.
- On a gable roof, replacing a row of box vents with a ridge vent during a reroof removes several penetrations.
- Removing an old turbine or power fan in favor of passive vents eliminates moving parts.
Keep the exhaust area at least as large as before, and do not mix types. See ridge vent vs box vents and Georgia hail season.