A ridge vent is the long opening along the peak of a roof that lets hot air escape from the attic. Combined with soffit vents (intake at the eaves), it creates continuous attic ventilation — keeping the attic cooler in summer, drier in winter, and extending shingle life. Most modern roofs have ridge vents; older roofs often have static box vents that ridge vents replace.
This guide covers installing a continuous ridge vent on an existing asphalt shingle roof — typically done during shingle replacement.
Before you start
Three things to settle:
1. Ridge vents need matching soffit intake. Ridge vent without soffit intake doesn't move air. Verify soffits are vented (continuous soffit vent or individual vents) before installing ridge vent. Both required for continuous ventilation.
2. Cut sheathing to allow airflow. Ridge vent has a 1-2 inch slot opening cut along the ridge — sheathing on both sides of ridge cut. This is where attic air flows out. Skipping this step: vent looks installed but doesn't ventilate.
3. Roof work safety mandatory. Working at peak of roof: fall protection (harness anchored to structural), proper ladder access, and weather suitable. Don't ridge vent install in rain or wind.
What you'll need
Tools
- Reciprocating saw or circular saw with utility blade
- Hammer or roofing nailer
- Tape measure
- Chalk line
- Utility knife
- Roofing safety harness + tie-off
Materials
- Continuous ridge vent (CertainTeed Roll Ridge or GAF Cobra)
- Roofing nails (1.5 inch typical)
- Cap shingles (matching roof shingles) — to cover the ridge vent
- Roofing cement (for end seals)
- Underlayment (if exposed during install)
1-2 inch slot in sheathing on each side of ridge
Without this slot, ridge vent doesn't ventilate.
Cut a 1-2 inch wide slot in sheathing along each side of the ridge (slot width depends on vent product).
Total opening: 2-4 inches along the ridge length.
Step-by-step instructions
Verify soffit ventilation exists
Look up under the eaves — soffit vents should be visible.
Continuous soffit vent strip OR individual round/rectangular vents.
If no soffit vents: install before adding ridge vent (separate job).
Both intake and exhaust required for continuous ventilation.
Strip existing shingles from ridge
Remove cap shingles along entire ridge.
Pull nails; expose underlayment.
Save existing cap shingles if reusing (rare; usually replace).
Snap a chalk line for cut location
On each side of the ridge: chalk line at appropriate distance from peak.
Slot width: typically 1-2 inches per side, per ridge vent product spec.
Verify chalk line is parallel to ridge.
Cut the slot in sheathing
Reciprocating saw or circular saw — set blade depth to JUST through sheathing (not through rafters).
Cut along chalk line on each side of ridge.
Continuous slot the length of ridge.
Pull cut sheathing pieces out.
Install ridge vent product
Continuous ridge vent (rolled or sectional product).
Position centered over the cut slot.
Nail through vent's mounting flanges into sheathing.
Per manufacturer's nailing pattern.
Apply cap shingles over ridge vent
Cap shingles cover the visible ridge.
Ridge vent has sheltering profile; shingles overlap properly.
Nail cap shingles per manufacturer (typically 4 nails per cap).
Install from one end to other; overlap each cap.
Seal ridge ends
Closed ends of ridge: roofing cement on ridge vent ends to seal against weather.
End caps fitted (some products include).
Prevents water entry at ends of vent.
Inspect for proper coverage
Walk along ridge from below.
Cap shingles should be flat and well-aligned.
No exposed underlayment, sheathing, or vent profile.
Clean professional look.
Verify airflow (smoke test)
From within attic: in cool weather, hold a smoking incense stick near soffit vents.
Smoke should be drawn upward and out at ridge.
Verifies ventilation is working.
Attic should feel cooler than outside in summer (vs without ventilation).
Old box vents removed and patched
If ridge vent replaces older box vents: remove the box vents, patch sheathing, shingle over.
Old box vents create competing exhaust paths that reduce ridge vent effectiveness.
Common mistakes that cost you
- No soffit intake. Ridge vent doesn't draw air. Install soffit ventilation.
- Skipping sheathing cut. Vent looks installed, doesn't ventilate. Cut slot mandatory.
- Cutting through rafters. Structural damage. Set blade depth to sheathing only.
- Wrong cap shingle pattern. Water entry around ridge. Follow manufacturer's pattern.
- Working in poor weather. Slip risk; partial install can leak. Wait for dry weather.
Frequently asked questions
Do I need a ridge vent if I have soffit vents and a power vent?
Power vents (gable or roof-mounted): provide active exhaust, but require energy.
Continuous passive ventilation (ridge + soffit): preferred for long-term roof health.
Mixing systems can short-circuit ventilation; engineer determines best approach.
Can I install ridge vent on a roof without removing shingles?
Cap shingles must be removed for sheathing slot cut and vent install.
Other shingles can stay if they're not at the ridge.
Often combined with full re-roof.
What's the lifespan of a ridge vent?
Plastic ridge vents: 25-30 years (typical roof life).
Metal ridge vents: 40-50+ years.
Match life to expected roof life.
When to call us instead
Ridge vent installation is part of every re-roof we coordinate. Our team handles roofing as part of larger renovation work.
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