What Is Gable Vent?
A gable vent is a louvered opening high in the gable - the triangular end wall of an attic - screened against insects and slanted to shed rain. In the era before continuous soffit and ridge venting, paired gable vents were the attic's whole ventilation plan: wind blowing against one end pushed air through the attic and out the other, and on calm days warm air drifted out of both. The approach works crosswise, which is its limit - air moves through the attic's upper middle and largely bypasses the underside of the roof deck along the eaves, where heat and moisture do their damage. That is why modern systems pair low intake at the soffits with high exhaust at the ridge, washing air up the entire underside of the deck. The two philosophies interact badly: add a ridge vent to an attic with open gable vents and the ridge, needing intake, may take the easy air sideways from the nearby gables instead of pulling it up from the soffits - a short circuit that leaves the eave-to-ridge path stagnant and can draw wind-driven rain in through the gable louvers. This is the reason some installers recommend closing gable vents when converting to soffit-and-ridge ventilation, a judgment that depends on the attic's actual intake. Gable vents themselves fail quietly: torn insect screens invite birds and wasps, and aged louvers let horizontal storm rain reach stored belongings. They are checked from inside the attic in any thorough inspection, and because they live in the wall, not the roof, replacing one is siding work rather than roofing work.
Important Distinction
Note: Gable vents are wall components, not roof penetrations - they belong to the siding trade and survive a re-roof untouched. The roofing question they raise is compatibility: whether they help or fight the vents the new roof installs.
Also Known As
These are the search terms and phrases that commonly refer to this topic, so you can find it however you describe it.
How Gable Vent Relates to Other Topics
Gable vents are the pre-ridge-vent generation of attic ventilation - crosswise airflow between end walls rather than the eave-to-ridge wash modern systems are designed around.
Open gable vents near a new ridge vent can short-circuit the system: the ridge takes its intake sideways from the gables instead of up from the soffits, leaving the deck's underside unwashed.
A gable vent ventilates the attic's open volume crosswise; a ridge vent exhausts along the deck's highest line - and combining them can make the ridge vent pull rain in through the gable louvers.
Whether to close gable vents after adding ridge exhaust turns on the soffits: with generous, unblocked soffit intake the gables are redundant; with starved soffits they may be the only intake the attic has.
Aged louvers and torn screens let horizontal storm rain through a gable vent - a water entry that stains the attic floor at the end wall and is routinely misread as a roof leak.
A thorough inspection looks at gable vents from inside the attic - screen condition, daylight through closed louvers, water staining below - because they sit in the wall and drone photos of the roof never see them.
Ventilation upgrades are part of the roof's energy system, and a gable-vent attic converting to soffit-and-ridge airflow only realizes the cooling benefit if the old and new vent philosophies are not left fighting each other.
Questions about Gable Vent?
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