Passive Roof Vents: Helping Your House Breathe Easy

Passive Roof Vents for Home Cooling Roof Vent Benefits
Image: Air Vent Inc.

Passive roof vents expel excess heat and moisture. The key is to balance incoming air with outgoing, and perform an annual maintenance checkup.

Passive roof vents encourage natural air flow and work without the aid of motorized fans. Roof vents enhance the overall comfort of the house by providing escape hatches for hot, stale, moist air, which can reach temperatures of 150 degrees in summer.

In winter, you need to dump that hot air before it condenses, which can lead to rot and mold. Warm air trapped in the attic during winter also may cause rapid melting of snow, which then refreezes as ice dams--mini glaciers that can push up shingles and peel off gutters and soffits.

How Much Roof Ventilation?


Check Your Roof Vents

You or a professional roofer should check your roof vents annually.

  • Repair screen rips or tears and damaged flashing.
  • Check for rust or rot around the framing or flashing.


Roof Vent Options

  • Static vents have no moving parts. They're basically protected holes in the roof that allow air circulation. They come in various designs -- roofline, dormer, roof louver, or eyebrow vents--and are installed in an even line across the roof. Some pros swear by them; others think they tend to leak. They cost between $35 and $50 per vent to install.

For areas with little wind, a power-assisted vent is an option.

Soffit Vents Provide a Breath of Fresh Air

Getting rid of hot air is just part of the equation. You also need intake vents, which are usually soffit (or under-eave) vents. Made of aluminum or vinyl, they contain tiny perforations or slits for airflow, and are available as either narrow strips that butt together, or as smaller, wider vents that fit between roof joists. 

Soffit vents are most effective when used with a ridge vent. Most new houses have soffit vents, and they can be retrofitted on old ones. If you have only small gable or roof vents, putting in soffit vents will increase airflow.

Related: Inspecting Your Roof to Get Ahead of Problems

Laura Fisher Kaiser

Laura Fisher Kaiser

Laura Fisher Kaiser is a contributing editor to “Interior Design,” a former editor of “This Old House,” and has written for such titles as and “The Washington Post.” She and her husband have renovated their Folk Victorian in Washington, D.C. -- and lived to tell about it.