Make sure your house is properly ventilated so you are not wasting money

The inside story on ventilation

When you read about ventilation with regard to your home’s exterior, it can be confusing. But it’s really quite simple: ventilation is simply a means to get air into – and out of – your home, specifically the attic.  You’ve no doubt heard that poor ventilation leads to energy loss. What you may not know is that poor ventilation in your attic can cause even worse problems, like wood rot, mildew, peeling exterior paint rusted nails and screws and even roof problems. The good news is that most of your ventilation problems can be easily and inexpensively addressed. And doing so during an exterior remodeling project is the best time to address it.



Attic ventilation basics

Ventilation is a system of low vents, like soffit vents, and high vents, like ridge and gable vents. To achieve proper ventilation, outside air should enter the attic low at the attic perimeter and exit high near the attic ridge.

You must provide an air gap at the overhang (soffit) and eaves to control the accumulation of moisture. Continuous soffit vents in combination with other outlets (ridge vents, mushroom cap vents, and upper gable vents) will produce the maximum amount of attic intake ventilation. 


If your roof has minimal or non-existent overhangs, you may not be able to use soffit vents. Consider installing low gable vents located near the attic ceiling but above the top of the level of the attic ceiling insulation. 

The only way to know how much ventilation is appropriate for your home is to talk to your builder or remodeler and review your local building codes. Most builders and contractors are familiar with local building codes, but you may want to look them up on your own to make sure the size, type, and placement of your vents are compliant.


Soffit 101

A soffit is the part of your home’s roof that extends past your exterior wall. A soffit vent is a vent installed into the soffit that permits outside air to be drawn up into the attic. It is one of your home’s least glamorous, yet most essential elements. In fact, research done by the Building Research Council at the University of Illinois states that if a roof could have only one type of vent device, soffit vents are recommended. A soffit vent allows inlet and outlet of air and, because they point downward, are less likely to let in rain or snow than other vents.


Selecting the right soffit

Soffit is usually offered in a variety of styles: Lanced Vent, Hidden Vent and Round Vent. Here’s what to consider so you can choose the best fit for your home:

  • Type of material and the construction of the eave
  • Local building ventilation codes and the required or suggested application methods
  • Wind-load and environmental elements based on your area of the country
  • The amount of open area that exists for air to pass through (Net Free Area)
  • Maintenance requirements – how accessible is the soffit?



Materials, benefits and drawbacks

Soffit is available in a few basic types of material: wood, aluminum, man-made composite (fiber cement and engineered wood) and vinyl. Review each type to ensure you select the one best suited for your home, environmental conditions, ventilation needs and design vision.  



Traditional wood

Usually made of cedar, pine or other common wood and plywood and vented with 8 x 12” intake vents placed at an interval.




  • Functional
  • Requires continuous painting and maintenance
  • Affordable
  • Regular maintenance is required to prevent rot
  • Standard

  • Easy to construct

Aluminum soffit


Made of aluminum with built-in ventilation. 




  • Rust and rot resistant
  • May dent
  • Maintenance-free, never needs painting

  • Installs with straight clean lines

  • Highest Net Free Area options
  • Available in a wide variety of shapes and colors

Shop for aluminum soffit

  • Typically includes a warranty

Fiber cement

Made of layered cement and vented directly in the product or through 8 x 12” intake vents placed at an interval.




  • Resists decay
  • Requires continuous painting and maintenance
  • Lasts longer than plywood
  • Likely to rot
  • Limited Net Free Area

Engineered wood (composite)

Made of wood strands or fibers combined with bonding resins and vented directly in the product or through 8 x 12” intake vents placed at an interval.




  • Similar look as wood or fiber cement soffit
  • Requires continuous painting and maintenance
  • Has factory applied primers
  • Likely to rot
  • More durable than wood


Vinyl soffit

Made of vinyl with built-in ventilation.




  • Rust and rot proof
  • None
  • Maintenance-free, never needs painting

  • Available in a wide variety of shapes and colors

  • Impact resistant

Shop for vinyl soffit

  • Typically includes a warranty


Additional ventilation products  

 Gable vents




  • Ventilates attic
  • None
  • Available in a wide variety of colors and works with all varieties of siding


Shop for gable vents