Attic Ventilation: A Home Inspector's Guide | Guest Post

Proper attic ventilation is a critical component of a healthy and efficient home. Airflow through the attic space helps to regulate temperature inside the house and reduces moisture that could lead to mold, damaged roof shingles and ice dams.

The attic needs a balanced ventilation system with as much air entering through the intake vents as leaves through the exhaust vents. Ideally, the intake vents are installed along the edges of the roof, at the lowest point in the attic, in the soffits. The exhaust vents are installed along the ridge, the highest point of the attic. This causes a natural stack effect, or continuous cycle, where when the warm moist air rises, it pulls cooler, dryer air in behind it.

“The goals are to keep the air moving,” says Layton Icabone, Product Manager with Gorilla Roof in Denver Colorado “and the attic space at or near the outside temperature, not cooler.”

HOW TO TELL IF YOUR ATTIC IS PROPERLY VENTED

Fortunately, your home will tell you if its attic lacks a balanced ventilation system. A few signs include:

• Excessively warm living areas caused by the heat having no place to go.
• Moisture or frost in your attic during the winter.
• Ice dams forming at the edge of your roof in winter.
• The lack of vents in your eaves or exhaust vents on your roof.
• Rotting or decaying home exterior.
• Peeling paint.
• Roof damage

OPTIONS FOR ATTIC VENTILATION

According to Layton, there are two types of exhaust vents for attics—static and powered. A static vent is basically a hole strategically placed to allow warm air to

escape. They include ridge vents, that run along the length of the roof ridge, box-style cap vents, or turbine vents. A powered vent includes a fan.

Intake vents include those in the soffits and those in the gables. Gable vents can act as both intake and exhaust, depending on the wind direction and speed. However, because they’re placed in the highest part of the home, they operate best as an exhaust vent.

ATTIC EXHAUST VENT TYPES: PROS AND CONS

Every type of attic ventilation has pluses and minuses. Here, we're breaking them down so you can choose the best option for your home.

RIDGE VENTS

According to Layton, ridge vents come in 4-foot sections and run along the spine of the roof.

Pros

• Almost invisible, they blend in with your shingles
• Aesthetically pleasing
• Provide ventilation without the aid of power or wind
• Most effective passive vent that rarely leaks

Cons

• Works best with soffit vents
• Easier to install when re-roofing the home
• Matching shingles for a retrofit may be difficult
• Must close in other vent types and install an adequate intake vent

STATIC VENTS

Also called box vents, static vents have no moving parts to direct airflow. Styles of static vents include the Mushroom, the Turtle and the Dormer vent, referring to their shapes.

Pros

• Easier to add to an existing roof
• Can be installed anywhere on the roof
• There are no moving parts

Cons

• Several are required
• Not as attractive as a ridge vent
• Some styles become homes to birds
• Need frequent inspections

TURBINE VENTS

Though technically a static vent, turbines get a class all their own because the wind provides their power. Experts recommend paying for the higher quality ones from the start. How many you need depends on the size of your roof.

Pros

• Work harder when the wind is blowing
• You’ll need fewer turbine vents than other static vents

Cons

• Steel ones may rust
• May make noise or stop working overtime
• Some consider them unsightly

POWERED VENTS

Aptly named because they require solar or electric power to turn a fan that moves the air.

Pros

• More expensive models may include thermostats and hydrostats you can set to come on at a certain temperature or humidity level
• Move more air out of the attic than a static vent
• Can be mounted on the roof or in the gable

Cons

• May pull more cool air from air leaks in the attic than from the soffit vents
• Adds to your cooling costs
• Must have proper intake vents or the motor may wear out prematurely
• Require regular inspections to make sure they’re running properly
• Require wiring which may involve the cost of hiring an electrician

ATTIC INTAKE VENTS: PROS AND CONS

There are two main types of intake vents. The style of your home and budget will help determine which is the proper pick for you.

SOFFIT VENTS

Perforated sections of soffit every few feet, or running the entire length of the eaves, make up your soffit vents.

Pros

• Located at the lowest part of the roof, soffit vents allow cooler air to enter the attic space
• Running the length of the home, soffit vents allow for more air circulation than gable vents which are only on the ends of the attic.

Cons

• Most effective when used with a ridge vent
• Homeowners tend to cover them with insulation, which blocks the airflow

GABLE VENTS

You find gable vents in the uppermost point of the gables of the roof. They can be as unobtrusive as a perforated piece of vinyl siding. Or, if your gable end faces the street, you can opt for something more decorative.

Pros

• Can act as both intake and exhaust vents.
• The most inexpensive option
• Can be used with an attic fan

Cons

• Can’t use with some roof lines
• When used alone, the least effective method of cooling the attic

OTHER THINGS TO CONSIDER

First, take care not to block any attic ventilation you do have. When insulating an attic, homeowners may inadvertently cover soffit vents, rendering them useless. Keep all insulating material away from the eaves or install baffles between the rafters to direct the air from the vent up along the roof deck.

If you use your attic for storage, don’t fill it too full. When the attic is too full it inhibits airflow and causes moisture build-up.

We also suggest choosing a local contractor with a proven track record and experience with the choices specific to the area. You want someone who understands and knows what they’re looking at.

The views, opinions and positions expressed within this guest post are those of the author alone and do not necessarily represent those of the Denver Metro Association of Realtors®. The accuracy, completeness and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them.

If you are interested in submitting a guest post, please contact Sarah at sgoode@dmarealtors.com.