Ask Angie: What happens if my roof isn't properly ventilated?

angieslist.comJune 27, 2014 


Angie Hicks


Dear Angie: What happens if my roof isn't properly ventilated? — Rick M., Collegeville, Pa.

Dear Rick: What you and other homeowners don't know about attic ventilation might cost you in possible roof damage.

The Federal Housing Administration recommends at least 1 square foot of ventilation for every 300 square feet of attic space. Top-rated roofing experts tell our team that many attics are insufficiently or improperly ventilated.

They say that poor or non-existent ventilation might cause attic temperatures to rise to 150 degrees or higher in the summer. That can lead to damaged shingles and other roofing materials as well as a buildup of condensation and development of mildew and mold.

Pro roofers say ventilation systems should bring the attic temperature as near as possible to the outside air temperature. During winter, cool air entering the attic through intake vents above the eaves helps prevent ice damming, according to Energy Star, an Environmental Protection Agency-driven program that promotes energy efficiency. Ice dams develop when snow melts, often due to attic heat buildup, and then refreezes at the roof's edges.

There are two main ways to vent an attic:

■ Rooftop turbines, which spin via wind power.

■ Ridge vents, which cut into the peak of the roof and extend its length.

Keep in mind that a proper ventilation system requires intake vents as well an exhaust component, preferably in equal proportion. Also, when insulating the attic, which is a good idea for cutting energy costs and being more comfortable in your home, be sure not to cover any vents.

The cost to ventilate your attic varies according to vent type, roof size and other factors. A ridge vent generally costs more than a turbine because it requires a cut along the roof length. A turbine requires that only a small section of roof be removed.

Even if you're comfortable with getting on your roof, consider hiring a professional to inspect or work on it. Improper attic ventilation can void your roof's warranty or lead to an expensive roof repair or replacement. Another option for determining if you have sufficient attic ventilation is to arrange for a home energy audit.

A service provider might offer a roof inspection at no charge or it could cost a few hundred dollars.

If you hire a company, make sure it has positive reviews and is appropriately licensed, insured and bonded. Ask for references and contact those consumers. Get all details in writing, including payment terms.

Angie Hicks compiles the best advice from the most highly rated service pros on to answer your questions. Ask Angie your question at

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