Ventilation 101: How to Keep Your Attic from Turning Into a Sauna

Most homeowners don’t think about their attic unless something goes wrong. But during the hot, humid summer months in Connecticut, poor attic ventilation can cause a lot of problems. Some you’ll feel in your cooling bills, and others you might not notice until it’s too late.

Here’s why proper attic ventilation matters and how to know if your home needs an upgrade.

Why Your Attic Needs to Breathe

Your attic should be the same temperature as the air outside. That might sound surprising, but it’s true. In the summer, without proper airflow, your attic can easily reach 130°F or higher. That heat doesn’t just stay in the attic - it radiates down into your living space, forcing your air conditioner to work harder and driving up energy costs.

Hot, stagnant air can also cause your roofing materials to age prematurely. Shingles can blister, underlayment can warp, and moisture can build up, leading to mold, mildew, and even wood rot.

Good ventilation helps control both heat and moisture, keeping your attic and roof in better shape, and your home more energy-efficient.

The Basics of a Ventilation System

A well-ventilated attic has two things: intake and exhaust. These work together to create a continuous flow of air.

• Intake vents (usually located in the soffits under your roof overhang) pull fresh air into the attic.

• Exhaust vents (at the roof ridge, gables, or high up on the roof slope) allow hot, humid air to escape.

This system relies on the natural movement of air—cool air in, hot air out.

Common Ventilation Types

• Ridge vents: Run along the peak of your roof and are often paired with soffit vents. They’re effective and barely noticeable from the street.
  Soffit vents: Located under your eaves, they bring in cool outside air.

• Gable vents: Installed on the walls of the attic, often used in older homes.

• Powered attic fans: Use electricity to actively pull hot air out. These can be helpful but aren’t always necessary if passive ventilation is working properly.

Signs of Poor Attic Ventilation

• Your upstairs rooms are always hotter than the rest of the house.

• You notice high energy bills in the summer.

• Your roof shingles are curling or deteriorating faster than expected.

• There’s mold or a musty smell in the attic.

• You see frost or condensation in the attic during winter (yes, ventilation matters year-round).

Here in Connecticut, we deal with humid summers and cold winters, which means both heat and moisture are issues. That makes proper attic ventilation even more important. It’s not just about comfort, it’s about protecting your roof, improving air quality, and saving on long-term energy costs.

If you’re unsure whether your attic is properly ventilated, a quick inspection by a professional can help. It’s one of those home systems that’s easy to overlook, until it’s not.

Bob O’Donnell is the owner of O’Donnell Bros. Inc., a Bristol-based home improvement company established in 1975. Got a home issue you’d like Bob to tackle? Email info@odonnellbros.com with the subject line “Ask the Pro.” To contact Bob for your remodeling needs, call O’Donnell Bros. Inc. at (860) 589-5155 or visit http://www.odonnellbros.com. Advice is for guidance only.

Attic Ventilation is Key for the Home

I recently did work for a homeowner who got the shock of her life when we removed her old roof and found sheet after sheet of black, rotten plywood. The homeowner couldn’t believe it and asked me how the plywood could be so damaged if she had never had a roof leak. 

The answer is quite simple and a lot more common than you think. In our area of Connecticut, nearly all attics don’t have enough insulation and aren’t ventilated properly. I meet people who need a new roof and want me to just lay an extra layer of shingles over top of what they already have to save money. What they don’t realize is how much deterioration exists that they simply can’t see.

With a roof, airflow is absolutely crucial. Attic ventilation allows your home to “breathe” by taking in air from the outside and letting out air from the inside. Too many homes that I work in aren’t properly ventilated, in fact, most have their bathroom and even dryer vents going into the attic instead of outside. In order to have proper ventilation, your home needs a system that includes intake ventilation through the soffit or a new product called SmartVent which is installed on top of the roof near the gutter edge. Louver vents were typically used at an exhaust vent in the 1950’s and 1960’s but now ridge vents are more common. If your house has both louver vents and ridge vents, the louver vents should remain closed, otherwise, the louver will act as an intake vent and will only cool the top third of the attic. 

In the colder months, it’s not uncommon for me to see frost on attic plywood because of subpar insulation. Insulation and ventilation work hand in hand - the ventilation controls the airflow and the insulation controls the temperature. You’re probably familiar with insulation - it’s a cotton-looking fiberglass material that often comes in pink or yellow rolls. It can also be loose-filled into tough to reach areas with a blowing machine. Remodeling professionals use insulation between walls, in attics and in basements to retain heat in the house in the winter and keep it cooler in the summer. However, without proper ventilation, the insulation is just as susceptible to moisture and deterioration as the plywood.

My customer didn’t venture into her attic, so she never noticed the problem. What she thought was a simple roof replacement ended up being a bigger job simply because after years of decay, the plywood she had was no longer strong enough to properly support the new roof. Ignoring the problem would have voided the new roof’s 30-year warranty.

The lesson for this week? If you’re going to reroof your home, make sure that the plywood is healthy and that your contractor has given you a thorough plan to ensure that your home is properly insulated and ventilated. It might cost a bit more today, but it will regulate the heat and cooling in your home for years to come, saving you on energy costs and giving you more comfort as well as peace of mind for the health of your house.

Bob O'Donnell is the owner of O'Donnell Bros, Inc., a Bristol-based home improvement company established in 1975. Email your questions for Bob to info@odonnellbros.com with the subject line “Ask the Pro”. All questions may be considered for publication. To contact Bob for your remodeling needs, call O'Donnell Bros, Inc. at (860) 589-5155 or visit www.odonnellbros.com. Advice is for guidance only.

What's Under the Roof?

I recently did work for a homeowner who got the shock of her life when we removed her old roof and found sheet after sheet of black, rotten plywood. The homeowner couldn’t believe it and asked me how the plywood could be so damaged if she had never had a roof leak. 

The answer is quite simple and a lot more common than you think. In our area of Connecticut, nearly all attics don’t have enough insulation and aren’t ventilated properly. I meet people who need a new roof and want me to just lay an extra layer of shingles over top of what they already have to save money. What they don’t realize is how much deterioration exists that they simply can’t see.

With a roof, airflow is absolutely crucial. Attic ventilation allows your home to “breathe” by taking in air from the outside and letting out air from the inside. Too many homes that I work in aren’t properly ventilated, in fact, most have their bathroom and even dryer vents going into the attic instead of outside. In order to have proper ventilation, your home needs a system that includes intake ventilation through the soffit or a new product called SmartVent which is installed on top of the roof near the gutter edge. Louver vents were typically used at an exhaust vent in the 1950’s and 1960’s but now ridge vents are more common. If your house has both louver vents and ridge vents, the louver vents should remain closed, otherwise, the louver will act as an intake vent and will only cool the top third of the attic. 

In the colder months, it’s not uncommon for me to see frost on attic plywood because of subpar insulation. Insulation and ventilation work hand in hand - the ventilation controls the airflow and the insulation controls the temperature. You’re probably familiar with insulation - it’s a cotton-looking fiberglass material that often comes in pink or yellow rolls. It can also be loose-filled into tough to reach areas with a blowing machine. Remodeling professionals use insulation between walls, in attics and in basements to retain heat in the house in the winter and keep it cooler in the summer. However, without proper ventilation, the insulation is just as susceptible to moisture and deterioration as the plywood.

My customer didn’t venture into her attic, so she never noticed the problem. What she thought was a simple roof replacement ended up being a bigger job simply because after years of decay, the plywood she had was no longer strong enough to properly support the new roof. Ignoring the problem would have voided the new roof’s 30-year warranty.

The lesson for this week? If you’re going to reroof your home, make sure that the plywood is healthy and that your contractor has given you a thorough plan to ensure that your home is properly insulated and ventilated. It might cost a bit more today, but it will regulate the heat and cooling in your home for years to come, saving you on energy costs and giving you more comfort as well as peace of mind for the health of your house.

Bob O'Donnell is the owner of O'Donnell Bros, Inc., a Bristol-based home improvement company established in 1975. Email your questions for Bob to info@odonnellbros.com with the subject line “Ask the Pro”. All questions may be considered for publication. To contact Bob for your remodeling needs, call O'Donnell Bros, Inc. at (860) 589-5155 or visit www.odonnellbros.com. Advice is for guidance only.