How to Improve Your Attic Ventilation

When we consider our roof and its condition, our initial thoughts are informed by immediate visual cues: How do the shingles look? Are the eaves clear? Are there any signs of wear and tear? One area that’s often missed, which deserves special consideration, is attic ventilation.

Any roof that sits above a lived-in or used space should have proper attic ventilation. All homes produce damp air from resident’s everyday acts, like showering, cooking, the running of faucets, and even breathing — and all this warm air will rise toward the roof. Attic ventilation allows cool, fresh air to enter the attic while allowing this moist, damp air to exit.

Improper or damaged attic ventilation that doesn’t permit proper airflow and circulation can cause serious damage to the integrity of your roof and your home. This is especially important here in Ontario, where temperatures and humidity fluctuate.

How Poor Ventilation Affects Your Attic and Your Home

During any season, poor attic air ventilation can damage your home’s exterior and interior. Here’s how.

Mold and Wood Rot

These are both signs of poor attic ventilation. During the cooler months, condensation will build in the attic if the damp air can't escape. Over time, this condensation will lead to mold and wood rot — damaging the integrity of the roof.

Ice Dams

Ice dams may also form because of poor attic ventilation. An ice dam is a thick layer of ice that builds just above the edge of the roof. An ice dam holds melting roof water in place, stopping it from flowing into the eaves.

Ice dams are detrimental because they cause roofing materials to become waterlogged. When the attic warms with trapped hot air during the day — due to improper or poor ventilation in attic areas — it will thaw the snow and ice on the roof above, allowing it to seep under roof shingles. During the night, this water freezes, expanding underneath the shingles, then thaws again during the day — leaving you open to a potential leak. An ice dam can cause serious damage and may warrant roof repair emergencies.

Roof Degradation

This moisture accumulation can also cause your exterior roof elements to degrade. Flashing and nails may start to rust, and mildew can even grow underneath shingles, causing them to rot.

Increased Energy Bills

Poor ventilation in attic spaces will lead to higher energy bills year-round. In the summer, if hot air can’t properly escape from the attic, your air conditioner will work overtime to counteract this. And in the winter, moisture will seep into your attic’s insulation, reducing its insulating properties.

Reduced Indoor Air Quality

Another detrimental effect of poor attic ventilation is lowered indoor air quality. Trapped air in the attic may contain mold spores, insulation fibres and dust; over time, it can spread to the floors below through vents, which can aggravate allergies and may even cause respiratory challenges.

Quicker-Than-Average Replacements

Poor ventilation in the attic will also cost you extra money in the long haul. Consistent dampness will wear down your attic insulation, meaning it will need to be replaced sooner than later. And poor air circulation in the attic will damage shingles in both hot and cold climates, shortening their lifespan as well.

Signs of Poor Attic Ventilation

There are a few telltale signs that your home is poorly ventilated that are visible from the interior and exterior of the property. These signs will tell you if the current ventilation isn't operating correctly or if the system that's in place isn't sufficient enough for the attic size.

  • If you have interior access to your attic, head up there on an especially cold day. If you can see frost or moisture on the walls or the underside of the roof, unfortunately, this may indicate poor attic ventilation.
  • Get a ladder if necessary, and touch a ceiling below the attic on a hot day. If the ceiling feels especially warm, this is also a sign that the attic has no ventilation or that the ventilation is compromised, thus raising your air conditioning bills.
  • As discussed, ice dams are a visual clue of compromised or poor attic ventilation or a sign that the attic has no ventilation.
  • Another visual insight into your attic ventilation is to look for vents from the outside of the home. Vents come in different shapes and forms; they may look like a series of boxes across the roof or a turbine on the rooftop. Soffits — the finished surface on the underside of the roof overhang — is another visual indicator of attic ventilation. We’ll discuss vents further, shortly!

A benefit to checking the roof area of the home, especially during wet months, is to check for seasonal wear and tear. Seasonal spring maintenance for flat roofs is essential as flat roofs are prone to feeling the stress of heavy rains and fluctuating temperatures.

A large tan brick, new build house with ridge vents

How Can You Improve Your Attic Ventilation?

There are several steps towards improving your attic’s ventilation, though personal needs will vary based on circumstance and what is already in place.

First, check your bathroom and kitchen vents and ensure they operate as they should. Unfortunately, simply opening a window in your bathroom after a long bath or a hot shower won’t suffice. An extractor fan is the most effective and efficient way to remove moisture from your bathroom and kitchen. Consider installing an extractor vent if you don't have one.

If you have established that your vents aren’t working efficiently using our ‘telltale signs’ list above, or if your attic has no ventilation, it might be time to install vents or upgrade your current models. At Professional Roofers, we are proud to offer attic ventilation services.

As mentioned briefly above, ventilation options come in various forms:

Box Vents

These look like boxes across the roof. They are installed over holes that are cut in the rooftop. They are passive or static and function by using natural convection to release hot air from the attic.

Soffit Vents

Soffit vents are also static. They provide constant air into the roof’s ventilation system.

Gable Vents

If aesthetics is important, gable vents are one of the best attic ventilation options. They’re located at the peak of a gable (or triangular) roof on the external wall. They have slatted louvers to keep animals out.

Ridge Vents

Another static vent, these are usually installed along the top of the roof at its highest point — also known as the ridge. While one of the most effective and best attic ventilation options (especially when partnered with Soffit vents), installing ridge vents involves removing large roof sections.


Turbines move with the wind and are great for windy areas (like Toronto). On a blustery day, they can provide more air circulation than static vents.

Solar Powered Vents

These are durable and lightweight and require little maintenance. The 4 Seasons attic vent is made with the Canadian climate in mind, meaning that they’ll stand up to hot sunny summers and freezing snow and hail.

Power Vents

These use motors that rotate fans to remove trapped heat from your attic. They can be up to four times more effective than static vents, giving an immediate boost to your attic air ventilation.

Getting Attic Ventilation Installed and Checked

Not only is proper attic ventilation important for the integrity of your attic and roof, but it also keeps any personal possessions you might be storing in the attic mold and mildew free.

At Professional Roofers, we understand the intricacies and the importance of properly installed roof and attic air ventilation; furthermore, we’re innately familiar with the regional climate, so we can advise you on how much ventilation you need and the best type of ventilation system for your home.

So if you’d like to learn more about proper attic ventilation or have any other questions about your roof, connect with us today — we’re always happy to help.

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