Roof Ventilation: Don't Overlook This Potentially Damaging Problem

25 June 2015
 Categories: , Blog


Roof damage doesn't just come from above. While hail, rain infiltration, storm damage, and regular wear from the elements are all well known problems for roofs, fewer people pay attention to how their ventilation might be causing damage. But poor roof and attic ventilation can have some major consequences for your home and roof when hot air and moisture aren't properly vented out.

Hot Weather Damage

When the temperature outside is high, one of the main consequences you'll see from poor ventilation is that your home heats up uncomfortably. You may need to run your air conditioner more to keep the interior of your home comfortable, depending on how high temperatures get. If the temperature gets very high, you may see expansion and buckling in your roof—especially in the underlayment.

Cold Weather Damage

In the winter, when the weather turns cold and snowy, poor ventilation is an even more serious problem. Hot air that is trapped under the roof is a major cause of ice dams; the hot air heats the roof, melting the lowest layer of snow. As this melted snow slides down the roof, it cools back down and refreezes into ice.

Once ice begins to build up at the edge of the roof, the weight of it can damage roofing and gutters. And as more snow melts on the roof, the ice dams block the water from flowing down and off the roof; instead, this water can end up backing up into the roof itself, causing structural damage as well as leaks.

Moisture Damage

Just as proper ventilation prevents heat from being trapped under the roof, it also carries away moisture. If moisture is allowed to build up, on the other hand, your roof becomes an attractive habitat for mold. Once mold begins to grow, it can be a real pain to get rid of, especially when it's growing in hidden areas above ceilings or behind walls.

Excess moisture can also cause some materials, such as wood, to swell up, leading to shifting in the structure of the roof. And metal pipes, fasteners, and other fittings may begin to rust in high humidity.

What You Can Do

Look for the signs of poor ventilation. If ice dams often form on your roof or you notice that your attic is uncomfortably hot, you should check (or hire a roofer to inspect) your roof ventilation. Other signs include rusting metal in the attic or under the roof, mold that originates in the attic or roof, or abnormally high energy costs when running an air conditioner in hot weather. If you are concerned about your roof, consider scheduling an appointment with North Shore Roofing & Drainage Ltd.