Maintaining Proper Attic Ventilation Keeps Your Roof in Good Shape
The effects of inadequate attic ventilation travel both down and up. It’s well known that a broiling hot attic conducts heat down into your living spaces, making the A/C work overtime to offset it. Most people are aware, too, that excess attic humidity can saturate attic insulation and trigger mold that affects indoor air quality. However, attic ventilation issues also impact what’s overhead: your roof. The right temperature for an attic is as close to the outdoor temperature as possible, with a relative humidity that approximates the living spaces. Here’s how the roof is affected when attic ventilation doesn’t meet these standards.
- Sustained high attic temperatures can warp and split plywood roof sheathing. This, in turn, buckles the shingles on the exterior of the roof. Water intrusion occurs at the next rainfall, permanently damaging the roof sheathing, as well as other wooden structural components.
- High levels of attic humidity accumulating during the day condense when the attic cools overnight. This saturating moisture soaks interior wooden components of the roof and causes warping and buckling.
- In an under-ventilated attic, heat accumulates at the upper portions, warming the underside of the roof near the peak. Meanwhile, lower areas of the roof remain close to air temperature. When this scenario occurs after snowfall, snow melting quickly off the warmer upper roof refreezes down near the gutters where the roof is cold. Ice dams form and snow melt accumulates on the roof. Because shingling isn’t designed to seal out standing water, severe leakage may result, damaging roof sheathing, attic structure and even causing ceiling leaks in living spaces.