Does a Shingle Roof Sweat?

Poor Ventilation

• Poor ventilation is one of the prime causes of roof shingle condensation. If your attic lacks ventilation, moisture -- in the form of humidity -- can become trapped, causing water vapor to penetrate the shingles and other roofing materials. Roof vents can improve attic ventilation dramatically by permitting a continual flow of air from the enclosed space to the outside. If you cannot afford to have proper ventilation installed, fans can also improve the air flow in a pinch.

Dew and Rain

• Condensation can also form on roof shingles as a result of external conditions. For instance, excessive moisture from morning dew can collect on the surface of the shingles, and rainwater can become trapped as well, causing the shingles to remain moist long after the rain has stopped. This happens because asphalt shingles are porous, meaning that they absorb and trap water. When moisture penetrates the asphalt surface, it can prove difficult to dry up without direct sunlight.

Warnings

• If you have excessive condensation problems with your roof, consider taking action immediately. Roofing materials like shingles can corrode and suffer permanent damage as a result of regular moisture penetration. In addition to properly ventilating your attic, you can minimize condensation by installing a strong roof insulation within the attic. A roof underlayment installed beneath the shingles also functions as a strong moisture barrier, as does the application of a vapor retarder, also called a vapor barrier, above the drywall ceiling.

What About Metal?

• If you live in an area with high humidity and your shingle roof is constantly exposed to excess moisture, you might consider tearing out the old asphalt shingles and installing a more durable metal roof. Metal roofing can also sweat, and you have to install it correctly to prevent moisture from entering your home. But when properly laid out, a metal roof can withstand moisture much more effectively than asphalt shingles and last a much longer time.