Attic Plywood Wet

Moisture frost and ice buildup on roofing nails.

Attic plywood wet.

Buckled or damaged roof sheathing. Water or drip marks scattered on the attic floor. Wet sheathing was found in attic area due to lack of venting. Moisture or frost on the roofs sheathing.

Moist or wet insulation. Most attics are dry plywood is a smart vapor retarder with variable permeance. If any moisture makes its way to the plywood the damp plywood will dry out on hot sunny days. It s not a vapor barrier.

This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate. In this photo of very dark mold in an attic in a wet attic mold which we found to be brown in the microscope looked black on the plywood. Black mold in attics. Mold usually causes a musty odor and may cause staining that may be black brown gray white yellow or green.

Prolonged wetness will rot out the roof sheathing. Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the. Reader comments q a. The mold itself may have a cottony texture but can also be velvety leathery or.

In the vast majority of cases the mold growth is caused by condensation. If you have ceiling leaks only in the spring it may be that ice has been forming on the sheathing all winter and it suddenly melts when a warm spell arrives. The insulation was contaminated and we inspected the attic side of the ceiling drywall below for signs of leak stains or mold. Often this is first noticed when re shingling.

Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest. If you suspect you have moisture problems in your attic check for the following indications of excess moisture in the attic. If your insulation particularly the cellulose on top is uniformly damp over much of the area then pretty certain it is condensation or frost forming which is not uncommon at all even in ventilated attics when the outside temp gets below about 15 or so. There are many signs that an attic is wet.

The black attic mold shown here confirms that this attic had a serious venting and moisture problem including moisture from sources lower in the building.