Underside Of Roof Sheathing Is Wet

Mold on attic sheathing.

Underside of roof sheathing is wet.

When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black. The presence of mold inside your home even if it. If the temperature drops below the freezing point often at night after the sun goes down this moisture will freeze. Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest.

When this phenomenon occurs the sheathing or framing may become slightly wet on the surface. Does mold on attic sheathing have to be removed. The ventilation is needed not only for moisture control but also to reduce by 20 40 high summertime attic and roof sheathing temperatures which are bad for roof trusses rafters and the roof sheathing as well as the shingles and underlying waterproofing membrane which can reach 160 180 degrees over an unventilated attic. Trapped water will boil when the sun heats the roof and the shingles will then have small pits where.

There were also several issues with the intersection of the roofs where the 2 apartments meet. Generally tearing off a roof and roof sheathing and perhaps roof framing to remove mold would not be sensible nor cost justified. The sheathing at the peak of the roof was saturated with moisture. This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood.

Mold growth provided it is not just cosmetic mold which can simply be left alone can be cleaned from wood surfaces by blasting scrubbing or even simple surface wiping depending on the surface accessibility and. This occurs when the temperature of the sheathing drops below the dew point creating a thin layer of moisture on the substrate. On going back inside the attic the frost had melted and the underside of the sheathing was wet not so much that it was dripping but enough that it was damp. Mold growing on the sheathing in your attic is a serious problem that shouldn t be ignored.

Those often are the underside of the roof. The following picture is of a long standing moisture condition in an attic where much of the roof sheathing has turned black. It is never a good idea to install a roof over wet plywood or any type of roof sheathing.