Black Stains On Plywood In Attic

While the black stains are either mould or just black dust from attic insulation settled on the.

Black stains on plywood in attic.

First let s look at the source. Attic feels excessively hot or stuffy attics should feel breezy if they are properly ventilated. I have obvious moisture stains in the attic and the roof. In winter moist air is transported from the heated area of the home into the unheated attic space where it not only settles on the wooden rafters and plywood roof sheathing but also melts the snow on the roof leading to ice dams.

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. When moisture condenses on plywood roof sheathing repeatedly or continuously the wood will turn black. I m aware of the cause poorly vented bathroom fans and not well sealed fan fixtures lights wires etc. This type of mold growth will not smudge or wipe off.

If the dark surface of the wood smudges it could be mold. In old houses you ll usually see some spots that are stained dark or black where there was a roof leak at some point in time which was repaired but the stain remains. Notice the dark staining in the first picture. If the wood is soft if it s easily imprinted when you push on it it s probably rotten.

This summer i cleaned the portion of the black stain with a dry mop as much as i could reach from the hatch opening. This can be caused by the action of fungal growth and molds and the affect they have on the tannins in the wood. 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. You can remove small amounts of mold covering 10 square feet or less of attic sheathing yourself but if the mold growth covers more than 10 square feet you should contact a.

Some spots are just patches here and there and others are big areas. You have mold that should be removed. I have surface mold on the sheathing in my 1982 vintage 12 6 pitched attic. Black mold in attics.

Last winter i took a look into the attic and noticed black stains and water marks on a portion of the sheathing material. Often this is a sign that the plywood has been replaced recently.