Black spots on fiberboard in basement...Possible Mold?

[Matt Butcher]

Does anyone know what this material is? It was behind a stud wall in the basement against the concrete foundation walls. There appears to be a slight gap behind the sheathing, so I don't think they are concrete forms left in place. Any help would be greatly appreciated!

[Rick K. Kie]

My first impression is homosote with mold on it. Texture tells a lot and that can't be told by the pictures to me.

[Matt Butcher]

I thought it might be mold at first, (which it still very well could be), but it was uniform over the wall in all the areas I could view in both the basement and in the attic. Thought it might be some sort of asphalt impregnated sheathing, but I am open to any thoughts/answers otherwise. Thanks again!

[Peter Doane]

Did you try to wipe it off?? If its surface mold you would be able to smear it... To me it looks like some form of impregnated sheathing. Fibers look to uniform to be an organic growth.... Just my two cents.

[Dennis R. Goudreau]

Originally Posted by pdoane

Did you try to wipe it off?? If its surface mold you would be able to smear it... To me it looks like some form of impregnated sheathing. Fibers look to uniform to be an organic growth.... Just my two cents.

I agree Pete to consistent in shape & depth by what I can see