I was asked about this by a contractor, sorry no pictures.
Does anyone have any ideas why this would occur on a 4 year old townhome?
The attic insulation looks normal on top and good down 6 inches with typical pink blown in insulation. The lower 6 inches or so is much darker with shades of brown and dark gray.
Also the baseboards have some of this darker insulation oozing out along the edges. Nothing looked unusual in the hvac filters.
Original owner and no past history of leaks or mold or anything unusual.