Black soot in Attic any Ideas.

I was wondering if any one could guess what the black soot like substance could be in an attic I inspected. It was all over the roof sheeting and laying in th insulation near a clothes dryer vent stubbed into the attic.The pictures arent that great but I am just looking for opinions.Thanks in advance

First, dryers should not vent into attics (can you say moisture problem?)
Was there a fire in the dryer? I would be more concerned with the venting itself than the black gookus. Could be lint from black clothes.
Not to mention incorrect dryer vent material.
Could be mold from moisture in the attic from (see above)

my guess would be mold/mildew caused by that stupid dryer vent location…that is just wrong…jim

Are you sure that was the dryer? It should not be in the attic to start with. Second if it is the dryer the vent pipe should not be that plastic vent pipe.

2nd Picture is the vent stack for the drain which looks like it is leaking check the boot for cracks

Agree. My guess would be water staining. If that is a dryer vent, they’re going to end up having major mold issues with it venting there. Even if it was a bath vent it should still vent outside.

This looks like a combination of things to me. A leaking plumbing vent flashing boot, poor or no soffit ventilation, and the termination of the “dryer” vent, resulting in mold/mildew.

Just curious do see alot of PVC for vent stacks. I always see abs. The main issue looks like it is with the vent stack, curious if not a properly installed flange if not indeed cracked. Obviously the dryer should be vented to the outside, but also looks like there is no air dams or space for the soffit to contribute to proper ventilation for the attic.

With the limited information provided, the soot stains you are referring to appears to be an unknown type of mold on the surface, underside of the roofs sheathing membrane and on the surface of the trusses (does not appear to be soot and should not be referred as soot but should be referred as “an unknown type of stain”, if not known exactly). However, you did not mention if the home has a free standing solid fuel burning appliance or open masonry fireplace, if so, the chimney (masonary or factory built type entering through the attic), could be unknowingly defective.
Further, I noted in a few of the photos that there appears to be no venting material installed between the ends of the trusses (above the exterior wall frame and into the roofs soffits), this could be a contributing factor (mold stains) as there could be inadequate venting within the attic (blown insulation insulation covering vent openings?).
As to the dryer vent (assuming to be, could be a bath vent), it should be replaced with an 4 inch rigid smooth pipe with the vent pipe in the attic insulated as the attic is an unheated space and terminated to the exterior of the home with a vent cover.
Further, agree that the plumbing vent stacks flashing should be checked for possible defects.

Dave Brice CMI, RHI
Pacific West Home Inspections