Attic nails

(Christopher Foley) #1

Ive seen roof shingle nails get rusty due to poor ventilation - as this attic had lousy ventilation, but never black and the sheathing turn black around the nail.
Roof is new (5 yrs) over an old layer.
Would this be mold starting at each nail site ?, and is this black nails due to poor ventilation or old roof leaking at all the nail penetrations?

(Kenneth A. Ramm) #2

More like chemical discoloration due to high humidity frost.

(Roy Lewis, CMI - North Florida Inspector) #3

It rained a few time before they dried it in.

(Bradley K. Toye, CMI) #4

Huh? That makes no sense at all. Those are shingle nails…already dried in Roy.

Chemical discoloration from chronic sweating nails. The nails could be the cheaper electroplated type. I see this in cedar siding too when they don’t use a recommended nail type.

(Christopher Foley) #5

Thanx guys, knew it was due to lack of ventilation but never saw them black before. Get the Brasso out and shine away.

(Roy Lewis, CMI - North Florida Inspector) #6

My bad…

(Michael A. Clark, CMI) #7

They used old steel nails from grandpa’s coffee can.

Today most roofing nails are galvanized and won’t rust like that.

(Marcel R. Cyr, CMI) #8

Well, whether it is the right nail or wrong nail, moisture is needed to rust out the nails. Usually caused by moisture, even galvanized nails will rust and condensation will darken the plywood penetration.

From the look of the second picture of the OP, it appears that the soffit ventilation is blocked and not allowing the proper ventilation to prevent this.