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.
Rusty nails in attic.
Roof is new 5 yrs over an old layer.
Once you have the humidity in your house under control repair the worst of the drywall nail pops apply a stain blocking primer to the walls and ceilings to cover the rust stains and topcoat with latex wall and ceiling paint.
Moisture causes metal components of the roof like nails to rust and potentially break which can lead to shingle loss.
Is this a sign of poor ventilation in the winter.
Excessive attic moisture condenses on the cool metal surface of the roofing nails causing corrosion or rust on the nails and stains on the surrounding wood materials.
Stains on the insulation and rusty nails above the stains in the roof sheathing.
If you find this then you need to look further into improving your attic ventilation performance.
All of those things will add to the moisture in the attic and will rust any metal exposed there.
Power attic vents may be needed if humidity is too high in the attic.
Without consistent air flow in your attic moisture will linger and begin to rot the wood which can result in roof damage.
Roofing nails are galvanized but add enough moisture and galvanized nails will rust.
Check inside your attic for mold stains and rusty nails.
These same condensation points the roofing nails will often map exactly the drip stains found on the attic insulation or attic floor below each nail.
Indications that your attic might have a ventilation problem include wet or compressed insulation rusty nails or rust spots that dripped onto your insulation blackened plywood mold or mildew inside your attic curling or cracking shingles uneven snow melt and icicles at the roof edge.
To create rusty nails you can use hydrogen peroxide vinegar and salt to rust your nail or you can.
These nails are rusting due to the living area heat breaching up through the ceilings and into the attic cavities during the winter months from inadequate insulation.
I found these signs in an attic today.
Usually rusty nails are something that people try to avoid but there are certain circumstances where you d want a nail to be rusty.
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.
As a last resort install a dehumidifier.