Yes quite normal for roofing nails to penetrate.
Roofing nails penetrate soffit.
The condensation is caused by warm air leaking through the insulation between the top floor and the attic.
The first thing that will happen here is the application of the building paper.
The nails sticking through the roof sheathing is normal.
Use only zinc coated steel or aluminum 10 12 gauge barbed deformed or smooth shank roofing nails with heads 3 8 10mm to 7 16 12mm in diameter.
When installing roofing nails always make sure the nail is flush to the shingle.
Fasteners must be driven flush with the surface of the shingle.
Watch your head when your up there.
Roofing nails should be long enough to penetrate the roofing material and go 19 mm into osb solid wood plywood or non veneer wood decking or through thickness of decking whichever is less.
Your contractor is correct in his interpretation of the national roofing contractors association standards as well as the ohio building code which state that nails must be long enough to penetrate through all roofing materials and extend through the underside of the deck or penetrate a wood plank by of an inch even if that surface is less than inch thick.
Both these two types of nail guns pneumatic ones are run by low pressure air compressors.
Roofing nail guns can drive coil nails and don t require frequent refilling.
Fasteners should be long enough to penetrate at least 3 4 19mm into wood decks or just through the plywood decks.
To determine the nail length you should consider the number of layers of shingles shingle thicknesses underlayment and flashings installed on eaves sidewalls and valleys etc.
Now comes the roofing installation.
Roofing nails are made of galvanized steel to protect them from the elements.
Building paper can turn water if it happens to penetrate the integrity of the roofing material.
Ice dams and moisture can ruin fascia boards that run along a roof line.
A countersunk nail will rip the shingle and a nail that is not completely nailed down will eventually work its way out.
You need much more ventilation in the attic.
However siding nail guns can t drive coil nails and need several refills for long duration jobs.
It gives a roof s edge a finished look and serves as a mount for gutters.
This is a very thin black sheet that feels like a rough piece of wool.