alot of old 1x decks have alot of nails that hit cracks. theese nails can and will back up.
but for the most part if you have alot of backed up nails then they were probably naever nailed hard enough in the first place. if so you can pound them down and put a little sealant inbetween shingle, over nail.
ringshank roofing nails are starting to take over.
they hold like hell.
i will be charging extra to tear off roofs with
ringshanks.
tore one off recently and had to leave the ringshanks cause it was tearing apart the decking trying to get them out.
you have to take them out one by one with hammer.
gweedo.