mg wrote in
:

There are 6 or 8 spiral nails on our deck that will not stay down. The
boards are flat on the deck and do not appear to be cupped or warped.
But, within about 3 months of driving the nails down, they are back
up.

Should I pull the nails and replace them with the next size larger
spiral nail?

Should I pull the nails and replace them with coated deck screws?

If you want to stay with nails then use 16d spirals in new holes. My guess
would be the deck joists are soft or chewed at that spot. Are the
particular ones even hitting a joist? Take a gander underneath (aka crawl
and get really dirty) if you really want to know. If it appears the nail is
not biting and it's not for a goofy reason like they're 8d's, you could
sister or scab a PT 2x4 on the existing joist and renail.