So many times during a home inspection we find the pull down attic stairs not installed properly. This topic is the use of screws vs 16d nails as required. Most screws are not designed for sheer strength and can break without any notice leaving you on the floor or hanging above it.
Below is part of a sample installation instruction sheet:
PERMANENT MOUNTING OF STAIRWAY B. Nail the sides (jambs) of the stairway frame to the rough
opening frame, using 16d nails or 3" lag screws. Holes
are provided in the pivot plates and piano hinge brackets.
Also nail through the end boards into the rough opening
headers. Complete permanent installation by using 16d
nails or 3" lag screws to secure stairway frame on all four
sides of the rough opening
This illustration shows what the manufacturer recommends. In this case, the the screws installed were right next to the warning label