Most builders fail to read the mounting instructions when installing pull down stairways leading up to the attic. They are most often found installed with sheet metal screws which do not have the sufficient side to side sheer strength.  Most installation decals found on the inside of the ladder require a minimum of 16 16D nails that should be applied to all sides of the ladder. This can be a safety issue when carrying boxes or large items up the ladder to store in the attic. 

Franklin_TN_Pull Down Stairway