Method of assembling roof decking to an underlying substrate

A method of assembling roof decking to an underlying substrate by using a fastener-driving tool for driving fastener pin-washer assemblies into said underlying substrate, comprising the steps of:

• providing a pin having a head having a predetermined outer diameter;
• a tapered shank defining a predetermined conical angle and having a smaller end and a larger end;
• a point joined unitarily to said smaller end of said tapered shank and conforming substantially to an ogive;
• and a transition zone having a small end joined unitarily to said larger end of said tapered shank and a large end joined unitarily to said head;
• mounting a washer upon said tapered shank of said pin at an axial position spaced from said head of said pin, wherein said washer has a predetermined outer diameter which is substantially the same as said predetermined outer diameter of said head of said pin so as to cooperate with said head of said pin in axially guiding said pin as said pin is axially driven through a fastener-driving tool, wherein said washer remains intact so as to engage said roof decking after said pin is driven into said substrate by the fastener-driving tool so as to secure said roof decking to said substrate and maintain said roof decking secured to said substrate, and wherein further, said washer comprises an annular periphery and a central aperture, said central aperture having a margin defined by a plurality of concave, pin-engaging surfaces spaced angularly from one another, wherein each pin-engaging surface conforms essentially to a cylindrical section, and wherein further said pin-engaging surfaces collectively encompass less than one-half of a complete cylinder, but not less than about one third of a complete cylinder, so as to limit potential damage to said tapered shank of said pin when said washer is moved axially along said tapered shank of said pin as said pin is driven into said substrate by the fastener-driving tool;
• and
• driving said pin through said roof decking and into said substrate whereupon said washer is moved relatively with respect to, and along, said tapered shank of said pin from said axial position spaced from said head of said pin to an axial position nearer to said head of said pin so as to engage said roof decking and secure said roof decking to said substrate.