A self-drilling fastener for use in a friable material with or without an
underlying member at the point of use comprises an elongated body, a
threaded exterior, an enlarged head with torque transmitting surfaces,
proximal, intermediate, and distal portions, and a drilling tip generally
opposite enlarged head. Proximal portion has an axial length, a threaded
exterior having root and crest diameters and a thread height, where the
crest diameter is about twice the root diameter. Intermediate portion has
an axial length, a threaded exterior having a root, a crest diameter
substantially smaller than proximal portion crest diameter and a thread
height substantially smaller than proximal portion thread height. Distal
portion has an axial length, a threaded exterior with a root that tapers
toward the drilling tip, a crest diameter substantially smaller than the
proximal portion crest diameter, and a thread height substantially
smaller than the proximal portion thread height portion.