Source : Webster's Revised Unabridged Dictionary (1913)

Waterproofing \Wa"ter*proof`ing\, n.
   1. The act or process of making waterproof.

   2. Same as {Waterproof}, n., 1.

Source : WordNet®

waterproofing
     n 1: the act of treating something to make it repel water [syn: {sealing}]
     2: a coating capable of making a surface waterproof