A parge coat is a thin coat of a cementitious or polymeric mortar applied to concrete or masonry for refinement of the surface.
Parging (or pargeting) is usually applied with a trowel and pressed into the existing surface. The intent is to create a contiguous surface by filling surface air voids and bugholes (eliminating bughole-induced outgassing), to level a surface with extreme rugosity, or to prep a surface for topcoating with a high-performance protective coating.
Parging is a low-cost alternative to repointing, providing structural cohesiveness to masonry walls whose mortar has begun to fail. Parge coating can also be used to create air tightness for apartments.