Face nailing, which is also called direct nailing, means nailing a nail directly into the face, or flat part of the piece of wood or material, at a perpendicular angle to the material into which the nail will sink. In face nailing, the head of the nail is always left exposed, and is not counter-sunk.
Where Face Nailing is Used
Face nailing is often seen in outdoor decks, where the nail heads which had been driven into the wood are visible. In an outdoor setting, when face nailing, always be sure to used galvanized nails so that there will be no rusting of the nail heads.
In laying floors in the tongue and groove board method, the edges of the floor are often direct nailed or face nailed, rather than glued. Though there is preference between different floor installers, generally it is felt that the floor boards around the perimeter of the room which have had face nailing instead of gluing will last longer without coming loose.
The disadvantages of face nailing in this situation is merely one of esthetics, the face that you can see the nail heads.