A.Michael Byrne
responds: ANSI (American National Standards
Institute) specifications require that a
corrosion-resistant roofing nail be used when
nailing tile backerboard, and that the nail
penetrate the wood framing at least.
3/4 inch. While there are no direct references
to pneumatic nailing, I see no reason why pneumatic
roofing nails couldn’t be used, as long as
the fasteners were of sufficient length.
It’s important that the nail head does not
break the fiberglass matting material imbedded in
the backerboard, so make sure to properly set both
the gun’s depth adjustment and the air
pressure.
Corrosion-resistant screws can also be used,
providing their head diameter is large enough to
resist a 125-pound pull-through force. Hi-Lo S
Rock-On screws (ITW Buildex, 1349 W. Bryn Mawr
Ave., Itasca, IL 60143; 800/323-0720) meet this
requirement.
Backerboard installed over a plywood subfloor
should always be fully bedded in mortar or
adhesive. In these situations, many contractors
mistakenly think that the fasteners serve as clamps
and that their holding power is not an issue after
the mortar or adhesive "grabs." But the primary
function of the setting bed is to provide a
leveling bed for the backerboard; the fasteners are
what holds the backerboard in place for the life of
the tile installation.
For detailed guidelines on tile installation
requirements, contact the Tile Council of America
(P.O. Box 1787, Clemson, SC 29631; 864/646-8453)
for a copy of the Handbook for Ceramic Tile
Installation.
A tile contractor for more than 20 years,
Michael Byrne is now director of
the Ceramic Tile Education Foundation in Clemson,
S.C.