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IN – FIELD APPLICATION
A. MIXING MORTAR FOR FIRE ROCK INSTALLATION
The mortar used when installing the Fire Rock fireplace and chimney system is available
from your Fire Rock dealer or distributor, the same dealer that sold you the Fire Rock
system.
This specially formulated mortar is low sand, polymer modified with heat resistant
additives and is designed to work as a “glue” rather than a typical joint provider.
This mortar must be used for your Fire Rock Warranty to be valid.
It is appropriate to use a trowel or grout bag to apply the mortar to firebox and smoke
chamber joints. This material is to be mixed according to the instructions on the bag and
troweled directly from the mixing pail. These joints should be completely covered and
the components stacked so as to result in a 1/16th to 1/8th inch joint and the excess
mortar should push (ooze) out and be scraped away. Use this product as an adhesive
rather than a traditional mortar, the thin coating described above (1/16th to 1/8th inches
thick) will work best.
Upon completion of the firebox and smoke chamber it is important to go back and
“butter” all joints. This procedure involves a final smoothing, inside and out, sealing all
joints and assuring a “no leak” installation.
B. FIREBRICK LINING THE FIREBOX
A 1 ¼” minimum firebrick (ASTM 1261) lining is required for an acceptable fire safety
level. The same Fire Rock mortar used for the firebox and chimney may be used to affix
the firebrick to the inner wall of the firebox. The firebrick may be installed one of two
ways.
1) Troweled joints: The mortar may be troweled on to the face of the firebrick
at a thickness of 1/16th to 1/8th inch and stuck to the presoaked inner wall of
the firebox.
2) Dipped joints: Add enough clean (suitable for drinking) water to the
mixed mortar to achieve a consistency that a typical firebrick floats with
roughly 40% of its mass above the surface. Too much water will reduce
strength.
A “brick to brick” (no mortar joints) installation will be the strongest; a mortar joint is a
weak spot.
The mortar will not develop its full strength until completely cured.
