
Heat & Glo • RH-36/RH-42 • 4044-153 Rev U • 11/07
29
Fire Risk
• Metal hearth strips MUST be installed.
Sparks or embers may ignite
fl
ooring.
WARNING
Figure 8.2 Place Metal Hearth Strips
Metal Hearth Strips
Metal hearth strips are placed 2 in. (51 mm) under the front
of the
fi
replace and must extend beyond the front and sides
of
fi
replace opening by 2 in. (51 mm). The metal strips must
overlap by 1 in. (26 mm) minimum.
Hearth Extension
If not using an HX3 or HX4 hearth extension, refer to Sect.
A and Table 8.1 for substitute material.
HX3 or HX4
Figure 8.3 Hearth Extension, HX3 or HX4
The hearth extension must be covered with non-combustible
materials as illustrated below in Figures 8.4 and 8.5.
• Non-Combustible
Materials
Material which will not ignite and burn. Such materials
are those consisting entirely of steel, iron, brick, tile, con-
crete, slate, glass or plasters, or any combination there-
of.
Materials that are reported as passing ASTM E 136,
Standard Test Method for Behavior of Materials in a Ver-
tical Tube Furnace at 750° C, shall be considered non-
combustible materials.
• Non-Combustible Sealant Material:
Sealants which will not ignite and burn; Rutland, Inc.
Fireplace Mortar #63 Rutland 76R, Nuflex 304, GE
RTV106 or GE RTV116 (or equivalent).
4 in. (102 cm)
minimum
HX3 or HX4
covered with
non-combustible
facing
See Figure 5
for detail
Figure 8.4 Hearth Extension
2 in. (51 mm)
required
High temperature
(300°F min.) continuous,
non-combustible sealant
Tile, stone or other
non-combustible material
Floor constructed of wood or
other combustible material
HX3 or HX4
Hearth Ext
or equivalent
insulation
(see Table below)
Fireplace
Protective
Metal Hearth
Strip
Figure 8.5 Hearth Extension Detail
Fire Risk
• Hearth extensions must be installed
exactly as speci
fi
ed.
High temperatures or hot embers may ignite
concealed combustibles.
WARNING