31
Heat & Glo • Rutherford 42-B Installation Manual • 4059-712 • Rev O • 09/28/15
2. Raised Hearth Extension and Raised Fire-
place
Non-combustible flooring a minimum of 20 in. (508 mm)
in front of and 12 in. (305 mm) to each side of the fuel
opening is required.
The hearth framing must be constructed of non-com
-
bustible materials (such as metal framing or equivalent
material) and placed on HX3(s) or HX4(s) and 1/2 in.
Durock, or equivalent material. Refer to Figure 7.9.
When creating the platform, allow for the thickness
of the non-combustible finishing materials
.
Seal gaps between the hearth extension and the front
of the fireplace with a bead of non-combustible sealant
or grout.
Note:
The bottom of the fireplace opening is 3-3/4 in. (95.3mm) above the bottom of the
fireplace. Finished hearth must NOT extend above this level.
Bottom of
fireplace opening
Platform must be built
to raise the bottom of
the fireplace opening
to the level of the
desired hearth height.
Protective Metal
Hearth Strips
Floor and platform constructed of
wood or other
combustible
material
Continuous,
non-combustible sealant
Tile, stone or other
non-combustible finishing
material
Non-combustible
Framing Material
1 in. Micore or
equivalent insulation
& 1/2 in. Durock
20 in. minimum
Hearth Extension
Figure 7.9 Raised Hearth Extension and Fireplace Framing Materials
