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IMPORTANT! Hearth extension design must be determined
before installation of fi replace.
Floor
Noncombustible
Framing Material
Noncombustible
Finishing Material
Protective Metal
Hearth Strips
1 in. Micore or
equivalent insulation
& 1/2 in. Durock
Bottom of
fireplace opening
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.
Platform must be built
to raise the bottom of
the fireplace opening
to the level of the
desired hearth height.
20 in. Min.
Hearth Extension
Figure 12.3 Raised Platform Hearth Extension Detail
Raised Hearth Extension Framing
The hearth framing must be constructed of non-combus-
tible materials (Figure 12.2) and placed on 1/2 in. Durock
and 1 in. Micore (or equivalent material) (Figure 12.4).
When creating the platform, allow for the thickness of the
non-combustible fi nishing materials (Figure 12.5).
Noncombustible
Framing Material
1 in. Micore or
equivalent insulation
& 1/2 in. Durock
Figure 12.4 Raised Platform Hearth Extension-Framing Materials
Noncombustible
Finishing Materials
Figure 12.5 Raised Platform Hearth Extension-Finishing Materials
* 2 in. (51 mm)
Continuous,
non-combustible sealant
Tile, stone or other
non-combustible material
Floor constructed of wood or
other combustible material
1 in. Micore or
equivalent insulation
(see Table)
Fireplace
Protective
Metal Hearth
Strip
Durock
*
*
Figure 12.2 Hearth Extension Construction
Heat & Glo • RUTHERFORD-42 • 4059-309 Rev G • 11/08