Hearth Extension, Building And Finishing - Heatilator BIR42-B Installation Manual

B. Hearth Extension, Building and Finishing
WARNING! Risk of Fire! High temperatures, sparks, em-
bers or other burning material falling from the fireplace may
ignite flooring or concealed combustible surfaces.
• Protective metal hearth strips MUST be installed.
• Hearth extensions MUST be installed exactly as
specified.
A hearth extension must be installed with all fireplaces to
protect the combustible floor in front of the fireplace from
both radiant heat and sparks.
• You MUST use a hearth extension with this fireplace.
• Refer to Figure 7.4 for minimum dimensions.
• This fireplace has been tested and approved for use with
a hearth extension insulated to a minimum R value of
2.06.
• The hearth extension material MUST be covered with
tile, stone or other non-combustible material.
• Manufactured hearth materials will usually have a
published R value (resistance to heat) or k value
(conductivity of heat). Refer to the formula in Table 6.1
to convert a k value to an R value,
• Refer to Table 6.2 for hearth extension insulation
alternatives.
Table 6.1
R = 1/k x inches of thickness
Table 6.2
Hearth Extension Insulation Alternatives, R Value = 2.06
Material
Hearth & Home HX3, HX4
USG Micore 300™
USG Durock™ Cement Board
Cement Mortar
Common Brick
Ceramic Tile
Armstrong™ Privacy Guard Plus
Marble
Heatilator • Birmingham 42-B Installation Manual • 4059-715 • Rev P • 09/28/15
Minimum
k per inch r per inch thickness
thick thick required
0.49 2.06
0.49 2.06
1.92 0.52
5.0 0.20 10 1/2 in.
5.0 0.20 10 1/2 in.
12.50 0.08 25 3/4in.
0.46 2.18
14.3-20.0 0.07-0.05 29 1/2 - 41 1/4 in.
12 in.
(305 mm)
66 in.
(1676 mm)
Figure 7.4 Hearth Extension Dimensions
1 in.
1 in.
4 in.
1 in.
42 in.
12 in.
(1067 mm)
(305 mm)
20 in. (508 mm) Minimum
Surfaces must be
covered with non
combustible material
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