Hearth Extension, Building And Finishing - Majestic Ashland ASH42 Series Installation Manual

B. Hearth Extension, Building and Finishing
WARNING! Risk of Fire!
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
Majestic Ashland Series • ASH42 Installation Manual • 4059-915 • Rev M • 07/20
High temperatures, sparks, em-
k per inch r per inch thickness
thick thick
0.49 2.06
0.49 2.06
1.92 0.52
5.0 0.20
5.0 0.20
12.50 0.08
0.46 2.18
14.3-20.0 0.07-0.05 29 1/2 - 41 1/4 in.
12 in.
(305 mm)
(1676 mm)
Figure 7.4
Minimum
required
1 in.
1 in.
4 in.
10 1/2 in.
10 1/2 in.
25 3/4in.
1 in.
42 in.
12 in.
(1067 mm)
(305 mm)
66 in.
Hearth Extension Dimensions
Surfaces must be
covered with non
combustible material
20 in. (508 mm) Minimum
29