Filter
Top Products
38
12
12
Finishing
A. Non-Combustible Materials
• Materials which will not ignite and burn, composed of any
combination of the following:
- Steel - Iron
- Brick - Tile
- Concrete - Slate
- Glass - Plasters
• Materials reported as passing ASTM E 136, Standard
Test Method for Behavior of Metals, in a Vertical Tube
Furnace at 750° C
B. Combustible Materials
• Materials made of or surfaced with any of the following
materials:
- Wood - Compressed paper
- Plant fi bers - Plastic
• Any material that can ignite and burn; fl ame proofed or
not, plastered or un-plastered
74 in.
(1880 mm)
50 in.
(1270 mm)
12 in.
(305 mm)
12 in.
(305 mm)
Figure 12.1 Hearth Extension Dimensions
Table 12.2
C. Hearth Extension
WARNING! Risk of fi re! High temperatures, sparks, em-
bers or other burning material falling from the fi replace may
ignite fl ooring or concealed combustible surfaces.
• Metal hearth strips MUST be installed (Section 7.C.).
• Hearth extensions MUST be installed exactly as
specifi ed.
Table 12.1
Hearth Extension Insulation Alternatives-Total minimum R Value must equal 2.32
Material
k per inch
thick
R per inch
thick Minimum thickness required
Hearth & Home HX3, HX4 (Micore 300™) 0.49 2.06 1 in. (25.4 mm)
USG Micore 160™ 0.39 2.54 1 in.(25.4 mm)
USG Durock™ Cement Board 1.92 0.52 4 in. (101.6 mm)
Cement Mortar 5.0 0.20 10 in. (254 mm)
Common Brick 5.0 0.20 10 in. (254 mm)
Ceramic Tile 12.50 0.08 25-3/4 in. (654 mm)
Armstrong™ Privacy Guard Plus 0.46 2.18 1 in. (25.4 mm)
Marble 14.3 to 20.0 0.07 to 0.05 29-1/2 to 41 in. (749.3 to 1041.4 mm)
R = 1/k x inches of thickness
• You MUST use a hearth extension with this fi replace.
• This fi replace has been tested and approved for use with
a hearth extension insulated to a minimum R value of
2.32.
• 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 12.1 to convert a k
value to an R value,
• Refer to Table 12.2 for hearth extension insulation
alternatives.
(R value of hearth must be
equal to or greater than 2.32)
Heat & Glo • RUTHERFORD-50 • 4059-333 Rev C • 06/08