FIREPLACE INSTALLATION
*HEARTH EXTENSION EQUIVALENTS
Hearth extensions are made of a 1/2" thick piece of **MICORE CV230 fiberboard covered with a sheet of 26 gauge galvanized steel. You may purchase these materials locally to fabricate hearth extensions. You can construct hearth extensions from any noncombustible material that is 1/2" thick with a “K” value (thermoconductivity) of 0.43 or lower.
For example, an insulating material 1/2" thick with a “K” value of 0.35 would be acceptable. A hearth extension made from materials 1/2" thick with a “K” value of 0.43 or lower is equal to the H1652 or H2066 hearth extensions. See Figure 8, page 10.
**MICORE CV230 is manufactured by U.S. Gypsum Corporation. The following relations could be useful:
C = K divided by the material thickness (Example C = .43 divided by 1/2 (.50)
C = .86)
K = C multiplies by the material thickness (Example K = .86 multiplied by 1/2 (.50)
K = .43)
R = The material thickness divided by K (Example R = 1/2 (.50) divided by .43
R = 1.16)
C = Thermal Conductant
R = Thermal Resistance
WARNING
Only install metal safety strip horizontal to the fireplace.
Fireplace
16"min. - 400 unit 20" min. - 500 unit
8"
8"
Metal
Safety Strip
Figure 9 - Installing Hearth Extension and Metal Safety Strip
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