WARNING: THE HEARTH EXTENSION AND THE
METAL SAFETY STRIP SHOULD BE INSTALLED
ONLY IN A HORIZONTAL RELATIONSHIP TO THE
FIREPLACE, AS ILLUSTRATED.
METAL
SAFETY STRIP
HEARTH EXTENSIONS
FLOOR LINE WITH RAISED HEARTH
TOP OF
RAISED HEARTH
12" (MIN)
20"
(MIN)
12" (MIN)
METAL
METAL
SAFETY
SAFETY
STRIP
STRIP
58"
58"
30"
30"
74"
74"
COMBUSTIBLE
COMBUSTIBLE
FLOOR
FLOOR
59"
59"
28 1/2"
28 1/2"
20"
20"
HEARTH
PROTECTOR
F
IGURE
13
F
IGURE
12
The ability of insulating material to retard the transfer of heat may be expressed as either Thermal Conduc-
tance (C), Thermal Conductivity (K), or Thermal Resistance (R). The mathematical relationship of these
values and the formulas for converting one value to another is as follows:
C=K divided by the material thickness2
(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)
F
LOOR
P
ROTECTION
With either type hearth extension minor shifting of the supporting floor or expansion and contraction may
eventually cause a crack to develop between the hearth extension and the face of the fireplace. To help
prevent the crack from developing, the hearth extension materials must be firmly fastened in place. Wall ties
should be screwed to the face of the fireplace and imbedded in the mortar joints of brick, stone, or other non-
combustible materials. The metal safety strip packed with the fireplace must be placed beneath the fireplace
and extended under the hearth extension or into a mortar joint of the hearth extension as shown by Figures 10,
12, and 13. In the event a crack does eventually develop, the metal safety strip will serve as a barrier to
prevent sparks or embers from falling from the fireplace onto combustible flooring materials.
10
53D9037. Rev 1 03/03
Summary of Contents for Radiant Wood Burning HWB800HB
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