FLOOR PROTECTION
The ability of insulating material to retard the transfer of heat may be expressed as either Thermal Conductance (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 thickness (Example C = .43 divided by 1/2 (.50)
C = .86)
53 1/8"
FIGURE 13
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)
26 3/8"
52 7/8"
27"
METAL SAFETY STRIP
COMBUSTIBLE
FLOOR
20"68"
WARNING: THE HEARTH EXTENSION AND THE
METAL SAFETY STRIP SHOULD BE INSTALLED
ONLY IN A HORIZONTAL RELATIONSHIP TO THE
FIREPLACE, AS ILLUSTRATED.
FIGURE 14
12" (MIN)
TOP OF
RAISED HEARTH
12" (MIN)
FLOOR LINE WITH RAISED HEARTH
20" (MIN)
METAL
SAFETY STRIP
HEARTH EXTENSIONS
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 11, 13, and 14. 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.
11
53D9028. Rev 1 03/03
