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9.2.5
Installation Raised of 4" (102 mm) and Less
If non-combustible material floor protection needs to be added in front of and level with the
hearth extension of the masonry fireplace (F = 4" [102 mm) or less), an R-value equal to or
greater than 1.00 is required and should extend at least 22" (560 mm) in front of the unit (B).
Refer to
«Figure 12: Additional Floor Protection - Not Raised Installation»
9.2.6
Installation Raised of More Than 4" (102 mm)
If the extension of the masonry hearth is raised at least 4" (102 mm) from the floor protection, a non-
combustible material, without an R-value, must extend at least 16" (406 mm in USA) or 18" (457 mm
in Canada) in front of the unit (B). Refer to
9.2.7
R Value
There are two ways to calculate the R-value of the floor protection. First, by adding the R-values of
materials used, or by the conversion if the K factor and thickness of the floor protection are given. To
calculate the total R value from R values of the materials used, simply add the R-values of materials.
If the result is equal to or greater than the R-value requirements, the combination is acceptable.
R-values of some selected materials are shown below :
Table 6 : Thermal Characteristics of Common Floor Protection Materials
MATERIAL
Micore® 160
Micore® 300
Durock®
Hardibacker®
Hardibacker® 500
Wonderboard®
Cement mortar
Common brick
Face brick
Marble
Ceramic tile
Concrete
Mineral wool insulation
Limestone
Ceramic board (Fibremax)
Horizontal still air
(⅛"thick)
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Example:
Required floor protection R of 1.00. Proposed materials: four inches of brick and one inch of
Durock® board.
Four inches of brick (R = 4 x 0,2 = 0,8) plus 1 inch of Durock® (R = 1 x 0.52 = 0.52).
This R value is larger than the required 1.00 and is therefore acceptable.
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Information as reported by manufacturers and other resources
18
Horizontal still air can't be «stack» to accumulate R-values; each layer must be separated with another non-combustible material.
Installation and Operation Manual - Destination 2.7 Insert
«Figure 11: Additional Floor Protection - Raised
CONDUCTIVITY (K)
PER INCH
0.39
0.49
1.92
1.95
2.3
3.23
5.00
5.00
9.00
14.3 – 20.00
12.5
1.050
0.320
6.5
0.450
0.135
0.8 + 0.52 = 1.32.
RESISTANCE (R) PER INCH
THICKNESS
2.54
2.06
0.52
0.51
0.44
0.31
0.2
0.2
0.11
0.07 – 0.05
0.008
0.950
3.120
0.153
2.2
0.920**
Installation».
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Page 33
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