CW2500 Insert Installation and Operation Manual
30
To calculate the total R factor from R factors 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. To know the R-values of some selected materials, see table
Thermal Characteristics of Common Floor Protection Materials.
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).
0.8 + 0.52 = 1.32.
This R value is larger than the required 1.00 and is therefore acceptable
In the case of a known K and thickness of alternative materials to be used in combination,
convert all K values to R by dividing the thickness of each material by its K value. Add the
R values of your proposed materials as shown in the previous example.
Example:
K value = 0.75
Thickness = 1
R value = Thickness/K = 1/0.75 = 1.33
Data for Floor Protection Calculation lowered at least 8" (F) from the hearth
extension
MINIMUM
EXTENDED
A
B
C
D
E
F
AIR
JACKET
INCHES
Dimension of
the hearth
extension
CAN: 18"
USA: 16"
0"
D = B - (A - C)
12 1/8"
8"
Flush with
fireplace
facing
MILLIMETRES
CAN: 457 mm
USA: 406 mm
0 mm
D = B - (A - C)
308 mm
203 mm