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Escape 1800-I Insert Installation and Operation Manual
35
8.4.2 Installation raised more than 5"
If the extension of the masonry hearth is raised at least 5" (127 mm) from the floor protection
(F), a non-combustible material without an R value must extend at least 16" (406 mm USA)
or 18” (457 mm Canada) in front of the unit (B).
8.4.3 R Value
There are two ways to calculate the R factor 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 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 R
values of your proposed materials as shown in the previous example.
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