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10
Floor Protection
All woodstoves require floor protection when installed on a
combustible surface. You must place use protector
equivalent to 3/8' asbestos millboard covered with 24
gauge metal. The floor protector must extend 16" in front of
the door side, 8" on each side and 8" in the rear of the unit
and under the chimney connection and 2" beyond each
side. See Figure 4.
The k, C or R factor that correlates with the floor protector
material used during the test if the room heater is not
provided with a floor protector. The units of measure for k,
C and R factors shall use the same applicable units.
Directions and examples on how to use alternate materials
and how to calculate equivalent thickness shall be shown.
An easy means of determining if a proposed alternate floor
protector meets requirements listed in the appliance
manual is to follow this procedure:
1. Convent specifications to R-value
a. R-value is given - no conversion is needed.
b. K-factor is given with a required thickness (T) in
inches: R=1/k+T
c. C-factor is given: R=1/C
2. Determine the R-value of the proposed alternate floor
protector.
a. Use the formula in step 1 to convert values not
expressed as “R”.
b. For multiple layers, add R-values of each layer to
determine the overall R-value.
3. If the overall R-value of the system is greater than the R-
value of the specified floor protector, the alternate is
acceptable.
EXAMPLE:
The specified floor protector should be 3/4 inch thick
material with a k-factor of .84.
The proposed alternate is 4" brick with a C-factor of 1.25
over 1/8" mineral board with a k-factor of .29.
Step 1: Use formula above to convert specification to
R-value. R=1/kT = 1/0.84 x .75 = .893
Step 2: Calculate R of proposed system.
4" brick of C - 1.25, therefore
R brick = 1/C = 1/1.25 = 0.80
1/8" mineral board of k+ 0.29, therefore
R min.bd. = 1/0.29 x 0.125 = 0.431
Total R = R brick + R brick + R mineral Board
= 0.8 + 0.431 = 1.231
Step 3: Compare the proposed system R of 1.231 to
specified R of 0.893. Since proposed system
R is greater than required, this is acceptable.
Definitions:
Note: Asbestos cannot be used. Asbestos is used as a
standard only. 3/8 inch asbestos millboard has a “K” factor
of 0.84. The newer substitute CERAFORM board has a “K”
factor of 0.21. Your floor protector must have an equivalent
or better “K” factor than the above recommendations.