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Heatilator • ECO-WINS18 • 7065-132D • November 22, 2011
C. Alternate Floor Protection Calculation
Material
Thermal Conductivity: k value
The k value indicates the amount of heat (in BTU’s) that
will fl ow in 1 hour through 1 square foot of a uniform mate-
rial 1 inch thick for each degree (F) of temperature differ-
ence from one side of the material to the other.
The LOWER the k factor means less heat is being con-
ducted through the non-combustible material to the com-
bustible material beneath it.
The k value of a material must be equal or smaller then the
required k value to be acceptable.
(BTU) (inch)
(foot
2
(hour) (
o
F)
Thermal Resistance: R value
The R value is a measure of a material’s resistance to
heat transfer.
R value is convenient when more than one material is
used since you can add the R values together, where-
as you can not do this for k value.
The HIGHER the R factor means less heat is being
conducted through the non-combustible material to
the combustible material beneath it.
The R value of a material must be equal or larger then
the required R value to be acceptable.
Conversion Procedure
1. Convert specifi cation to R-value
a. R-value given - no conversion needed
b. k-factor is given with a required thickness (T) in
inches. [R = 1/k X T]
c. K-factor is given with a required thickness (T)
in inches. [R = (1/K X 12) X T]
d. r-factor is given with a required thickness (T) in
inches. [R = r X T]
2. Determine the R-value of the proposed alternate fl oor
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 overall R-value.
3. If the overall R-value of the system is greater than the
R-value of the specifi ed fl oor protector, the alternate is ac-
ceptable.