August 3, 2015
7063-513E
11
VOYAGEUR
C. Calculating Alternate Floor Protection
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 material 1 inch thick
for each degree (F) of temperature difference from one side of
the material to the other.
The LOWER the k factor means less heat is being conducted
through the non-combustible material to the combustible material
beneath it.
The k value of a material must be equal or smaller then the re-
quired 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, whereas you can
not do this for k value.
The HIGHER the R factor means less heat is being conduct-
ed 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.
Converting k to R:
Divide 1 by k and multiply the results times the thickness in inch-
es of the material.
R = 1/k x inches of thickness
Converting R to k:
Divide the inches of thickness by R.
k = inches of thickness/R
Calculations:
Example: Floor protection requires k value of 0.84 and 3/4 inch
thick.
Alternative material has a k value of 0.6 and is 3/4 inch thick.
Divide 0.6 by .75 = k value of 0.80. This k value is smaller than
0.84 and therefore is acceptable.
