New Buck Corporation 85 Instruction Manual page 16

ALTERNATE FLOOR PROTECTORS MATERIAL
Floor protector must be 3/8" minimum thickness non-combustible material or equivalent.
With the floor protector or hearth extension material specified as one layer of 2" thick brick
with a K* factor of 5.0, you may use alternate materials as long as the K* factor (s) is calculated
as follows:
FORMULA:
Required thickness = (K of alternate material/K of millboard) X (thickness of millboard)
EXAMPLE:
An alternate inorganic non-combustible millboard with a K* of .9375 would require a
thickness as follows:
K* FACTORS OF ALTERNATE MATERIALS
Material
Ceroform 126
Limestone
Concrete
Sandstone
Marble
Hearth extension or floor protector thickness above four (4) inches are generally not acceptable
due to cost, floor load capacity and look. The alternate we recommend is using Ceroform No.
126 millboard 1/8" minimum and putting any type decorative brick or stone (any thickness) on
top of it.
* The K* factor represents thermal conductivity of a material and is time rate of heat flow
through a homogeneous material under steady-state conditions, through unit area, per unit
temperature gradient in the direction perpendicular to a surface.
Required thickness = (.9375/5.0) x 2 in.
= 3/8 inch
K
.21
8.0
8.0
13.0
18.0
Page 14
Required Thickness
1/8"
3.2"
3.2"
5.2"
7.2"