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ALCOVE INSTALLATIONS - FLOOR PROTECTION
When the Grandview™ 230 is installed in an Alcove, the floor protection
must be a thermally rated non-combustible floor protector meeting or
exceeding a thermal rating of k=.47 or equivalent with a listed thickness
of 1/2" (12.7 mm) minimum in the USA and Canada. The thermal protec-
tion must extend 16" in front of the heater and 8" to each side (measured
from the door opening).
Using Alternate Material As Floor Protection
The floor protection or alternate material used as a floor protector must
be constructed of a durable noncombustible material having an equal or
better thermal conductivity value (lower k value) of k =.47 BTU/IN FT2 HR
°F or a thermal resistance that equals or exceeds r = 2.13 HR °F FT2 IN/
BTU with a minimum thickness of 1/2". With these values, determine the
minimum thickness of the alternate material required using the formula(s)
and shown in Table 1.
Note: Any noncombustible material having a minimum thickness of
1/2"(12.7mm) whose k value is less than .47 or whose r value is more
than 2.13 is acceptable. If the alternate material used has a higher k value
or lower r value will require a greater thickness of the material used. In
some cases, if the k value is less or the r value higher, a thinner material
may be used.
Methods of determining floor protection equivalents:
To determine the thickness required for the alternate material when
either the "k" value or "r" value is known, use either the k formula or r
formula.
Example: If Micore 160 Mineral Fiber Board is to be used for the
floor protection, how thick must this material be?
k
= k value per inch of alternate material
M
r
= r value per inch of
alternate
M
T
= minimum thickness required for alternate material
M
T
= standard thickness of the alternate material
S
k
= k value per inch of listed material
L
r
= r value per inch of
listed
L
T
= minimum thickness of
L
Note: An asterisk "*" indicates, it is a value taken from Table .
Using the k formula:
Minimum
thickness of
=
alternate
material (T
)
M
T
(inches)
=
M
T
(inches)
=
M
.312 (inches)=
Answer - The minimum required thickness of the Micore 160 is .372"
therefore round up to nearest standard thickness available which is
3/8" (.375")
8
material
material
material
listed
k-value (per Inch) of
alternate material (k
) x
M
k-value (per inch)
of listed material (k
)
L
k
x
M
*.47
*.35
x
*.47
.745
x
Using the r formula:
Minimum
thickness of
alternate
material
T
(inches)
M
T
(inches)
M
.312 (inches)=
Answer - The minimum required thickness of the Micore 160 is .372"
therefore round up to nearest standard thickness available which is
3/8" (.375")
Listed Material
Alternative Materials
Kaowool M Board
Micore 160™
U.S. Gypsum
Micore 300™
U.S. Gypsum
Durock™ Cement Board
U.S. Gypsum
Hardibacker™
Hardibacker 500™
Cultured Stone Hearth-
stone™
Wonderboard
Super Firetemp M
Johns-Manville
Super Firetemp L
Johns-Manville
Face brick
Common brick
Cement mortar
Ceramic tile
Marble
Specified min.
Table 1 - USA AND CANADA REQUIREMENTS
thickness
of listed
material (T
)
** If the hearth extension material(s) that is intended to be used is NOT
L
listed on Table 1, the material can still be used if the material(s) is non-
T
combustible. However, the manufacturer of the material must provide
L
either the listed k-value per inch or r-value per inch with listed thickness
so that the minimum thickness required for the hearth can be calculated
.50"
(per instructions here or as specified in the NFI Certification Manuals).
Note: Also see NFI (National Fireplace Institute) Certification Manuals show-
.50"
ing other acceptable calculation methods and acceptable alternate materials
which can be used.
r-value (per Inch)
=
of listed material
r-value (per inch)
of alternate material
r
=
L
r
M
=
*2.13
*2.86
.745
Listed Material
k (per inch)
r (per inch)
.47
2.13
r
K
L
L
** Approved Alternate Materials for Floor/Hearth Protection
Thermal Values
k (per inch)
r (per inch)
r
K
M
M
.47
2.13
.35
2.86
.46
2.17
1.92
.52
1.95
.51
2.30
.43
2.82
.35
3.23
.31
.61
1.64
.54
1.85
9.00
.111
5.00
.20
5.00
.20
12.5
.08
~11
~.09
Specified min.
x
thickness
of listed
material
x
T
L
x
.50"
x
.50"
Listed Min. Thickness
"
1/2
(.50")
T
L
Minimum Thickness
(rounded to nearest 1/8 inch)
Min. Thickness
T
M
.5" (1/2")
.37" (3/8")
.49" (1/2")
2.04" (1-1/8")
2.07" (1-1/8")
2.45" (2-1/2")
3" (3")
3.44" (3-1/2")
.65" (3/4")
.57" (5/8")
9.57" (9-5/8")
5.32" (5-3/8")
5.32" (5-3/8")
13.30" (13-3/8")
11.70" (11-3/4")
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