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calculating minimum Thickness if
multiple materials are used
At times it is important to know what
combination of materials are acceptable for use
as floor protection. The "R values" are used to
determine acceptable combinations of materials
because "R values" are additive where r and k
values are not.
"r value" = 1/k = "r" x thickness of material
used
Example: Given that the required "R value"
for a suitable floor protector used must be
equal to or greater than:
"R" =
x T
= 1.19 x 1" = 1.19."
r
L
L
If it is desired to elevate a marble hearth
extension to a level of 5" or more above
the floor surface. What combination of
noncombustible materials can be used to
accomplish this?
If common brick is used so that the 3-1/2"
dimension is the height, "R" for the common
brick becomes:
brick
"R"
= r
x T
= 0.20 x 3-1/2" = .70
M
M
S
Using 1/2" of mortar to set the brick, "R" for
the mortar is calculated as follows:
mortar
"R"
= r
x T
= 0.20 x 1/2" = .10
M
M
S
Next, a 3/4" marble slab set in 1/2" mortar cov-
ers the brick, "R" for the marble and mortar
becomes:
marble
"R"
= r
x T
= 0.05 x 3/4" = .038
M
M
S
mortar
"R"
= r
x T
= 0.20 x 1/2" = .10
M
M
S
The sum of all "R values" is: .70 + .10 +. 038
+ .10 = .938
This would NOT be an acceptable combination
of material for the hearth extension since the
total calculated "R value" of the materials used
is under the required "R value" of 1.19. An
additional layer of insulating materials must
be used.
ee NFI Certification Manuals for
Note: Also s
expanded explanation on calculating "R val-
ues" when multiple materials are used.
0
warnInG
The crack between the fireplace
and the hearth extension must be
sealed with a noncombustible
material.
warnInG
when installing hearth extension
in front of a non-circulating fire-
place model, the fireplace must be
raised if height of hearth extension
exceeds 5-3/4" above the bottom of
fireplace (Figure 47).
when installing the hearth exten-
sion be careful not to block the
heat-circulating air inlet grill on
circulating models.
*
5 ¹⁄₈" (130 mm)
If "c" style door
Is used.
*
5 ⁵⁄₈"
(143 mm)
max.
maximum Thickness of hearth extension
when fireplace is on the floor.
Figure 47
fInIsh To your TasTe
There are a wide variety of "finished looks"
for your Fireplace from formal wall decor with
elaborate mantels to rustic wood paneling or
warm brick facings.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Only noncombustible materials like marble,
stone, tile, brick, etc. may overlap the black
front facing, but be careful not to interfere
with the operation of the glass doors. Seal
all joints between the black facing and wall
surrounds to prevent cold air intrusion. Use
noncombustible caulking material only to seal
the black metal facing to the surround material
on the finished wall.
Combustibles may also project beyond the
sides of the fireplace opening as long as they
are kept within the shaded areas, as illustrated
in Figure 48.
combustible
materials allowed
in shaded area
4 ⁵⁄₈"
(118 mm)
1" (5 mm)
30˚
11 ³⁄₈"
(89 mm)
8" (03 mm)
minimum distance
to Protected side wall
18"
minimum distance
(457 mm)
to unprotected side wall
model csT-38
Figure 48
accessory ParTs and comPonenTs
lIsT for model csT38mh
The accessory parts and components shown on
Pages 21 and 22 are to be used only with your
CST-38MH fireplace system. Separate installa-
tion instructions are packaged with all combus-
tion air kits and chimney terminations.
If you encounter any problems or have ques-
tions concerning the installation or application
of this system, please contact your distributor.
For the name of your nearest distributor, please
call 1-800-953-6669.
lhP
1110 west Taft avenue
orange, ca 9865
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