Majestic fireplaces SC36A Homeowner's Installation And Operating Manual page 17

COMMON MATERIALS AND FACTORS
MATERIAL
EH2416
(CFM Corporation) 0.458
Common Brick 5.0
R Value is for
* Units of K = BTU/SQ FT/HR/ßF/IN
** Thickness of Listed Material
Fig. 24 Hearth extension material factors.
WARNING: HEARTH EXTENSION MUST BE
INSTALLED IN ACCORDANCE WITH FIGURE 23
AND MUST NOT COVER THE BOTTOM FRONT
OPENING OF THE CIRCULATING MODEL.
Alternate noncombustible materials may be used
providing the (total) thermal resistance (Rt value) of
the alternate material employed is greater than or
equal to R = 1.09. Thermal resistance (R) or thermal
conductivity (K), may be obtained from manufacturer
of the material. Factors are related by the formula K =
1/R.
T = given thickness
R = thermal resistance for a given thickness (T)
K = thermal conductivity
Noncombustible material with a lower R value may be
used, provided thickness of material is sufficiently
greater to maintain an equivalent (total) thermal
resistance (Rt).
Example of Determining Hearth Extension
Equivalents
To determine the thickness required for any new
material:
NEW
K of new material (per inch)
=
required
thickness
K of listed material (per inch)
Example for Common Brick
T (new) = 5.0/0.458 x 0/50 in. = 5.46 in. (new required
thickness).
7412948
MINIMUM
K* R
THICKNESS
1.09 0.50 in.**
0.10 5.46 in.**
inch.
FP533ADD
thickness
x
of listed
material
SR/SC Series "A" Woodburning Fireplace
Side View
Wall Covering
Noncombustible
Decorative
Facing
Seal all cracks
between fireplace
surround and wall
materials with
noncombustible
material
Noncombustible
Decorative
Covering
Hearth Extension
Insulation
FP550
Fig. 25 Sealing gaps.
2 x 4 Header
(Do not notch
at standoffs)
Seal crack between
fireplace and hearth
extension with
noncombustible
material
Safety Strips
Must be overlapped 1/2"
minimum
17