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COMMON MATERIALS AND FACTORS
MATERIAL
EH2416
(MHSC)
Common Brick
R Value is for 1/2 inch.
* Units of K = BTU/SQ FT/HR/˚F/IN
** Thickness of Listed Material
Fig. 25 Hearth extension material factors.
WARNINg: hEARTh EXTENSION MUST BE IN-
FP533ADD
Addendum
STALLED IN ACCORDANCE WITh FIgURE 25 AND
6/1/99 djt
MUST NOT COVER ThE BOTTOM FRONT OPENINg
8/4/99 changed .2 to .1
OF ThE CIRCULATINg MODEL.
one inch to 1/2 inch djt
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 Equiva-
lents
To determine the thickness required for any new mate-
rial:
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).
20006811
MINIMUM
K*
R
THICKNESS
0.458
1.09
0.50 in.**
5.0
0.10
5.46 in.**
FP533ADD
Thickness
X of listed
material
ODSR Series "A" Outdoor Woodburning Fireplace
Side View
Wall Covering
Noncombus-
tible Decorative
Facing
Seal all cracks
between fireplace sur-
round and wall materi-
als with noncombus-
tible material
Noncombustible
Decorative Cov-
ering
Hearth Extension
Insulation
FP550
Fig. 26 Sealing gaps.
2 x 4 Header
(Do not notch
at standoffs)
Seal crack between
fireplace and hearth
extension with noncom-
bustible material
Safety Strips
Must be overlapped 1/2"
minimum
FP550
BR/BC - SEALING
DETAILS
9/29/97
17
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