Superior Fireplaces WRT3538WS Installation And Operation Instruction Manual page 9

HEARTH EXTENSION
A hearth extension projecting a minimum of 20" in front of and a
minimum of 12" beyond each side of fireplace opening is required
to protect combustible floor construction in front of fireplace. Fabri-
cate a hearth extension using a material which meets the following
specifications: a layer of noncombustible, inorganic material having a
thermal conductivity of k=0.84 BTU IN/FT, HR. F (or less) at 1" thick.
For example, if the material selected has a k factor of 0.25, such as
glass fiber, the following formula would apply:
0.25 x 1.0" = 0.30" thickness required
0.84
Thermal conductivity "k" of materials can be obtained from manufac-
turer or supplier of noncombustible material. If hearth extension is
to be covered, use noncombustible material such as tile, slate, brick,
concrete, metal, glass, marble, stone, etc. Provide a means to prevent
hearth extension from shifting and seal gap between fireplace frame
and hearth extension with a noncombustible material (see Figure 8).
WARNING: Hearth extension is to be installed only
as shown in Figure 8.
Fireplace Front
Ember Protector
Fireplace Front Raised
Hearth
Ember Protector
Fireplace Front Elevated
Ember Protector
Figure 8 - Hearth Extension
900855-00_B
FIREPLACE INSTALLATION Continued
Seal Gap
Hearth
Extension
Seal Gap
SuperiorFireplaces.us.com
MANTELS
A mantel may be installed if desired (see Figure 9). Woodwork such
as wood trims, mantels or any other combustible material projecting
from front face must not be placed within 12" of the fireplace (NFPA
211, Section - Clearance from Combustible Material).
Mantels or any other combustible material also may come up to side
edge of black metal face of fireplace as long as projections from front
face fall within limit shown in Figure 9.
(305 mm)
Max.
12"
(305 mm)
Min.
Combustible
Mantel
* A 1-1/2" Projection Is Permitted
Between The Face Top And Mantle
Combustible Materials
Allowed in Shaded Area
4-17/32"
(115 mm)
12" (305 mm)
Minimum Distance
to Protected Side Wall
Figure 9 - Mantel Clearances to Combustible Materials
Finished Wall
Header
12"
Spacer
*
Noncombustible
Wall Covering
Fireplace Opening
1/2"
(13 mm)
30˚
9