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The spark guard provided (L) must be installed 2½" under the fireplace bottom
standoff and 2½" under the hearth extension, centered on the fireplace opening. It is
dimensioned so that it will also cover the entire floor area under the metal front step
of the fireplace (see Figure 6). This guard prevents sparks from lodging in this area
and starting a fire.
If you are installing the fireplace on a raised combustible platform, you will need a
second spark guard (not provided) with the same dimensions as the one we have
provided. One spark guard will be installed at the floor, below the hearth extension
and the raised platform. The second spark guard will be installed at the base of the
fireplace itself. Both spark guards must be centered on the fireplace opening.
Thermal protection of a minimum R-Value of 2.20
2.
Adequate thermal protection must be provided for the combustible floor structure of
the hearth extension. The thermal protection must have the same minimum
dimensions as the hearth extension (see Table 1 (G-H)) and it must be installed
under the non-combustible flooring and above the spark guard.
See Table 7 for various possibilities. If you want to use alternative materials, you
simply need to add the R-Values of each material considered for the hearth
extension. The R-Values are linked to the thickness of the material, if the material
considered is twice the thickness in our table; just multiply by two the R-Value. For
example:
•
1" Micore 300 and 4" of Sandstone: (2 x 1.03) + (4 x 0.05) = 2.26 R-Value
•
4" Durock and 1 ½" of Limestone: (8 x 0.26) + (1.5 x 0.108) = 2.24 R-Value
•
4 ½" HardieBacker and ¼" ceramic tile: (9 x 0.26) + 0.02 = 2.36 R-Value
A raised hearth constructed of non-combustible cement board and metal studs will
provide adequate thermal protection.
Table 7 Thermal Protection Alternatives for the Hearth Extension
Material
Nominal
Thickness
R-Value for nominal
thickness
Cement board: Durock or HardieBacker
3
½"
0.26
Cement board: Wonderboard
4
½"
0.15
USG Micore 160
3
½"
1.27
USG Micore 300
3
½"
1.03
Common Brick
5
2
3
/
8
"
0.475
Ceramic Tile
¼"
0.02
Granite
6
1"
0.038
Limestone
6
1"
0.108
Marble
6
1"
0.049
Sandstone
6
1"
0.05
Quartzite
6
1"
0.027
3
From Manufacturers technical data
4
Hearth & Home Magazine, July 2008, page 70.
5
From the ColoradoENERGY.org
6
From the Marble Institute of America
Summary of Contents for RUMFORD 1500
Page 1: ...RUMFORD 1500...
Page 8: ...GENERAL SPECIFICATIONS 8 Figure 2 Fireplace Clearances...
Page 13: ...INSTALLATION 13 Figure 4 General Installation...
Page 43: ...30 Year Limited Warranty 43...
Page 44: ...RR1500B 2016 07...
