BENEATH HEARTH EXTENSION
Unless raised 4” above the base of the
hearth, the Onyx AP must use a 1/2” Durock
ciment board with a metal sheet (0.025”) or a
3/4” Micore 160 board beneath the hearth
extension (non-combustible material).
If the fireplace is raised 4" or more, the area
in front of the fireplace just needs to be
covered with a non-combustible material,
such as metal, brick, stone or slate. There is
no minimum thickness required for this non-
combustible hearth extension. The 5" wide
spark guard must be installed underneath
either the hearth extension or the protective
board.
NOTE: If the Onyx AP is installed on a con-
crete floor, the protective board and spark
guards are not required.
HEARTH EXTENSION
The area immediately in front of the fireplace
must be protected by a non-combustible
material such as brick, tile, stone, or slate.
The protection must extend at least 16" in front (See figure
14) of the fireplace door opening. There is no minimum thick-
ness required for the hearth extension.
MANTEL
A masonry or other non-combustible mantel may be placed
directly above the top louvers. If a wood or other combustible
mantel is desired, it must be at least 14 inches above the top
of door (See Figure 14 & 15).
No combustible materials
behind sheeting below
this line
5 1/2"
max.
Header
12" max.
12"
max.
Silicone
seal
Sheeting
Header
Silicone
seal
2" min.
Adjustment slot
Sheeting
Silicone
seal
14" min. Facing
Expanded metal
With FDKO facing kit
Figure 15 : Mantel installation
Non-
combustible
material
Metal
Figure 14: Clearances to combustibles and hearth requirements
39”
12
”
ma
x
23”
28”
42”
42”
16”
4”
20 min”
14" min. from top of door (40" min.
from the base of the fireplace)
5" max out from face
6 1/4" min. to com-
bustible surround
8 1/2" min. to side wall
Non-combustible material
(permanently attached)
Non-combustible
material
Protective board
1/2” Durock with
metal sheet or 3/4”
Micore board
z-shaped spark guard
5" wide spark
guard
0” clearance to
stand off
RAISED INSTALLATION
ONYX AP Owner's Manual
RSF Woodburning Fireplaces
16
