Heatilator • LM42 • Installers Manual • 4087-901 • Rev A • 04/14/16
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7
Facing, Mantels and Hearth Extensions
A. Facing and Finishing Instructions
WARNING! Risk of Fire!
DO NOT remove the installed
non-combustible board or cover it with combustible mate-
rial, such as:
• Drywall (gypsum board)
• Plywood
• Materials that do not meet the ASTM E 136 Non-com-
bustibility standard (below).
Removal of installed, non-combustible board and/or use
of materials not meeting the ASTM E 136 standard could
cause fire.
Wall sheathing materials 1/2 in. thick are specified in this
installation manual to properly align with the installed non-
combustible material.
When finishing the wall around the fireplace, it is critical
that wall sheathing be fastened properly.
It is acceptable to pre-drill holes and use self-tapped screws
in designated areas in the installed non-combustible board
which may be used to secure lathe (a backer for tile,
marble, etc.). Screws being installed through the installed
non-combustible board should be self-tapping type with a
maximum length of 1-1/4 inches. See Figure 7.1.
Non-Combustible Materials Specification
Material which will not ignite and burn. Such materials are
those consisting entirely of steel, iron, brick, tile, concrete,
slate, glass or plasters, or any combination thereof.
NOTICE: The finishing material not only includes the
decorative finish materials (marble, tile, slate, etc) but
also the thin set, lath and adhesive used to attach the
decorative finish material.
Finishing Materials
Finish and Sealing Joints
All joints between the finished wall sheathing and the ap
-
pliance must be sealed with non-combustible materials.
Sealants, such as caulk or mastic used to seal the gap
between the wall and the fireplace, should be rated at a
minimum continuous exposure to 300ºF.
Gypsum wallboard (drywall) joints adjacent to the fire
-
place non-combustible board on the appliance, require
special attention to minimize cracking.
Tape wall board joints around the fireplace non-
combustible board with fiberglass-mesh tape. It will
provide a more crack-resistant joint than paper tape. Fill,
smooth and finish wall joints with quick set joint compound
for first coat. It will provide a more crack-resistant joint
than air-drying lightweight compound.
In regards to the sheetrock mud, a smooth, even surface,
covering a wide area of the wall is desired for best results.
For best results, follow the tips below.
Figure 7.1 Designated Fastener Area
Section 7
Materials that are reported as passing
ASTM E 136, Stan-
dard Test Method for Behavior of Materials in a Verti-
cal Tube Furnace at 750 ºC.
6-1/4 in.
(159 mm)
42 in.
(1067 mm)
42 in.
(1067 mm)
3-3/4 in.
(95 mm)
18 in.
(475 mm)
3-3/4 in.
(95 mm)
2-3/4 in.
(70 mm)
1-1/4 in.
(32 mm)
12-3/8 in.
(314 mm)
7-3/4 in.
(197 mm)
7-3/4 in.
(197 mm)
27-3/4 in.
(705 mm)
62 in.
(1576 mm)
68 in.
(1727 mm)
Fastener Area
