Hearth Extension - Heatilator CONSTITUTION Installation & Operating Instructions Manual

14.
Installing the Roof Flashing
If a roof flashing is to be used, install the roof flashing
appropriate to the roof pitch and install a round termination
cap following the instructions shipped with the cap.
For chase installations you can use a round termination
cap (TR344), a round telescoping termination cap (TR342)
or a square termination cap (ST375). A chase installation
must use a chase top. Chase tops are available from your
dealer. See page 19 for building a chase.
15.
Completion of the Enclosure
Complete the fireplace enclosure, allowing space for
outside air ducts. Electrical wiring should not come in
contact with the fireplace. A minimum clearance of 1"
must be maintained between the fireplace sides and
back and the enclosure. See pages 9-10 for framing
details.
16.

Hearth Extension

A hearth extension must be installed with all fireplaces to
protect the combustible floor in front of the fireplace from
both radiant heat and sparks.
The construction of, and materials used for a hearth
extension are shown in Figures 17A and 17B. A hearth
extension of this construction may be covered with any
noncombustible decorative material and may have a
maximum thickness as per the illustration. Seal gaps
between the hearth extension and the front of the fireplace
with a bead of noncombustible sealant.
1. Hearth Extension & Floor Protection flush on the
floor.
Combustible flooring 20" in front of and 8" to either side of the fuel
opening; must be insulated with non-combustible floor protection with a minimum thickness of 1" ("k" value = 0.43). Use Alternate
Material Worksheet on page 18 to determine the "k" value of the alternative material..
2. Fireplace is flush on the floor and Hearth Extension is raised to the bottom of the fascia:
Raised hearth must be constructed of non-combustible materials such as cement block or equivalent material Decorative
combustible flooring on the raised hearth must be 20" (508mm) in front of and 8" (203mm) to either side of the fuel opening must be
insulated with non-combustible floor protection with a minimum thickness of 1-1/2" (38mm) and ("k" value = 0.43).
3. Fireplace is recessed in the floor to the bottom of the fascia:
Combustible flooring 30" (762mm) in front of and 8" (203mm) to either side of the fuel opening; must be insulated with
non-combustible floor protection with a minimum thickness of 1" (25mm) and ("k" value = 0.43).
4-03
NONCOMBUSTIBLE
DECORATIVE MATERIAL
1" (51mm)
(2) HX4 MICORE FACTORY
BUILT HEARTH EXTENSION
(Each HX4 = 1/2" (13mm) thick)
Figure 17B - Factory Built Hearth Extension
CLEARANCES!
A minimum 1" air clearance must be maintained at
the back and sides of the fireplace assembly.
Chimney sections at any level require a 2" minimum
air space clearance between the framing and
chimney section.
NOTE: Use only a noncombustible material to finish the
face of the fireplace below the level of the front standoffs.
A noncombustible material such as USG MICORE CV230
Mineral Fiber Board, or USG DUROCK Cement Board is
recommended for this purpose.
20"
Figure 17A - Field Construction Hearth Extensions
GAP (SEAL WITH NONCOMBUSTIBLE SEALANT)
UP TO BOTTOM OF FASCIA
HEARTH METAL STRIPS
17
Constitution
EPA Certified Fireplace
8" from each side of
fuel loading door
41"
6" (152mm)
480-1091