Fireplace Installed Flush On The Floor And Hearth Extension Raised To Bottom Of Firebox Opening - Heatilator MHST36D Installation Manual

1. Fireplace Installed Flush on the Floor and
Hearth Extension Raised to Bottom of Firebox
Opening
Non-combustible flooring a minimum of 16 in. (406 mm)
in front of and 8 in. (203 mm) to each side of the fuel
opening is required.
The hearth framing must be constructed of non-com-
bustible materials (such as metal framing or equivalent
material) and placed on HX3(s), HX4(s), or equivalent
material. See Figures 7.4 and 7.5.
When creating the platform, allow for the thickness
of the non-combustible finishing materials.
Seal gaps between the hearth extension and the front
of the fireplace with a bead of non-combustible sealant
or grout.
Note: Maximum height from floor under fireplace
to top of finished hearth extension is 6 in.
Bottom of fireplace opening
Continuous,
non-combustible sealant
Tile, stone or other
non-combustible material
1/2 in. Micore
or equivalent
insulation
Floor constructed of wood or
other combustible material
Figure 7.4 Hearth Extension Construction
Protective
Metal Hearth
Strip
2 in. (51 mm)
required
Heatilator • MHST36D Installation Manual • 4012-086 • Rev D • 03/17
Note: The bottom of the front
face is 6 in. (152 mm) above the
bottom of the fireplace. Finished
hearth must NOT extend above
this level.
Noncombustible
Finishing Material
Hearth Extension
Noncombustible
Framing Material
1/2 in. Micore
or equivalent
insulation
Figure 7.5 Raised Platform Hearth Extension Detail
Noncombustible
Framing Material
Figure 7.6 Raised Platform Hearth Extension-Framing
Non-combustible
Finishing Materials
Figure 7.7 Raised Platform Hearth Extension-Finishing
16 in. Min.
Floor
Protective Metal
Hearth Strips
HX4 or
equivalent
25