20
31068 Rev E
08/04
MHST36D INSTALLATION INSTRUCTIONS
Figure 17 - Factory Built Hearth Extension
Figure 18 - Field Constructed Hearth Extension
WARNING!
Hearth extensions are to be installed only as illustrated to prevent high temperatures
from occurring on concealed combustible materials. Hearth sealing strips prevent burn-
ing or hot particles from inadvertently falling directly on combustible surfaces in the event
the building should settle and disturb the original construction.
14. 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 17 and 18. 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 fireplace with a bead of noncombustible
sealant.
Field constructed hearth extensions should be constructed in accordance with the instructions in Figure 18. The field
constructed hearth extension must be constructed from 1/2 in. MICORE CV230 or a material with an equivalent
insulation value.