17. 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 front of the fireplace with a bead of noncombustible sealant.
Figure 17 - Factory Built Hearth Extension
Field constructed hearth extensions should be constructed in accordance with the instructions in Figure 18. The field constructed hearth extension must be constructed from ½” MICORE CV230, or a material with an equivalent insulation value.
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 burning or hot particles from inadvertently falling directly on combustible surfaces in the event the building should settle and disturb the original construction.
20 | 26022 Rev i | 08/04 |