Fireplace Installation
Continued
Hearth Extension
A hearth extension projecting a minimum of 16" in front of and a minimum of 8" beyond each side of fireplace opening is required to protect combustible floor construction in front of fireplace. Fabricate a hearth extension using a material which meets the following specifications: a layer of noncombustible, inorganic material having a thermal conductiv- ity of K=0.84 BTU IN/FT, HR. F (or less) at 1" thick. For example, if material selected has a K factor of 0.25, such as glass fiber, the following formula would apply:
0.25x 1.0" = 0.30" thickness required
Thermal conductivity "K" of materials can be obtained from manufacturer or supplier of noncombustible material. If hearth extension is to be covered, use noncombustible mate- rial such as tile, slate, brick, concrete, metal, glass, marble, stone, etc. Provide a means to prevent hearth extension from shifting and seal gap between fireplace frame and hearth extension with a noncombustible material (see Figure 3).
WARNING: Hearth extension
is to be installed only as shown
in Figure 3.
Seal Gap
Fireplace Front
Ember Protector
NO |
|
Do Not Block Louver | Hearth |
| |
| Extension |
Fireplace Front | Seal Gap |
Elevated |
|
Ember Protector
Hearth Extension, Circulating Modes
Seal Gap
Fireplace Front
Ember Protector
Fireplace Front |
|
Raised Hearth |
|
Ember Protector | Hearth |
| |
| Extension |
Fireplace Front | Seal Gap |
Elevated |
|
Ember Protector |
|
