Fireplace Installation

Continued

Hearth Extension

A hearth extension projecting a minimum of 20" in front of and a minimum of 12" 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 conductivity 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 material 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

 

Hearth Extension, Noncirculating Models

Figure 3 - Hearth Extension

115386-01D

www.fmiproducts.com

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