Hearth and Home Technologies BIR42 Finishing, Hearth Extension, = 1/k x inches of thickness

12 Finishing

A. Non-Combustible Materials

•Materials which will not ignite and burn, composed of any combination of the following:

-	Steel	-	Iron
-	Brick	-	Tile
-	Concrete	-	Slate
-	Glass	-	Plasters

•Materials reported as passing ASTM E 136, Standard

Test Method for Behavior of Metals, in a Vertical Tube Furnace at 750° C

B. Combustible Materials

•Materials made of or surfaced with any of the following materials:

-	Wood	-	Compressed paper
-	Plant fibers	-	Plastic

•Any material that can ignite and burn; flame proofed or not, plastered or un-plastered

•You MUST use a hearth extension with this fireplace.

•This fireplace has been tested and approved for use with a hearth extension insulated to a minimum R value of 2.32.

•The hearth extension material MUST be covered with tile, stone or other non-combustible material.

•Manufactured hearth materials will usually have a published R value (resistance to heat) or k value (conductivity of heat). Refer to the formula in Table 12.1 to convert a k value to an R value,

•Refer to Table 12.2 for hearth extension insulation alternatives.

C. Hearth Extension

WARNING! Risk of fire! High temperatures, sparks, em- bers or other burning material falling from the fireplace may ignite flooring or concealed combustible surfaces.

•Metal hearth strips MUST be installed (Section 7.C.).

•Hearth extensions MUST be installed exactly as specified.

Table 12.1

R = 1/k x inches of thickness

12in.

(305 mm)

42 in.

(1067 mm)

66 in.

(1676 mm)

(R value of hearth must be equal to or greater than 2.32)

12in.

(305 mm)

Raised Platform

20 in. (508 mm) Minimum

Flush Hearth

30 in. (762 mm) Minimum

Table 12.2

Figure 12.1 Hearth Extension Dimensions

Hearth Extension Insulation Alternatives-Total minimum R Value must equal 2.32

	k per inch	R per inch
Material	thick	thick	Minimum thickness required
Hearth & Home HX3, HX4 (Micore 300™)	0.49	2.06	1 in. (25.4 mm)
USG Micore 160™	0.39	2.54	1 in.(25.4 mm)
USG Durock™ Cement Board	1.92	0.52	4 in. (101.6 mm)
Cement Mortar	5.0	0.20	10 in. (254 mm)
Common Brick	5.0	0.20	10 in. (254 mm)
Ceramic Tile	12.50	0.08	25-3/4 in. (654 mm)
Armstrong™ Privacy Guard Plus	0.46	2.18	1 in. (25.4 mm)
Marble	14.3 to 20.0	0.07 to 0.05	29-1/2 to 41 in. (749.3 to 1041.4 mm)

Heatilator • Birmingham BIR42 • 4059-308 F • 11/08 41