Common Materials and Factors

SR/SC Series "A" Woodburning Fireplace

MATERIAL	K*	R	MINIMUM
			THICKNESS

EH2416	0.50 in.**
(CFM Corporation) 0.458 1.09	0.50 in.**

Common Brick 5.0 0.10	5.46 in.**

R Value is for ¹⁄₂ inch.

*Units of K = BTU/SQ FT/HR/ßF/IN

**Thickness of Listed Material

FP533ADD

Fig. 24 Hearth extension material factors.

WARNING: HEARTH EXTENSION MUST BE INSTALLED IN ACCORDANCE WITH FIGURE 23 AND MUST NOT COVER THE BOTTOM FRONT OPENING OF THE CIRCULATING MODEL.

Alternate noncombustible materials may be used providing the (total) thermal resistance (Rt value) of the alternate material employed is greater than or equal to R = 1.09. Thermal resistance (R) or thermal conductivity (K), may be obtained from manufacturer of the material. Factors are related by the formula K = 1/R.

T = given thickness

R = thermal resistance for a given thickness (T) K = thermal conductivity

Noncombustible material with a lower R value may be used, provided thickness of material is sufficiently greater to maintain an equivalent (total) thermal resistance (Rt).

Example of Determining Hearth Extension Equivalents

To determine the thickness required for any new material:

NEW	K of new material (per inch)	thickness
required =		x of listed
required =		x of listed
thickness	K of listed material (per inch)	material

Example for Common Brick

T (new) = 5.0/0.458 x 0/50 in. = 5.46 in. (new required thickness).

Side View

Wall Covering

Noncombustible

2 x 4 Header

Decorative

(Do not notch

Facing

at standoffs)

Seal all cracks

between fireplace

surround and wall

materials with

noncombustible

material

Noncombustible

Decorative

Covering

Seal crack between

Hearth Extension

fireplace and hearth

extension with

Insulation

noncombustible

material

Safety Strips

Must be overlapped 1/2"

FP550

minimum

Fig. 25 Sealing gaps.

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