LG Electronics LS43ST Methods of Determini

Hearth Extension Dimensions

A

20"

B

39-3/8"

C

12"

D

63-3/8"

C

B

C

Note: To convert inches to millimeters

A

divide by 0.03937

D

Figure 48

Methods of Determining Hearth Extension and Wall Shield

Answer - The minimum required thickness of the Micore 160 is .417”,

Equivalents - To determine the thickness required for the alternate

therefore round up to nearest standard thickness available which is 1/2”.

material when either the “k” value or “r” value is known, use either the

k formula or r formula.

Listed Material

Example: If Micore 160 is to be used for the hearth extension fireplace,

k (per inch)

r (per inch)

Listed Min.Thickness

Listed Material

.84

1.19

1"

how thick must this material be?

KL

rL

TL

kM = k value per inch of alternate material

** Approved Alternate Materials for Floor/Hearth Protection

rM = r value per inch of alternate material

AlternativeMaterials

Thermal Values

MinimumThickness

TM =

minimum thickness required for alternate material

(rounded to nearest 1/8 inch)

TS =

standard thickness of the alternate material

k (per inch)

r (per inch)

Min. Thickness

KM

rM

TM

kL = k value per inch of listed material

Kaowool M Board

.47

2.13

.56" (1/2")

rL = r value per inch of listed material

Micore 160™

.35

2.86

.42" (3/8")

TL = minimum thickness of listed material

U.S. Gypsum

Note: An asterix “*” indicates, it is a value taken from Table 1.

Micore 300™

.46

2.17

.55" (1/2")

U.S. Gypsum

Using the k formula:

Durock™ Cement Board

1.92

.52

2.29" (2-1/4")

Minimum

k-value (per Inch) of

Specified min.

U.S. Gypsum

Hardibacker™

1.95

.513

2.32" (2-3/8")

thickness of

=

alternate material (kM) x

thickness

Hardibacker 500™

2.30

.435

2.74" (2-3/4")

alternate

k-value (per inch)

of listed

material (TM)

of listed material (kM)

material (TL)

Cultered Stone Hearth-

2.82

.355

3.36" (3-3/8")

stone™

TM (inches)

=

kM

x

TL

Wonderboard

3.23

.31

3.85" (3-7/8")

*.84

Super Firetemp M

.61

1.64

.73" (3/4")

Johns-Manville

TM (inches)

=

*.35

x

1"

Super Firetemp L

.54

1.85

.64" (5/8")

*.84

Johns-Manville

.416

(inches) =

.416

x

1"

Face brick

9.00

.111

10.71" (10-3/4")

Common brick

5.00

.20

5.95" (6")

Answer - The minimum required thickness of the Micore 160 is .417”,

Cement mortar

5.00

.20

5.95" (6")

therefore round up to nearest standard thickness available which is 1/2”.

Ceramic tile

12.5

.08

14.88" (14-7/8")

Using the r formula:

Marble

~11

~.09

13.10" (13-1/8")

Table 1

Minimum

r-value (per Inch)

Specified min.

thickness of

=

of listed material

x

thickness

** If the hearth extension material(s) that is intended to be used is NOT listed

alternate

r-value (per inch)

of listed

on Table 1, the material can still be used if the material(s) is noncombustible.

material

of alternate material

material

However, the manufacturer of the material must provide either the listed k-

TM (inches)

=

rL

x

TL

value per inch or r-value per inch with listed thickness so that the minimum

thickness required for the hearth can be calculated (per instructions on this

rM

Page and/or as specified in the NFI Certification manuals).

TM (inches)

=

*1.19

x

1"

Note: Also see NFI (National Fireplace Institute) Certification Manuals showing

*2.86

other acceptable calculation methods and acceptable alternate materials

.416

(inches) =

.416

x

1"

which can be used.

18

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.