Marco BM36HCD - Hearth Extension Requirements; Hearth Extension Dimensions and Protection

FIEPLACE FLUSH itrITH WALL
HEARTH EXEUSICN'
FIGURE 24
HEARTH EXTENSION:
The hearth extensior~ Inus! bc madr from a non-combus-
If &re is a combustible floor constrdc!ion in front of *e
tiblchorganicmaterial wi:ha thermal condnctivity, K, 0f.S-l
fireplace, you are required to protecf it with a hearth
or less. The themal conductivity, K, or thermal resistance,
extension.
P.e hear& extension, as sh~wz in Figure 25,
R ofmaterials cm~sually be obtsined from the rr.mufactu:er.
must be a r,lir;irr,zm oi 16" de~p by 46" wide, an6 cxtend
The factors are related by the forrn~~la K - 118.
!h+ckness
E minimum of X" beyond each .ide oi the fire?lace
repired for various ccmnlon mn!e;iii!s and the& !zc!o;s are
opening. iho'*n in Figwe 25.
COMMON MATERIALS AND THEIR FACTORS ?
*Units of K are BTUIHR FT'F
TYPE OF INSULATION 1 K. 1 HIN. THICKNESS RECI'D
U.S. Gypurn Ccrp.
1 4 1 .52"
I
Micsre C'I230 I
I I_!
I ! 1
I LydnIl, Inc. I
1 LTfiEfiXi iw:
I
1 .% ( .76"
r
I Standard 041
Durzrock I
i
1 ?.92
Cement Board
I
I I
2.29"
I
I I
! lL-----4 FIGURE 26 /
f i r e - p a r t s . c o m