Heatilator ST42A Installation Manual page 29

1. Fireplace Installed Flush on the Floor and
Hearth Extension Raised to Bottom of Firebox
Opening
1RQFRPEXVWLEOH ÀRRULQJ D PLQLPXP RI  LQ  PP
LQ IURQW RI DQG  LQ  PP WR HDFK VLGH RI WKH IXHO
RSHQLQJ LV UHTXLUHG
7KH KHDUWK IUDPLQJ PXVW EH FRQVWUXFWHG RI QRQFRP-
EXVWLEOH PDWHULDOV VXFK DV PHWDO IUDPLQJ RU HTXLYDOHQW
PDWHULDO DQG SODFHG RQ +; V  +; V  RU HTXLYDOHQW
PDWHULDO 6HH )LJXUHV  DQG 
When creating the platform, allow for the thickness
RI WKH QRQFRPEXVWLEOH ¿QLVKLQJ PDWHULDOV.
6HDO JDSV EHWZHHQ WKH KHDUWK H[WHQVLRQ DQG WKH IURQW
RI WKH ¿UHSODFH ZLWK D EHDG RI QRQFRPEXVWLEOH VHDODQW
RU JURXW
Note: Maximum height from floor under fireplace
to top of finished hearth extension is 5 7/8 in.
Bottom of fireplace opening
Continuous,
non-combustible sealant
Tile, stone or other
non-combustible material
1/2 in. Micore
or equivalent
insulation
Floor constructed of wood or
other combustible material
1RWH )RU LQVWDOODWLRQV
ZLWK YLQ\O ÀRRULQJ VSHFLDO
FOHDUDQFH UHFRPPHQGD-
tions apply.
Figure 7.4 Hearth Extension Construction
Vinyl Flooring
9LQ\O )ORRULQJ LV VHQVLWLYH WR KHDW $  LQFK PLQLPXP
GHSWK KHDUWK H[WHQVLRQ LV UHFRPPHQGHG ZKHQ XVLQJ YL-
Q\O ÀRRULQJ XS WR WKH ZDOO 6HH )LJXUH 
1RWLFH &OHDUDQFHV WKDW GR QRW PHHW WKH PLQLPXP
JXLGHOLQHV FRXOG UHVXOW LQ GDPDJH RU EXFNOLQJ WR WKH YL-
Q\O ÀRRULQJ DQG LV GRQH DW WKH LQVWDOOHU¶V ULVN
+HDUWK DQG +RPH 7HFKQRORJLHV GRHV QRW UHFRPPHQG
DGKHVLYH EDVHG YLQ\O ÀRRULQJ GXH WR WKHUPDO H[SDQVLRQ
)ORDWLQJVW\OH ÀRRULQJ FDQ EH XVHG EXW ZLOO UHDFK WHP-
SHUDWXUHV XS WR ƒ) LQ D URRP ZLWK DPELHQW WHPSHUD-
WXUHV RI ƒ) &RQVXOW ÀRRULQJ VSHFL¿FDWLRQV WR HQVXUH
FRPSDWLELOLW\
Protective
Metal Hearth
Strip
2 in. (51 mm)
required
Heatilator • ST42A Installation Manual • 4012-051 • Rev O • 02/22
Note: The bottom of the fireplace
opening is 5 7/8 in. (149 mm)
above the bottom of the
fireplace. Finished hearth must
NOT extend above this level.
Noncombustible
Finishing Material
20 in. Min.
Hearth Extension
Noncombustible
Framing Material
1/2 in. Micore
or equivalent
insulation
Figure 7.5 Raised Platform Hearth Extension Detail
Noncombustible
Framing Material
Figure 7.6 Raised Platform Hearth Extension-Framing
Non-combustible
Finishing Materials
Figure 7.7 Raised Platform Hearth Extension-Finishing
Floor
Protective Metal
Hearth Strips
HX4 or
equivalent