Page 480 - 2018_IRC

CHIMNEYS AND FIREPLACES

R1003.17 Masonry chimney cleanout openings. Cleanout R1003.19 Chimney fireblocking. Spaces between chimneys
openings shall be provided within 6 inches (152 mm) of the and floors and ceilings through which chimneys pass shall be
base of each flue within every masonry chimney. The upper fireblocked with noncombustible material securely fastened
edge of the cleanout shall be located not less than 6 inches (152 in place. The fireblocking of spaces between chimneys and
mm) below the lowest chimney inlet opening. The height of wood joists, beams or headers shall be self-supporting or be
the opening shall be not less than 6 inches (152 mm). The clea- placed on strips of metal or metal lath laid across the spaces
nout shall be provided with a noncombustible cover. between combustible material and the chimney.
Exception: Chimney flues serving masonry fireplaces R1003.20 Chimney crickets. Chimneys shall be provided
where cleaning is possible through the fireplace opening. with crickets where the dimension parallel to the ridgeline is
R1003.18 Chimney clearances. Any portion of a masonry chim- greater than 30 inches (762 mm) and does not intersect the
ney located in the interior of the building or within the exterior ridgeline. The intersection of the cricket and the chimney
wall of the building shall have a minimum airspace clearance to shall be flashed and counterflashed in the same manner as
combustibles of 2 inches (51 mm). Chimneys located entirely out- normal roof-chimney intersections. Crickets shall be con-
side the exterior walls of the building, including chimneys that pass structed in compliance with Figure R1003.20 and Table
through the soffit or cornice, shall have a minimum airspace clear- R1003.20.
ance of 1 inch (25 mm). The airspace shall not be filled, except to TABLE R1003.20
provide fire blocking in accordance with Section R1003.19. CRICKET DIMENSIONS
ROOF SLOPE H
Exceptions:
12:12 1 / of W
1. Masonry chimneys equipped with a chimney lining 2
system listed and labeled for use in chimneys in 8:12 1 / of W
3
contact with combustibles in accordance with UL 6:12 1 / of W
4
1777 and installed in accordance with the manufac- 4:12 1 / of W
turer’s instructions are permitted to have combusti- 1 6
ble material in contact with their exterior surfaces. 3:12 / of W
8
2. Where masonry chimneys are constructed as part of
masonry or concrete walls, combustible materials SECTION R1004
shall not be in contact with the masonry or concrete FACTORY-BUILT FIREPLACES
wall less than 12 inches (305 mm) from the inside R1004.1 General. Factory-built fireplaces shall be listed and
surface of the nearest flue lining.
labeled and shall be installed in accordance with the condi-
3. Exposed combustible trim and the edges of sheath- tions of the listing. Factory-built fireplaces shall be tested in
ing materials, such as wood siding and flooring, accordance with UL 127.
shall be permitted to abut the masonry chimney side
walls, in accordance with Figure R1003.18, pro- R1004.2 Hearth extensions. Hearth extensions of approved
factory-built fireplaces shall be installed in accordance with
vided such combustible trim or sheathing is not less the listing of the fireplace. The hearth extension shall be read-
than 8 inches (203 mm) from the inside surface of ily distinguishable from the surrounding floor area. Listed
the nearest flue lining.
and labeled hearth extensions shall comply with UL 1618.

For SI: 1 inch = 25.4 mm.
FIGURE R1003.18
CLEARANCE FROM COMBUSTIBLES

2018 INTERNATIONAL RESIDENTIAL CODE ® 455
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