Page 472 - 2018_IRC

CHAPTER 10

CHIMNEYS AND FIREPLACES

User note:
About this chapter: Chapter 10 contains requirements for the construction, seismic reinforcing and anchorage of masonry chimneys and
fireplaces; and establishes standards for the use and installation of factory-built chimneys, fireplaces and masonry heaters. Chimneys and
fireplaces constructed of masonry rely on prescriptive requirements for the details of their construction; factory-built versions rely on the listing
and labeling method of approval.

SECTION R1001 above grade, except where constructed completely within the
MASONRY FIREPLACES exterior walls. Anchorage shall conform to the requirements
R1001.1 General. Masonry fireplaces shall be constructed in of Section R1001.4.1.
accordance with this section and the applicable provisions of R1001.4.1 Anchorage. Two / -inch by 1-inch (5 mm by
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Chapters 3 and 4. 25 mm) straps shall be embedded not less than 12 inches
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R1001.2 Footings and foundations. Footings for masonry (305 mm) into the chimney. Straps shall be hooked around
fireplaces and their chimneys shall be constructed of concrete the outer bars and extend 6 inches (152 mm) beyond the
or solid masonry not less than 12 inches (305 mm) thick and bend. Each strap shall be fastened to not less than four
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shall extend not less than 6 inches (152 mm) beyond the face of floor ceiling or floor joists or rafters with two / -inch
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the fireplace or foundation wall on all sides. Footings shall be (12.7 mm) bolts.
founded on natural, undisturbed earth or engineered fill below
frost depth. In areas not subjected to freezing, footings shall be R1001.4.1.1 Cold-formed steel framing. Where cold-
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not less than 12 inches (305 mm) below finished grade. formed steel framing is used, the location where the / -
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inch (12.7 mm) bolts are used to attach the straps to the
R1001.2.1 Ash dump cleanout. Cleanout openings framing shall be reinforced with not less than a 3-inch
located within foundation walls below fireboxes, where  3-inch  0.229-inch (76 mm  76 mm  5.8 mm)
provided, shall be equipped with ferrous metal or masonry steel plate on top of the strap that is screwed to the
doors and frames constructed to remain tightly closed framing with not fewer than seven No. 6 screws for
except when in use. Cleanouts shall be located to allow each bolt.
access so that ash removal will not create a hazard to com-
bustible materials. R1001.5 Firebox walls. Masonry fireboxes shall be con-
structed of solid masonry units, hollow masonry units grouted
R1001.3 Seismic reinforcing. Masonry or concrete chim- solid, stone or concrete. Where a lining of firebrick not less
neys in Seismic Design Category D , D or D shall be rein- than 2 inches (51 mm) thick or other approved lining is pro-
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forced. Reinforcing shall conform to the requirements set vided, the minimum thickness of back and sidewalls shall
forth in Table R1001.1 and Section R606.
each be 8 inches (203 mm) of solid masonry, including the
R1001.3.1 Vertical reinforcing. For chimneys up to 40 lining. The width of joints between firebricks shall not be
inches (1016 mm) wide, four No. 4 continuous vertical greater than / inch (6.4 mm). Where a lining is not provided,
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bars shall be placed between wythes of solid masonry or the total minimum thickness of back and side walls shall be
within the cells of hollow unit masonry and grouted in 10 inches (254 mm) of solid masonry. Firebrick shall con-
accordance with Section R606. Grout shall be prevented form to ASTM C27 or C1261 and shall be laid with medium-
from bonding with the flue liner so that the flue liner is duty refractory mortar conforming to ASTM C199.
free to move with thermal expansion. For chimneys more
than 40 inches (1016 mm) wide, two additional No. 4 ver- R1001.5.1 Steel fireplace units. Installation of steel fire-
tical bars shall be provided for each additional flue incor- place units with solid masonry to form a masonry fireplace
porated into the chimney or for each additional 40 inches is permitted where installed either in accordance with the
(1016 mm) in width or fraction thereof. requirements of their listing or the requirements of this
section. Steel fireplace units incorporating a steel firebox
R1001.3.2 Horizontal reinforcing. Vertical reinforce- lining shall be constructed with steel not less than / inch
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ment shall be placed within / -inch (6.4 mm) ties, or other (6.4 mm) thick, and an air-circulating chamber that is
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reinforcing of equivalent net cross-sectional area, placed ducted to the interior of the building. The firebox lining
in the bed joints in accordance with Section R606 at not shall be encased with solid masonry to provide a total
less than every 18 inches (457 mm) of vertical height. Two thickness at the back and sides of not less than 8 inches
such ties shall be installed at each bend in the vertical bars. (203 mm), of which not less than 4 inches (102 mm) shall
R1001.4 Seismic anchorage. Masonry or concrete chimneys be of solid masonry or concrete. Circulating air ducts used
in Seismic Design Category D , D or D shall be anchored at with steel fireplace units shall be constructed of metal or
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each floor, ceiling or roof line more than 6 feet (1829 mm) masonry.
2018 INTERNATIONAL RESIDENTIAL CODE ® 447
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