Page 479 - 2018_IRC

CHIMNEYS AND FIREPLACES

R1003.15 Flue area (masonry fireplace). Flue sizing for R1003.15.2 Option 2. The minimum net cross-sectional
chimneys serving fireplaces shall be in accordance with Sec- area of the chimney flue shall be determined in accordance
tion R1003.15.1 or R1003.15.2. with Figure R1003.15.2. A flue size providing not less
R1003.15.1 Option 1. Round chimney flues shall have a than the equivalent net cross-sectional area shall be used.
minimum net cross-sectional area of not less than one- Cross-sectional areas of clay flue linings are shown in
twelfth of the fireplace opening. Square chimney flues Tables R1003.14(1) and R1003.14(2) or as provided by
shall have a minimum net cross-sectional area of one-tenth the manufacturer or as measured in the field. The height of
of the fireplace opening. Rectangular chimney flues with the chimney shall be measured from the firebox floor to
an aspect ratio less than 2 to 1 shall have a minimum net the top of the chimney flue.
cross-sectional area of one-tenth of the fireplace opening. R1003.16 Inlet. Inlets to masonry chimneys shall enter from
Rectangular chimney flues with an aspect ratio of 2 to 1 or the side. Inlets shall have a thimble of fireclay, rigid refrac-
more shall have a minimum net cross-sectional area of tory material or metal that will prevent the connector from
one-eighth of the fireplace opening. Cross-sectional areas pulling out of the inlet or from extending beyond the wall of
of clay flue linings are shown in Tables R1003.14(1) and the liner.
R1003.14(2) or as provided by the manufacturer or as
measured in the field.

3000

2800

2600

2400

224 269 2200
2000

187 214 1800
MIN. CROSS-SECTIONAL AREA (SQ. IN.) 140 168 1400
1600

1200
110
124
1000

76
600
70
82
53 91 800
58
400
32 37
200
20
21
17
18
19
ROUND FLUES SQUARE OR RECTANGULAR FLUES 13 14 15 16 HEIGHT, MEASURED FROM FLOOR 22 23 24 25 FIREPLACE OPENING AREA (SQ. IN.)
OF COMBUSTION CHAMBER TO
TOP OF FLUE (FT)
2
For SI: 1 foot = 304.8 mm, 1 square inch = 645.16 mm .
FIGURE R1003.15.2
FLUE SIZES FOR MASONRY CHIMNEYS

454 2018 INTERNATIONAL RESIDENTIAL CODE ®
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