Page 478 - 2018_IRC

CHIMNEYS AND FIREPLACES

R1003.11.3 Gas appliances. Flue lining systems for gas between adjacent flue linings. The masonry wythes shall be
appliances shall be in accordance with Chapter 24. not less than 4 inches (102 mm) thick and bonded into the
walls of the chimney.
R1003.11.4 Pellet fuel-burning appliances. Flue lining
and vent systems for use in masonry chimneys with pellet Exception: Where venting only one appliance, two flues
fuel-burning appliances shall be limited to the following: shall be permitted to adjoin each other in the same chim-
ney with only the flue lining separation between them. The
1. Flue lining systems complying with Section
R1003.11.1. joints of the adjacent flue linings shall be staggered not
less than 4 inches (102 mm).
2. Pellet vents listed for installation within masonry R1003.14 Flue area (appliance). Chimney flues shall not be
chimneys (see Section R1003.11.6 for marking).
smaller in area than that of the area of the connector from the
R1003.11.5 Oil-fired appliances approved for use with appliance [see Tables R1003.14(1) and R1003.14(2)]. The
Type L vent. Flue lining and vent systems for use in sizing of a chimney flue to which multiple appliance venting
masonry chimneys with oil-fired appliances approved for systems are connected shall be in accordance with Section
use with Type L vent shall be limited to the following: M1805.3.
1. Flue lining systems complying with Section TABLE R1003.14(1)
a
R1003.11.1. NET CROSS-SECTIONAL AREA OF ROUND FLUE SIZES
FLUE SIZE, INSIDE DIAMETER CROSS-SECTIONAL AREA
2. Listed chimney liners complying with UL 641 (see (inches) (square inches)
Section R1003.11.6 for marking). 6 2 8
R1003.11.6 Notice of usage. Where a flue is relined with 7 3 8
a material not complying with Section R1003.11.1, the
chimney shall be plainly and permanently identified by a 8 5 0
label attached to a wall, ceiling or other conspicuous loca- 10 78
tion adjacent to where the connector enters the chimney. 10 / 90
3
The label shall include the following message or equiva- 4
lent language: 12 113
15 176
THIS CHIMNEY FLUE IS FOR USE ONLY WITH
[TYPE OR CATEGORY OF APPLIANCE] APPLI- 18 254
ANCES THAT BURN [TYPE OF FUEL]. DO NOT For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm . 2
CONNECT OTHER TYPES OF APPLIANCES. a. Flue sizes are based on ASTM C315.
R1003.12 Clay flue lining (installation). Clay flue liners
shall be installed in accordance with ASTM C1283 and TABLE R1003.14(2)
extend from a point not less than 8 inches (203 mm) below NET CROSS-SECTIONAL AREA OF SQUARE
the lowest inlet or, in the case of fireplaces, from the top of AND RECTANGULAR FLUE SIZES
the smoke chamber to a point above the enclosing walls. The FLUE SIZE, OUTSIDE NOMINAL CROSS-SECTIONAL AREA
lining shall be carried up vertically, with a slope not greater DIMENSIONS (inches) (square inches)
than 30 degrees (0.52 rad) from the vertical. 4.5 × 8.5 23
Clay flue liners shall be laid in medium-duty water insolu- 4.5 × 13 34
ble refractory mortar conforming to ASTM C199 with tight 8 × 8 42

mortar joints left smooth on the inside and installed to main- 8.5 × 8.5 49
tain an airspace or insulation not to exceed the thickness of
the flue liner separating the flue liners from the interior face 8 × 12 67
of the chimney masonry walls. Flue liners shall be supported 8.5 × 13 76
on all sides. Only enough mortar shall be placed to make the 12 × 12 102
joint and hold the liners in position.
8.5 × 18 101
R1003.12.1 Listed materials. Listed materials used as 13 × 13 127
flue linings shall be installed in accordance with the terms
of their listings and manufacturer’s instructions. 12 × 16 131
R1003.12.2 Space around lining. The space surrounding 13 × 18 173
a chimney lining system or vent installed within a 16 × 16 181
masonry chimney shall not be used to vent any other 16 × 20 222
appliance.
18 × 18 233
Exception: This shall not prevent the installation of a
separate flue lining in accordance with the manufac- 20 × 20 298
turer’s instructions. 20 × 24 335
R1003.13 Multiple flues. Where two or more flues are 24 × 24 431
located in the same chimney, masonry wythes shall be built For SI: 1 inch = 25.4 mm, 1 square inch = 645.16 mm . 2

2018 INTERNATIONAL RESIDENTIAL CODE ® 453
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