CODES

ADOPTS WITH AMENDMENTS:

International Residential Code 2015 (IRC 2015)

Part I ‒ Administrative

Chapter 1 Scope and Administration

Part II ‒ Definitions

Chapter 2 Definitions

Part III ‒ Building Planning and Construction

Chapter 3 Building Planning

Chapter 4 Foundations

Chapter 5 Floors

Chapter 6 Wall Construction

Chapter 7 Wall Covering

Chapter 8 Roof-Ceiling Construction

Chapter 9 Roof Assemblies

Chapter 10 Chimneys and Fireplaces

Part IV ‒ Energy Conservation

Chapter 11 [RE] Energy Efficiency

Part V ‒ Mechanical

Chapter 12 Mechanical Administration

Chapter 13 General Mechanical System Requirements

Chapter 14 Heating and Cooling Equipment and Appliances

Chapter 15 Exhaust Systems

Chapter 16 Duct Systems

Chapter 17 Combustion Air

Chapter 18 Chimneys and Vents

Chapter 19 Special Appliances, Equipment and Systems

Chapter 20 Boilers and Water Heaters

Chapter 21 Hydronic Piping

Chapter 22 Special Fuel oil Piping and Storage Systems

Chapter 23 Solar Thermal Energy Systems

Part VI ‒ Fuel Gas

Chapter 24 Fuel Gas

Part VII ‒ Plumbing

Chapter 25 Plumbing Administration

Chapter 26 General Plumbing Requirements

Chapter 27 Plumbing Fixtures

Chapter 28 Water Heaters

Chapter 29 Water Supply and Distribution

Chapter 30 Sanitary Drainage

Chapter 31 Vents

Chapter 32 Traps

Chapter 33 Storm Drainage

Part VIII ‒ Electrical

Chapter 34 General Requirements

Chapter 34 GENERAL REQUIREMENTS

Chapter 35 Electrical Definitions

Chapter 35 ELECTRICAL DEFINITIONS

Chapter 36 Services

Chapter 36 SERVICES

Chapter 37 Branch Circuit and Feeder Requirements

Chapter 37 BRANCH CIRCUIT AND FEEDER REQUIREMENTS

Chapter 38 Wiring Methods

Chapter 38 WIRING METHODS

Chapter 39 Power and Lighting Distribution

Chapter 39 POWER AND LIGHTING DISTRIBUTION

Chapter 40 Devices and Luminaires

Chapter 40 DEVICES AND LUMINAIRES

Chapter 41 Appliance Installation

Chapter 41 APPLIANCE INSTALLATION

Chapter 42 Swimming Pools

Chapter 42 SWIMMING POOLS

Chapter 43 Class 2 Remote-Control, Signaling and Power-Limited Circuits

Chapter 43 CLASS 2 REMOTE-CONTROL, SIGNALING AND POWER-LIMITED CIRCUITS

Part IX ‒ Referenced Standards

Chapter 44 Referenced Standards

Chapter 45 HIGH WIND ZONES

Chapter 46 COASTAL AND FLOOD PLAIN CONSTRUCTION STANDARDS

Appendix A Sizing and Capacities of Gas Piping

Appendix B Sizing of Venting Systems Serving Appliances Equipped With Draft Hoods, Category I Appliances, and Appliances Listed for Use With Type B Vents

Appendix C Exit Terminals of Mechanical Draft and Direct-Vent Venting Systems

Appendix D Recommended Procedure for Safety Inspection of an Existing Appliance Installation

Appendix E Manufactured Housing Used as Dwellings

Appendix E (E-1 THROUGH E-4)
RESIDENTIAL REQUIREMENTS FOR ENERGY CONSERVATION

Appendix F Radon Control Methods

Appendix G Piping Standards for Various Applications

Appendix H Patio Covers

Appendix I Private Sewage Disposal

Appendix J Existing Buildings and Structures

Appendix J EXISTING BUILDINGS AND STRUCTURES

Appendix K Sound Transmission

Appendix L Permit Fees

Appendix M HOME DAY CARE—R-3 OCCUPANCY

Appendix M WOOD DECKS

Appendix N Venting Methods

Appendix O Automatic Vehicular Gates

Appendix O FOAM PLASTIC DIAGRAMS

Appendix P Sizing of Water Piping System

Appendix Q Reserved

Appendix Q DISCONTINUOUS FOOTINGS

Appendix R Light Straw-Clay Construction

Appendix S Strawbale Construction

Appendix T Recommended Procedure for Worst-Case Testing of Atmospheric Venting Systems Under N1102.4 or N1105 Conditions ≤ 5ACH50

Appendix U SOLAR-READY PROVISIONS—DETACHED ONE- AND TWO-FAMILY DWELLINGS, MULTIPLE SINGLE- FAMILY DWELLINGS (TOWNHOUSES)

Appendix V SWIMMING POOLS, SPAS AND HOT TUBS

Appendix W BASIC LOAD ESTIMATING

Chapter 18 Chimneys and Vents

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
User note: Code change proposals to this chapter will be considered by the IRC ‒ Plumbing and Mechanical Code Development Committee during the 2015 (Group A) Code Development Cycle. The text of this chapter is extracted from the 2018 edition of the North Carolina Mechanical Code and has been modified where necessary to conform to the scope of application of the North Carolina Residential Code for One- and Two-Family Dwellings. The section numbers appearing in parentheses after each section number are the section numbers of the corresponding text in the North Carolina Mechanical Code.

M1801.1 (801.1) Venting required

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Fuel-burning appliances shall be vented to the outdoors in accordance with their listing and label and manufacturer's installation instructions except appliances listed and labeled for unvented use. Venting systems shall consist of approved chimneys or vents, or venting assemblies that are integral parts of labeled appliances. Gas-fired appliances shall be vented in accordance with Chapter 24.
A venting system shall satisfy the draft requirements of the appliance in accordance with the manufacturer's installation instructions, and shall be constructed and installed to develop a positive flow to convey combustion products to the outside atmosphere.
Where an appliance is permanently disconnected from an existing chimney or vent, or where an appliance is connected to an existing chimney or vent during the process of a new installation, the chimney or vent shall comply with Sections M1801.3.1 through M1801.3.4.
The chimney or vent shall be resized as necessary to control flue gas condensation in the interior of the chimney or vent and to provide the appliance, or appliances served, with the required draft. For the venting of oil-fired appliances to masonry chimneys, the resizing shall be done in accordance with NFPA 31.
The flue gas passageway shall be free of obstructions and combustible deposits and shall be cleaned if previously used for venting a solid or liquid fuel-burning appliance or fireplace. The flue liner, chimney inner wall or vent inner wall shall be continuous and free of cracks, gaps, perforations, or other damage or deterioration that would allow the escape of combustion products, including gases, moisture and creosote.

M1801.3.3 (801.13) Cleanout

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Masonry chimneys shall be provided with a cleanout opening complying with Section R1003.17.

M1801.3.4 (801.18.4) Clearances

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Chimneys and vents shall have airspace clearance to combustibles in accordance with this code and the chimney or vent manufacturer's installation instructions.

Exception: Masonry chimneys equipped with a chimney lining system tested and listed for installation in chimneys in contact with combustibles in accordance with UL 1777, and installed in accordance with the manufacturer's instructions, shall not be required to have a clearance between combustible materials and exterior surfaces of the masonry chimney. Noncombustible firestopping shall be provided in accordance with this code.

M1801.4 (801.17) Space around lining

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The space surrounding a flue lining system or other vent installed within a masonry chimney shall not be used to vent any other appliance. This shall not prevent the installation of a separate flue lining in accordance with the manufacturer's installation instructions and this code.
A mechanical draft system shall be used only with appliances listed and labeled for such use. Provisions shall be made to prevent the flow of fuel to the equipment when the draft system is not operating. Forced draft systems and portions of induced draft systems under positive pressure during operation shall be designed and installed to prevent leakage of flue gases into a building.
Direct-vent appliances shall be installed in accordance with the manufacturer's instructions.
Venting systems shall be adequately supported for the weight of the material used.
Chimneys, vents and vent connectors shall not extend into or through supply and return air ducts or plenums.
Vent and chimney installations shall be fireblocked in accordance with Section R602.8.
Unused openings in any venting system shall be closed or capped.
Two or more listed and labeled appliances connected to a common natural draft venting system shall comply with the following requirements:

1. Appliances that are connected to common venting systems shall be located on the same floor of the dwelling.

Exception: Engineered systems as provided for in Section G2427.

2. Inlets to common venting systems shall be offset such that no portion of an inlet is opposite another inlet.

3. Connectors serving appliances operating under a natural draft shall not be connected to any portion of a mechanical draft system operating under positive pressure.
A solid fuel-burning appliance or fireplace shall not connect to a chimney passageway venting another appliance.
Draft hoods shall be located in the same room or space as the combustion air openings for the appliances.
Vent dampers shall comply with Sections M1802.2.1 and M1802.2.2.
Manually operated dampers shall not be installed except in connectors or chimneys serving solid fuel-burning appliances.
Automatically operated dampers shall conform to UL 17 and be installed in accordance with the terms of their listing and label. The installation shall prevent firing of the burner when the damper is not opened to a safe position.
Draft regulators shall be provided for oil-fired appliances that must be connected to a chimney. Draft regulators provided for solid fuel-burning appliances to reduce draft intensity shall be installed and set in accordance with the manufacturer's installation instructions.
Where required, draft regulators shall be installed in the same room or enclosure as the appliance so that a difference in pressure will not exist between the air at the regulator and the combustion air supply.
Connectors shall be used to connect fuel-burning appliances to a vertical chimney or vent except where the chimney or vent is attached directly to the appliance.

M1803.2 (803.9) Connectors for oil and solid fuel appliances

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Connectors for oil and solid fuel-burning appliances shall be constructed of factory-built chimney material, Type L vent material or single-wall metal pipe having resistance to corrosion and heat and thickness not less than that of galvanized steel as specified in Table M1803.2.

TABLE M1803.2 [803.9(1)] THICKNESS FOR SINGLE-WALL METAL PIPE CONNECTORS

DIAMETER OF
CONNECTOR (inches)
GALVANIZED SHEET
METAL GAGE
NUMBER
MINIMUM THICKNESS
(inch)
Less than 6 26 0.019
6 to 10 24 0.024
Over 10 through 16 22 0.029

For SI: 1 inch = 25.4 mm.

M1803.3 (803.10.5) Installation

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Vent and chimney connectors shall be installed in accordance with the manufacturer's instructions and within the space where the appliance is located. Appliances shall be located as close as practical to the vent or chimney. Connectors shall be as short and straight as possible and installed with a slope of not less than 1/4 inch (6 mm) rise per foot of run. Connectors shall be securely supported and joints shall be fastened with sheet metal screws or rivets. Devices that obstruct the flow of flue gases shall not be installed in a connector unless listed and labeled or approved for such installations.

M1803.3.1 (803.10.4) Floor, ceiling and wall penetrations

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A chimney connector or vent connector shall not pass through any floor or ceiling. A chimney connector or vent connector shall not pass through a wall or partition unless the connector is listed and labeled for wall pass-through, or is routed through a device listed and labeled for wall pass-through and is installed in accordance with the conditions of its listing and label. Connectors for oil-fired appliances listed and labeled for Type L vents, passing through walls or partitions shall be in accordance with the following:

1. Type L vent material for oil appliances shall be installed with not less than listed and labeled clearances to combustible material.

2. Single-wall metal pipe shall be guarded by a ventilated metal thimble not less than 4 inches (102 mm) larger in diameter than the vent connector. A minimum 6 inches (152 mm) of clearance shall be maintained between the thimble and combustibles.
The horizontal run of an uninsulated connector to a natural draft chimney shall not exceed 75 percent of the height of the vertical portion of the chimney above the connector. The horizontal run of a listed connector to a natural draft chimney shall not exceed 100 percent of the height of the vertical portion of the chimney above the connector.
A connector shall not be smaller than the flue collar of the appliance.

Exception: Where installed in accordance with the appliance manufacturer's instructions.

M1803.3.4 (803.10.6) Clearance

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Connectors shall be installed with clearance to combustibles as set forth in Table M1803.3.4 or Table M1803.3.5. Reduced clearances to combustible materials shall be in accordance with Table M1306.2 and Figure M1306.1.

TABLE M1803.3.4 CHIMNEY AND VENT CONNECTOR CLEARANCES TO COMBUSTIBLE MATERIALSa

TYPE OF CONNECTOR MINIMUM
CLEARANCE
(inches)
Single-wall metal pipe connectors:
Oil and solid-fuel appliances 18
Oil appliances listed for use with Type L vents 9
Type L vent piping connectors:
Oil and solid-fuel appliances 9
Oil appliances listed for use with Type L vents 3b

For SI: 1 inch = 25.4 mm.
a. These minimum clearances apply to unlisted single-wall chimney and vent connectors. Reduction of required clearances is permitted as in Table M1306.2.
b. Where listed Type L vent piping is used, the clearance shall be in accordance with the vent listing.

M1803.3.5 Access

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
The entire length of a connector shall be accessible for inspection, cleaning and replacement.

TABLE M1803.3.5 (803.10.4)
CHIMNEY CONNECTOR SYSTEMS AND CLEARANCES TO COMBUSTIBLE WALL MATERIALS FOR DOMESTIC HEATING APPLIANCESa, b, c, d
System A
(12-inch clearance)
A 3.5-inch-thick brick wall shall be framed into the combustible wall. An 0.625-inch-thick fire-clay liner (ASTM C315 or equivalent)e shall be firmly cemented in the center of the brick wall maintaining a 12-inch clearance to combustibles. The clay liner shall run from the outer surface of the bricks to the inner surface of the chimney liner.
System B
(9-inch clearance)
A labeled solid-insulated factory-built chimney section (1-inch insulation) the same inside diameter as the connector shall be utilized. Sheet steel supports cut to maintain a 9-inch clearance to combustibles shall be fastened to the wall surface and to the chimney section. Fasteners shall not penetrate the chimney flue liner. The chimney length shall be flush with the masonry chimney liner and sealed to the masonry with water-insoluble refractory cement. Chimney manufacturers’ parts shall be utilized to securely fasten the chimney connector to the chimney section.
System C
(6-inch clearance)
A steel ventilated thimble having a minimum thickness of 0.0236 inch (No. 24 gage) having two 1-inch air channels shall be installed with a steel chimney connector. Steel supports shall be cut to maintain a 6-inch clearance between the thimble and combustibles. The chimney connector and steel supports shall have a minimum thickness of 0.0236 inch (No. 24 gage). One side of the support shall be fastened to the wall on all sides. Glass-fiber insulation shall fill the 6-inch space between the thimble and the supports.
System D
(2-inch clearance)
A labeled solid-insulated factory-built chimney section (1-inch insulation) with a diameter 2 inches larger than the chimney connector shall be installed with a steel chimney connector having a minimum thickness of 0.0236 inch (24 gage). Sheet steel supports shall be positioned to maintain a 2-inch clearance to combustibles and to hold the chimney connector to ensure that a 1-inch airspace surrounds the chimney connector through the chimney section. The steel support shall be fastened to the wall on all sides and the chimney section shall be fastened to the supports. Fasteners shall not penetrate the liner of the chimney section.
For SI: 1 inch = 25.4 mm, 1.0 Btu • in/ft2 • h • °F = 0.144 W/m2 • K.
  1. Insulation material that is part of the wall pass-through system shall be noncombustible and shall have a thermal conductivity of 1.0 Btu × in/ft2 • h • °F or less.
  2. All clearances and thicknesses are minimums.
  3. Materials utilized to seal penetrations for the connector shall be noncombustible.
  4. Connectors for all systems except System B shall extend through the wall pass-through system to the inner face of the flue liner.
  5. ASTM C315.
Connection of appliances to chimney flues serving fireplaces shall comply with Sections M1803.4.1 through M1803.4.4.
A noncombustible seal shall be provided below the point of connection to prevent entry of room air into the flue. Means shall be provided for access to the flue for inspection and cleaning.
A different appliance shall not be connected to a flue serving a factory-built fireplace unless the appliance is specifically listed for such an installation. The connection shall be made in conformance with the appliance manufacturer's instructions.
A connector shall extend from the appliance to the flue serving a masonry fireplace to convey the flue gases directly into the flue. The connector shall be accessible or removable for inspection and cleaning of both the connector and the flue. Listed direct-connection devices shall be installed in accordance with their listing.
The size of the fireplace flue shall be in accordance with Section M1805.3.1.
Appliances shall be provided with a listed and labeled venting system as set forth in Table M1804.1.

TABLE M1804.1 VENT SELECTION CHART

VENT TYPES APPLIANCE TYPES
Type L oil vents Oil-burning appliances listed and labeled for
venting with Type L vents
Pellet vents Pellet fuel-burning appliances listed and
labeled for use with pellet vents

M1804.1.1 (801.20) Plastic vent joints

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Plastic pipe and fittings used to vent appliances shall be installed in accordance with the appliance manufacturer’s installation instructions. Solvent cement joints between ABS pipe and fittings shall be cleaned. Solvent cement joints between CPVC pipe and fittings or PVC pipe and fittings shall be primed. The primer shall be a contrasting color, or an ultraviolet primer may be used.
Vent termination shall comply with Sections M1804.2.1 through M1804.2.6.
Vents passing through a roof shall extend through flashing and terminate in accordance with the manufacturer's installation requirements.
Decorative shrouds shall not be installed at the termination of vents except where the shrouds are listed and labeled for use with the specific venting system and are installed in accordance with the manufacturer's instructions.
Vents for natural draft appliances shall terminate not less than 5 feet (1524 mm) above the highest connected appliance outlet, and natural draft gas vents serving wall furnaces shall terminate at an elevation not less than 12 feet (3658 mm) above the bottom of the furnace.
Type L venting systems shall conform to UL 641 and shall terminate with a listed and labeled cap in accordance with the vent manufacturer's installation instructions not less than 2 feet (610 mm) above the roof and not less than 2 feet (610 mm) above any portion of the building within 10 feet (3048 mm).
Vent terminals for direct-vent appliances shall be installed in accordance with the manufacturer's instructions.

M1804.2.6 Mechanical Draft Systems

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Mechanical draft systems shall comply with UL 378 and shall be installed in accordance with their listing, the manufacturer's instructions and, except for direct-vent appliances, the following requirements:

1. The vent terminal shall be located not less than 3 feet (914 mm) above a forced air inlet located within 10 feet (3048 mm).

2. The vent terminal shall be located not less than 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from, or 1 foot (305 mm) above any door, window or gravity air inlet into a dwelling.

3. The vent termination point shall be located not closer than 3 feet (914 mm) to an interior corner formed by two walls perpendicular to each other.

4. The bottom of the vent terminal shall be located not less than 12 inches (305 mm) above finished ground level.

5. The vent termination shall not be mounted directly above or within 3 feet (914 mm) horizontally of an oil tank vent or gas meter.

6. Power exhauster terminations shall be located not less than 10 feet (3048 mm) from lot lines and adjacent buildings.

7. The discharge shall be directed away from the building.
Sections M1804.2.6.1 through M1804.2.6.3.

M1804.2.6.1 (804.3.4) Horizontal terminations

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Vertical terminations shall comply with the following requirements:
  1. Where located adjacent to walkways, the termination of mechanical draft systems shall be not less than 7 feet (2134 mm) above the level of the walkway.
  2. Vents shall terminate not less than 3 feet (914 mm) above any forced air inlet located within 10 feet (3048 mm).
  3. The vent system shall terminate not less than 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from or 1 foot (305 mm) above any door, window or gravity air inlet into the building.
  4. The vent termination point shall not be located closer than 3 feet (914 mm) to an interior corner formed by two walls perpendicular to each other.
  5. The vent termination shall not be mounted directly above or within 3 feet (914 mm) horizontally from an oil tank vent or gas meter.
  6. The bottom of the vent termination shall be located not less than 12 inches (305 mm) above finished grade.

M1804.2.6.2 (804.3.5) Vertical terminations

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Vertical terminations shall comply with the following requirements:
  1. Where located adjacent to walkways, the termination of mechanical draft systems shall be not less than 7 feet (2134 mm) above the level of the walkway.
  2. Vents shall terminate not less than 3 feet (914 mm) above any forced air inlet located within 10 feet (3048 mm) horizontally.
  3. Where the vent termination is located below an adjacent roof structure, the termination point shall be located not less than 3 feet (914 mm) from such structure.
  4. The vent shall terminate not less than 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from or 1 foot (305 mm) above any door, window or gravity air inlet for the building.
  5. A vent cap shall be installed to prevent rain from entering the vent system.
  6. The vent termination shall be located not less than 3 feet (914 mm) horizontally from any portion of the roof structure.

M1804.2.6.3 (804.3.8) Mechanical draft systems for manually fired appliances and fireplaces

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A mechanical draft system shall be permitted to be used with manually fired appliances and fireplaces where such system complies with all of the following requirements:
  1. The mechanical draft device shall be listed and labeled in accordance with UL 378, and shall be installed in accordance with the manufacturer’s instructions.
  2. A device shall be installed that produces visible and audible warning upon failure of the mechanical draft device or loss of electrical power, at any time that the mechanical draft device is turned on. This device shall be equipped with a battery backup if it receives power from the building wiring.
  3. A smoke detector shall be installed in the room with the appliance or fireplace. This device shall be equipped with a battery backup if it receives power from the building wiring.
Type L and pellet vents shall be installed in accordance with the terms of their listing and label and the manufacturer's instructions.
An individual vent for a single appliance shall have a cross-sectional area equal to or greater than the area of the connector to the appliance, but not less than 7 square inches (4515 mm2) except where the vent is an integral part of a listed and labeled appliance.
Appliance and equipment vent terminals shall be located such that doors cannot swing within 12 inches (305 mm) horizontally of the vent terminals. Door stops or closers shall not be installed to obtain this clearance.
Masonry and factory-built chimneys shall be built and installed in accordance with Sections R1003 and R1005, respectively. Flue lining for masonry chimneys shall comply with Section R1003.11.

M1805.2 (803.10.3) Masonry chimney connection

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
A chimney connector shall enter a masonry chimney not less than 6 inches (152 mm) above the bottom of the chimney. Where it is not possible to locate the connector entry at least 6 inches (152 mm) above the bottom of the chimney flue, a cleanout shall be provided by installing a capped tee in the connector next to the chimney. A connector entering a masonry chimney shall extend through, but not beyond, the wall and shall be flush with the inner face of the liner. Connectors, or thimbles where used, shall be firmly cemented into the masonry.
The effective area of a natural draft chimney flue for one appliance shall be not less than the area of the connector to the appliance. The area of chimney flues connected to more than one appliance shall be not less than the area of the largest connector plus 50 percent of the areas of additional chimney connectors.

Exception: Chimney flues serving oil-fired appliances sized in accordance with NFPA 31.
Except where otherwise specified in the manufacturer's installation instructions, the cross-sectional area of a flue connected to a solid-fuel-burning appliance shall be not less than the area of the flue collar or connector, and not larger than three times the area of the flue collar.

M1805.4 (805.6) Decorative shrouds

AMENDMENT
This section has been amended at the state or city level. Amendments are shown in green text.
Decorative shrouds shall not be installed at the termination of factory-built chimneys except where such shrouds are listed and labeled for use with the specific factory-built chimney system and are installed in accordance with manufacturer’s installation instructions.
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