§ Chapter 18 IRC 2021
Chimneys and Vents ? Mechanical
8 entries from Chapter 18 of IRC 2021, organized by section number. Each entry covers what the code requires, why it exists, what inspectors look for, and common mistakes.
§ 01 Sections
All 8 entries.
Sorted by section number. Click any row for the full entry — answer, requirements, edition diff, related sections.
Section
Title
Question
M1801.1
Fuel-Burning Appliances Need an Approved Venting System
M1801.1
Does every gas furnace or water heater need a chimney or vent?
Does every gas furnace or water heater need a chimney or vent?
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M1801.3
Masonry Chimneys Used for Appliances Must Be Suitable and Lined
M1801.3
Can I vent a gas water heater into an old masonry chimney?
Can I vent a gas water heater into an old masonry chimney?
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M1801.3.1
Vent Size Must Match the Appliance and Venting Tables
M1801.3.1
Can I reduce the vent size from my furnace or water heater?
Can I reduce the vent size from my furnace or water heater?
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M1801.7
Vent Connectors Need Support and Proper Slope
M1801.7
How should a furnace vent connector be supported?
How should a furnace vent connector be supported?
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M1803.3
Vent Connectors Cannot Be Treated Like Listed Vents
M1803.3
Can single-wall vent pipe pass through a wall or ceiling?
Can single-wall vent pipe pass through a wall or ceiling?
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M1803.3.4
Vent Connectors Need Required Clearance to Combustibles
M1803.3.4
How much clearance does a vent connector need from wood framing?
How much clearance does a vent connector need from wood framing?
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M1804.2
Type B Vents Must Follow Listing Clearances
M1804.2
Can Type B vent pipe touch insulation or framing?
Can Type B vent pipe touch insulation or framing?
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M1804.2.6
Mechanical Vents Need Code-Compliant Roof Termination Height
M1804.2.6
How high does a furnace or water heater vent have to terminate above the roof?
How high does a furnace or water heater vent have to terminate above the roof?
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