§ Chapter 17 IRC 2021
Combustion Air
8 entries from Chapter 17 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
M1701.1
Fuel-Burning Appliances Need Adequate Combustion Air
M1701.1
What is combustion air and why does my furnace or water heater need it?
What is combustion air and why does my furnace or water heater need it?
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M1701.2
Confined Spaces Need Combustion Air Openings or Another Approved Method
M1701.2
How do I know if a mechanical room is confined or unconfined?
How do I know if a mechanical room is confined or unconfined?
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M1701.4
Combustion Air Must Account for Exhaust and Depressurization
M1701.4
Can exhaust fans cause backdrafting of a water heater?
Can exhaust fans cause backdrafting of a water heater?
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M1702.1
Indoor Combustion Air Is Allowed Only When the Space Qualifies
M1702.1
Can combustion air come from inside the house?
Can combustion air come from inside the house?
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M1702.2
Outdoor Combustion Air Openings Must Be Sized by Method and Appliance Input
M1702.2
How big do outside combustion air openings need to be?
How big do outside combustion air openings need to be?
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M1702.3
Combustion Air Openings Need High and Low Placement When Required
M1702.3
Where should high and low combustion air openings be located?
Where should high and low combustion air openings be located?
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M1702.4
Combustion Air Ducts Must Be Approved and Kept Open
M1702.4
Can a combustion air duct run through an attic or crawl space?
Can a combustion air duct run through an attic or crawl space?
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M1703.1
Engineered Combustion Air Systems Can Be Approved
M1703.1
Can an engineer design a different combustion air system?
Can an engineer design a different combustion air system?
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