IPMC § 303.11: Chimneys and Towers. Chimneys must be structurally safe and in good repair. (Obstruction of chimneys that serve as a vent for fuel-burning appliances can lead to high levels of carbon monoxide.)

IPMC § 303.13.2: Openable Windows. Windows other than fixed windows must be easily openable. (Open windows provide natural ventilation.)

IPMC § 403.1: Ventilation/Habitable Space. Every habitable space must have at least one openable window.

IPMC § 505.4: Water Heating Facilities. Gas-burning water-heating facilities must not be located in any bathroom, toilet room, bedroom, or other occupied room normally kept closed, unless adequate combustion air is provided. (Asphyxiation can result from inadequate combustion air.)

IPMC § 602.2: Heating Facilities/Residential Occupancies. Cooking appliances may not be used to provide space heating. (Fuel-fired cooking appliances typically are not vented, and therefore discharge combustion products directly to the occupied space. Prolonged use can result in high levels of carbon monoxide and other contaminants, particularly because windows likely will be closed to conserve heat.)

IPMC § 603.2: Removal of Combustion Products. Fuel-burning equipment and appliances must be connected to an approved chimney or vent. (Failure to vent properly can cause build-up of carbon monoxide.)

IPMC § 603.5: Combustion Air. A supply of air for complete combustion of the fuel and for ventilation must be provided for fuel-burning equipment. (Failure to supply adequate air can result in improper draft, soot production, increased carbon monoxide production, and risk of fire or explosion; failure to vent properly can cause build-up of carbon monoxide, high temperatures, and increased risk of fire.)

IRC § 303.1: Light, Ventilation, and Heating/Habitable Rooms. Habitable rooms must be provided with total glazing (window) area of at least eight percent of the room’s floor area. Natural ventilation must be provided through readily controllable windows, doors, etc. Minimum openable area to the outdoors must be four percent of the room’s floor area. Windows need not be openable if they are not needed for emergency exit and a mechanical ventilation system is capable of producing 0.35 air change per hour in the room, or a whole-house ventilation system is installed capable of supplying outdoor air at 15 ft³ per minute per occupant, with occupants computed based on the number of bedrooms.

IRC § 309.1: Garages and Carports/Opening Protection. Openings from a garage into a room used for sleeping purposes are not permitted. (Carbon monoxide fumes or smoke could pose a threat to persons sleeping in the room.)

IRC § 309.2: Garages and Carports/Separation Required. The garage must be separated from its residence by at least ½ inch gypsum board (to prevent carbon monoxide and fumes from other hazardous materials stored in the garage from entering the dwelling).

IBC § 1202.1: Ventilation/General. Buildings must be provided with natural ventilation or mechanical ventilation.

IBC § 1202.2: Ventilation/Attic Spaces. Enclosed attics and rafter spaces formed where ceilings are applied directly to the underside of roofs must be cross-ventilated. Ventilation openings must be protected against the entrance of snow and rain (to prevent the entry of moisture).

IBC § 1202.3: Under-floor Ventilation. Crawl spaces must be cross-ventilated through foundation or exterior walls. In cold climates, ventilation instead can be to the interior (which may help to conserve energy, but could present a problem if high concentrations of radon gas are present). Less ventilation is required if the ground surface is treated with a vapor retardant material.

IBC § 1202.4: Natural Ventilation. Natural ventilation shall be through doors, windows, or other openings to the outdoors. Openings must be readily controllable by occupants.

IBC § 1202.4.1: Ventilation Area Required. Minimum openable area to the outdoors must be four percent of the floor area being ventilated.

IMC § 301.9: Fuel Types. Appliances that comprise part of the building’s mechanical system may not be converted for use with a different type of fuel, unless approved and converted in accordance with the manufacturer’s instructions. (Incorrectly performed fuel conversions can adversely impact the venting of combustion gases.)

IMC § 303.3: Equipment and Appliance Location/Prohibited Locations. Fuel-fired appliances may not be located in bedrooms, bathrooms, or storage closets, unless all combustion air is obtained from the outdoors, or it is a solid fuel-fired appliance not located in an enclosed space. (This is to avoid buildup of combustion gases, or the depletion of oxygen levels.)

IMC § 401.2: Ventilation Required. Every occupied space must be ventilated naturally or mechanically.

IMC § 401.5: Ventilation/Opening Location. Outside air exhaust and intake openings must be located at least 10 feet from lot lines, buildings, and the center of the street (if fronting on the street). (This prevents contaminants from being introduced into the ventilation system, and also prevents exhaust from entering into occupied areas or other buildings.)

IMC § 401.5.1: Ventilation/Intake Openings. Outside air intake openings must be located at least 10 feet from any contaminant sources, such as chimneys, plumbing vents, streets, parking lots, etc.

IMC § 403.2.1: Recirculation of Air. Air may be recirculated only if it exceeds the minimum outdoor airflow rate required under § 403.3. Ventilation air may not be recirculated from one dwelling to another. (Ideally, recirculation would not be allowed between dwelling units (single living units within the same building), in order to prevent the flow of contaminants such as environmental tobacco smoke from one unit to another.)

IMC § 403.3: Ventilation Rate. Ventilation systems must be designed to have the capacity to supply the appropriate corresponding minimum outdoor airflow rate, based upon maximum occupancy load and other factors.

IMC § 501.2: Exhaust Systems/Independent System Required. Mechanical exhaust systems for bathrooms must be independent of other exhaust systems.

IMC § 501.3: Exhaust Systems/Outdoor Discharge. The air removed by a mechanical exhaust system must be discharged to the outdoors, and may not be exhausted to an attic or crawl space.

IMC § 501.4: Exhaust Systems/Pressure Equalization. Mechanical exhaust systems must be designed to remove the quantity of air required to be exhausted. The volume of air supplied must be approximately equal to the volume of air exhausted.

IMC § 505.1: Domestic Kitchen Exhaust Equipment. Domestic range hoods and appliances should be vented to the outdoors, unless adequate natural or mechanical ventilation is provided.

IMC § 512: Subslab Soil Exhaust Systems. Radon mitigation systems are not required, but where they are installed, ducts must be constructed of specified materials, and must terminate at least six inches above the roof. Ducts also must be identified within each floor level.

IMC § 601.3: Duct Systems/Contamination Prevention. Exhaust ducts under positive pressure, chimneys, and vents must not extend into or pass through ducts. (This prevents cross-contamination from exhaust ducts, chimneys, etc. into the HVAC system.)

IMC § 602.1: Plenums/General. A plenum is an enclosed portion of the building designed to allow air movement and serve as part of the air distribution system. Fuel-fired appliances may not be installed within a plenum. (This prevents the spread of combustion products throughout the building and prevents flue gases from being drawn into the plenum space due to negative pressure that can exist in a plenum space.)

IMC § 701.1: Combustion Air/Scope. Chapter 7 of the IMC covers requirements for fuel-burning appliances burning solid or liquid fuel, other than gas-fired appliances, which are covered under the International Fuel Gas Code. Sections 702-707 set forth seven different methods for supplying adequate combustion and dilution air.

IMC § 701.2: Combustion and Dilution Air Required. Every room or space containing a fuel-burning appliance must be provided with combustion and dilution air. (Adequate combustion and dilution air is necessary to ensure complete combustion and proper draft and appliance venting in order to prevent buildup of carbon monoxide and soot, and to ensure proper functioning of appliances.)

IMC § 701.3: Circulation of Air. Mechanical exhaust systems, fireplaces, and other appliances operating in the same room from which combustion or dilution air is drawn must be installed so as to prevent their simultaneous operation from affecting the supply of combustion and dilution air.

IMC § 801.2: Chimneys and Vents/General. Fuel-burning appliances must discharge the products of combustion to a vent or chimney designed for the type of appliance used. (This ensures that combustion products such as carbon monoxide are properly removed from occupied spaces.)

About the Codes

• The IPMC applies to existing residential and commercial structures and premises.

• The IRC regulates the construction, alteration, repair, use, and occupancy of detached one- and two-family dwellings and townhouses not more than three stories high. While the section numbers in the code are preceded by a letter, e.g., “R” for the administrative, definitions, and building, planning, and construction portions of the code, “N” for the energy conservation portion, etc., those prefixes have been omitted from this document.

• The IBC governs new construction in residential buildings four or more stories high.

• The IMC governs the design, installation, maintenance, alteration, and inspection of permanently installed mechanical systems used to control environmental conditions within buildings. The IMC does not require the removal and replacement of existing mechanical systems, although work performed on existing systems must conform to the code’s requirements for new work.