|State and local housing, property maintenance,
and building codes contain a wide array of legal requirements pertaining
to housing construction and maintenance. Below are listed
provisions found in model codes that address ventilation. The
opening file on Housing and
Building Codes features a chart listing code provisions on
several healthy home attributes.
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
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
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
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
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
IMC § 501.2: Exhaust Systems/Independent System Required.
Mechanical exhaust systems for bathrooms must be independent of other
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
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
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.)
- 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.