- Item 5.1.1, 5.1.2, 5.1.3 or 5.1.4 shall be met, depending on the air permeability of the insulation directly under the structural roof sheathing.
- Where only air-impermeable insulation is provided, it shall be applied in direct contact with the underside of the structural roof sheathing.
- Where air-permeable insulation is provided inside the building thermal envelope, it shall be installed in accordance with Item 5.1.1. In addition to the air-permeable insulation installed directly below the structural sheathing, rigid board or sheet insulation shall be installed directly above the structural roof sheathing in accordance with the R-values in Table 1202.3 for condensation control.
- Where both air-impermeable and air-permeable insulation are provided, the air-impermeable insulation shall be applied in direct contact with the underside of the structural roof sheathing in accordance with Item 5.1.1 and shall be in accordance with the R-values in Table 1202.3 for condensation control. The air-permeable insulation shall be installed directly under the air-impermeable insulation .
- Alternatively, sufficient rigid board or sheet insulation shall be installed directly above the structural roof sheathing to maintain the monthly average temperature of the underside of the structural roof sheathing above 45°F (7°C). For calculation purposes, an interior air temperature of 68°F (20°C) is assumed and the exterior air temperature is assumed to be the monthly average outside air temperature of the three coldest months.
- Section 1202.3 does not apply to special use structures or enclosures such as swimming pool enclosures, data processing centers, hospitals or art galleries.
- Section 1202.3 does not apply to enclosures in Climate Zones 5 through 8 that are humidified beyond 35 percent during the three coldest months.
CLIMATE ZONE MINIMUM R-VALUE OF AIR-IMPERMEABLE INSULATION a 2B and 3B tile roof only 0 (none required) 1, 2A, 2B, 3A, 3B, 3C R-5 4C R-10 4A, 4B R-15 5 R-20 6 R-25 7 R-30 8 R-35 - Contributes to, but does not supersede, thermal resistance requirements for attic and roof assemblies in Section C402.2.1 of the International Energy Conservation Code.
1202.4 Under-Floor Ventilation
The space between the bottom of the floor joists and the earth under any building except spaces occupied by basements or cellars shall be provided with ventilation in accordance with Section 1202.4.1, 1202.4.2 or 1202.4.3.
1202.4.1 Ventilation Openings
Ventilation openings through foundation walls shall be provided. The openings shall be placed so as to provide cross ventilation of the under-floor space. The net area of ventilation openings shall be in accordance with Section 1202.4.1.1 or 1202.4.1.2. Ventilation openings shall be covered for their height and width with any of the following materials, provided that the least dimension of the covering shall be not greater than 1 /4 inch (6.4 mm):
- Perforated sheet metal plates not less than 0.070 inch (1.8 mm) thick.
- Expanded sheet metal plates not less than 0.047 inch (1.2 mm) thick.
- Cast-iron grilles or gratings.
- Extruded load-bearing vents.
- Hardware cloth of 0.035-inch (0.89 mm) wire or heavier.
- Corrosion-resistant wire mesh, with the least dimension not greater than 1 /8 inch (3.2 mm).
- Operable louvres, where ventilation is provided in accordance with Section 1202.4.1.2.
1202.4.1.1 Ventilation Area for Crawl Spaces With Open Earth Floors
The net area of ventilation openings for crawl spaces with uncovered earth floors shall be not less than 1 square foot for each 150 square feet (0.67 m 2 for each 100 m 2 ) of crawl space area.
1202.4.1.2 Ventilation Area for Crawl Spaces With Covered Floors
The net area of ventilation openings for crawl spaces with the ground surface covered with a Class I vapor retarder shall be not less than 1 square foot for each 1,500 square feet (0.67 m 2 for each 1000 m 2 ) of crawl space area.
1202.4.2 Ventilation in Cold Climates
In extremely cold climates, where a ventilation opening will cause a detrimental loss of energy, ventilation openings to the interior of the structure shall be provided.
1202.4.3 Mechanical Ventilation
Mechanical ventilation shall be provided to crawl spaces where the ground surface is covered with a Class I vapor retarder. Ventilation shall be in accordance with Section 1202.4.3.1 or 1202.4.3.2.
1202.4.3.1 Continuous Mechanical Ventilation
Continuously operated mechanical ventilation shall be provided at a rate of 1.0 cubic foot per minute (cfm) for each 50 square feet (1.02 L/s for each 10 m 2 ) of crawl space ground surface area and the ground surface shall be covered with a Class I vapor retarder.
1202.4.3.2 Conditioned Space
The crawl space shall be conditioned in accordance with the International Mechanical Code and the walls of the crawl space shall be insulated in accordance with the International Energy Conservation Code.
1202.4.4 Flood Hazard Areas
For buildings in flood hazard areas as established in Section 1612.3, the openings for under-floor ventilation shall be deemed as meeting the flood opening requirements of ASCE 24 provided that the ventilation openings are designed and installed in accordance with ASCE 24.
1202.5 Natural Ventilation
Natural ventilation of an occupied space shall be through windows, doors, louvers or other openings to the outdoors. The operating mechanism for such openings shall be provided with ready access so that the openings are readily controllable by the building occupants.
1202.5.1 Ventilation Area Required
The openable area of the openings to the outdoors shall be not less than 4 percent of the floor area being ventilated.
1202.5.1.1 Adjoining Spaces
Where rooms and spaces without openings to the outdoors are ventilated through an adjoining room, the opening to the adjoining room shall be unobstructed and shall have an area of not less than 8 percent of the floor area of the interior room or space, but not less than 25 square feet (2.3 m 2 ). The openable area of the openings to the outdoors shall be based on the total floor area being ventilated.
Exception: Exterior openings required for ventilation shall be allowed to open into a sunroom with thermal isolation or a patio cover provided that the openable area between the sunroom addition or patio cover and the interior room shall have an area of not less than 8 percent of the floor area of the interior room or space, but not less than 20 square feet (1.86 m 2 ). The openable area of the openings to the outdoors shall be based on the total floor area being ventilated.
1202.5.1.2 Openings Below Grade
Where openings below grade provide required natural ventilation , the outside horizontal clear space measured perpendicular to the opening shall be one and one-half times the depth of the opening. The depth of the opening shall be measured from the average adjoining ground level to the bottom of the opening.
1202.5.2 Contaminants Exhausted
Contaminant sources in naturally ventilated spaces shall be removed in accordance with the International Mechanical Code and the International Fire Code.
1202.5.2.1 Bathrooms
Rooms containing bathtubs, showers, spas and similar bathing fixtures shall be mechanically ventilated in accordance with the International Mechanical Code.
1202.5.3 Openings on Yards or Courts
Where natural ventilation is to be provided by openings onto yards or courts , such yards or courts shall comply with Section 1205.
1202.6 Other Ventilation and Exhaust Systems
Ventilation and exhaust systems for occupancies and operations involving flammable or combustible hazards or other contaminant sources as covered in the International Mechanical Code or the International Fire Code shall be provided as required by both codes.
Section 1204 Lighting
1204.1 General
Every space intended for human occupancy shall be provided with natural light by means of exterior glazed openings in accordance with Section 1204.2 or shall be provided with artificial light in accordance with Section 1204.3. Exterior glazed openings shall open directly onto a public way or onto a yard or court in accordance with Section 1205.
1204.2 Natural Light
The minimum net glazed area shall be not less than 8 percent of the floor area of the room served.1204.2.1 Adjoining Spaces
For the purpose of natural lighting, any room is permitted to be considered as a portion of an adjoining room where one-half of the area of the common wall is open and unobstructed and provides an opening of not less than one-tenth of the floor area of the interior room or 25 square feet (2.32 m 2 ), whichever is greater.
Exception: Openings required for natural light shall be permitted to open into a sunroom with thermal isolation or a patio cover where the common wall provides a glazed area of not less than one-tenth of the floor area of the interior room or 20 square feet (1.86 m 2 ), whichever is greater.
1204.2.2 Exterior Openings
Exterior openings required by Section 1204.2 for natural light shall open directly onto a public way , yard or court , as set forth in Section 1205.
Exceptions:- Required exterior openings are permitted to open into a roofed porch where the porch meets all of the following criteria:
- Abuts a public way , yard or court .
- Has a ceiling height of not less than 7 feet (2134 mm).
- Has a longer side at least 65 percent open and unobstructed.
1204.3 Artificial Light
Artificial light shall be provided that is adequate to provide an average illumination of 10 footcandles (107 lux) over the area of the room at a height of 30 inches (762 mm) above the floor level.
1204.4 Stairway Illumination
Stairways within dwelling units and exterior stairways serving a dwelling unit shall have an illumination level on tread runs of not less than 1 footcandle (11 lux). Stairways in other occupancies shall be governed by Chapter 10.
1204.4.1 Controls
The control for activation of the required stairway lighting shall be in accordance with NFPA 70.1204.5 Emergency Egress Lighting
The means of egress shall be illuminated in accordance with Section 1008.1.Section 1205 Yards or Courts
1205.1 General
This section shall apply to yards and courts adjacent to exterior openings that provide natural light or ventilation. Such yards and courts shall be on the same lot as the building.
1205.2 Yards
Yards shall be not less than 3 feet (914 mm) in width for buildings two stories or less above grade plane. For buildings more than two stories above grade plane , the minimum width of the yard shall be increased at the rate of 1 foot (305 mm) for each additional story . For buildings exceeding 14 stories above grade plane , the required width of the yard shall be computed on the basis of 14 stories above grade plane .
1205.3 Courts
Courts shall be not less than 3 feet (914 mm) in width. Courts having windows opening on opposite sides shall be not less than 6 feet (1829 mm) in width. Courts shall be not less than 10 feet (3048 mm) in length unless bounded on one end by a public way or yard . For buildings more than two stories above grade plane , the court shall be increased 1 foot (305 mm) in width and 2 feet (610 mm) in length for each additional story . For buildings exceeding 14 stories above grade plane , the required dimensions shall be computed on the basis of 14 stories above grade plane .
1205.3.1 Court Access
Access shall be provided to the bottom of courts for cleaning purposes.1205.3.2 Air Intake
Courts more than two stories in height shall be provided with a horizontal air intake at the bottom not less than 10 square feet (0.93 m 2 ) in area and leading to the exterior of the building unless abutting a yard or public way .
1205.3.3 Court Drainage
The bottom of every court shall be properly graded and drained to a public sewer or other approved disposal system complying with the International Plumbing Code.
Section 1206 Sound Transmission
1206.1 Scope
This section shall apply to common interior walls, partitions and floor/ceiling assemblies between adjacent dwelling units and sleeping units or between dwelling units and sleeping units and adjacent public areas such as halls, corridors , stairways or service areas .
1206.2 Airborne Sound
Walls, partitions and floor-ceiling assemblies separating dwelling units and sleeping units from each other or from public or service areas shall have a sound transmission class of not less than 50, or not less than 45 if field tested, for airborne noise where tested in accordance with ASTM E90. Alternatively, the sound transmission class of walls, partitions and floor-ceiling assemblies shall be established by engineering analysis based on a comparison of walls, partitions and floor-ceiling assemblies having sound transmission class ratings as determined by the test procedures set forth in ASTM E90. Penetrations or openings in construction assemblies for piping; electrical devices; recessed cabinets; bathtubs; soffits; or heating, ventilating or exhaust ducts shall be sealed, lined, insulated or otherwise treated to maintain the required ratings. This requirement shall not apply to entrance doors; however, such doors shall be tight fitting to the frame and sill.
