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Buildings shall be provided with natural ventilation in accordance with Section 1203.4.or mechanical ventilation in accordance with Minnesota Rules, Chapter 1346. For additional ventilation requirements, see Minnesota Rules, Chapters 1322 and 1323, as applicable.
- Buildings or portions thereof that are not intended for normal human occupancy, or where the primary purpose is not associated with human comfort.
- Group U occupancies.
Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing members shall have cross ventilation for each separate space by ventilation openings protected against the entrance of rain and snow. Blocking and bridging shall be arranged so as not to interfere with the movement of air. An airspace of not less than 1 inch (25 mm) shall be provided between the insulation and the roof sheathing. The net free ventilating area shall not be less than 1/150th of the area of the space ventilated.
- The net free cross-ventilation area shall be permitted to be reduced to 1/300 provided that not less than 50 percent and not more than 80 percent of the required ventilating area provided by ventilators located in the upper portion of the space to be ventilated at least 3 feet (914 mm) above eave or cornice vents with the balance of the required ventilation provided by eave or cornice vents.
- The net free cross-ventilation area shall be permitted to be reduced to 1/300 where a Class I or II vapor barrier is installed on the warm-in-winter side of the ceiling.
- Attic ventilation shall not be required when determined not necessary by the building official due to atmospheric or climatic conditions.
Exterior openings into the attic space of any building intended for human occupancy shall be protected to prevent the entry of birds, squirrels, rodents, snakes and other similar creatures. Openings for ventilation having a least dimension of not less than 1/16 inch (1.6 mm) and not more than 1/4 inch (6.4 mm) shall be permitted. Openings for ventilation having a least dimension larger than 1/4 inch (6.4 mm) shall be provided with corrosion-resistant wire cloth screening, hardware cloth, perforated vinyl or similar material with openings having a least dimension of not less than 1/16 inch (1.6 mm) and not more than 1/4 inch (6.4 mm). Where combustion air is obtained from an attic area, it shall be in accordance with Chapter 7 of the International Mechanical Code.
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 openings through foundation walls or exterior walls. Such openings shall be placed so as to provide cross ventilation of the under-floor space.
The net area of ventilation openings shall not be less than 1 square foot for each 150 square feet (0.67 m2 for each 100 m2) of crawl-space area. 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 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).
The following are exceptions to Sections 1203.3.and 1203.3.1:
- Where warranted by climatic conditions, ventilation openings to the outdoors are not required if ventilation openings to the interior are provided.
- The total area of ventilation openings is permitted to be reduced to 1/1,500 of the under-floor area where the ground surface is covered with a Class I vapor retarder material and the required openings are placed so as to provide cross ventilation of the space. The installation of operable louvers shall not be prohibited.
- Ventilation openings are not required where continuously operated mechanical ventilation is provided at a rate of 1.0 cubic foot per minute (cfm) for each 50 square feet (1.02 L/s for each 10 m2) of crawl space floor area and the ground surface is covered with a Class I vapor retarder.
- Ventilation openings are not required where the ground surface is covered with a Class I vapor retarder, the perimeter walls are insulated and the space is conditioned in accordance with the International Energy Conservation Code.
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.
The openable area of the openings to the outdoors shall be not less than 4 percent of the floor area being ventilated.
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 m2). 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 permitted 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 m2). The openable area of the openings to the outdoors shall be based on the total floor area being ventilated.
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.
Contaminant sources in naturally ventilated spaces shall be removed in accordance with the International Mechanical Code and the International Fire Code.
Interior spaces intended for human occupancy shall be provided with active or passive space-heating systems capable of maintaining an indoor temperature of not less than 68°F (20°C) at a point 3 feet (914 mm) above the floor on the design heating day.
Exception: Space heating systems are not required for interior spaces where the primary purpose of the space is not associated with human comfort.
Every space intended for human occupancy shall be provided with natural light by means of exterior glazed openings in accordance with Section 1205.2.or shall be provided with artificial light in accordance with Section 1205.3. Exterior glazed openings shall open directly onto a public way or onto a yard or court in accordance with Section 1206.
The minimum net glazed area shall be not less than 8 percent of the floor area of the room served.
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 m2), whichever is greater.
Exterior openings required by Section 1205.2.for natural light shall open directly onto a public way, yard or court, as set forth in Section 1206.
- Required exterior openings are permitted to open into a roofed porch where the porch:
- Skylights are not required to open directly onto a public way, yard or court.
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.
The control for activation of the required stairway lighting shall be in accordance with NFPA 70.
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.
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.
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.
Walls, partitions and floor/ceiling assemblies separating dwelling units from each other or from public or service areas shall have a sound transmission class (STC) of not less than 50 (45 if field tested) for air-borne noise when tested in accordance with 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 dwelling unit entrance doors; however, such doors shall be tight fitting to the frame and sill.
Occupiable spaces, habitable spaces and corridors shall have a ceiling height of not less than 7 feet 6 inches (2286 mm). Bathrooms, toilet rooms, kitchens, storage rooms and laundry rooms shall be permitted to have a ceiling height of not less than 7 feet (2134 mm).
- In one- and two-family dwellings, beams or girders spaced not less than 4 feet (1219 mm) on center shall be permitted to project not more than 6 inches (152 mm) below the required ceiling height.
- If any room in a building has a sloped ceiling, the prescribed ceiling height for the room is required in one-half the area thereof. Any portion of the room measuring less than 5 feet (1524 mm) from the finished floor to the ceiling shall not be included in any computation of the minimum area thereof.
- The height of mezzanines and spaces below mezzanines shall be in accordance with Section 505.1.
Any room with a furred ceiling shall be required to have the minimum ceiling height in two-thirds of the area thereof, but in no case shall the height of the furred ceiling be less than 7 feet (2134 mm).
An efficiency living unit shall conform to the requirements of the code except as modified herein:
- The unit shall have a living room of not less than 220 square feet (20.4 m2) of floor area. An additional 100 square feet (9.3 m2) of floor area shall be provided for each occupant of such unit in excess of two.
- The unit shall be provided with a separate closet.
- The unit shall be provided with a kitchen sink, cooking appliance and refrigeration facilities, each having a clear working space of not less than 30 inches (762 mm) in front. Light and ventilation conforming to this code shall be provided.
- The unit shall be provided with a separate bathroom containing a water closet, lavatory and bathtub or shower.
Crawl spaces shall be provided with no fewer than one access opening which shall be not less than 18 inches by 24 inches (457 mm by 610 mm).
Access to mechanical equipment and appliances installed in underfloor areas, in attic spaces, and on roofs or elevated structures shall be in accordance with this section and the Minnesota Mechanical Code.
Where mechanical equipment or appliances requiring periodic inspection, service, or maintenance are installed on roofs or elevated structures, a permanent stair shall be provided for access.
Exception: A portable ladder may be used for dwellings, replacement equipment and appliances on existing buildings, and exterior roof access points not exceeding 16 feet (4.9 m) above grade, unless the building official determines that the unique shape of the roof does not allow safe access with a portable ladder.
The permanent stair shall, at a minimum, meet the following:
- The stair shall be installed at an angle of not more than 60 degrees measured from the horizontal plane;
- The stair shall have flat treads at least 6 inches (152 mm) deep and a clear width of at least 18 inches (457 mm) with equally spaced risers at least 10.5 inches (267 mm) high and not exceeding 14 inches (356 mm);
- The stair shall have intermediate landings not exceeding 18 feet (5.5 m) vertically;
- The stair shall be installed with continuous handrails on both sides of the stair;
- Interior stairs shall terminate at the underside of the roof at a hatch or scuttle of at least 8 square feet (0.74 m2) with a minimum dimension of 20 inches (508 mm);
- When a roof access hatch or scuttle is located within ten feet (3.0 m) of a roof edge, a guard shall be installed in accordance with this code.
- Exterior stairs shall terminate at the roof access point or at a level landing of at least 8 square feet (0.74 m2) with a minimum dimension of 20 inches (508 mm). The landing shall have a guard installed in accordance with IMC Section 304.9.
Where a change in roof elevation greater than 30 inches (762 mm) but not exceeding 16 feet (4.9 m) exists, a permanent ladder shall be provided. The ladder may be vertical. The ladder shall, at a minimum, meet the following:
- Width shall be at least 16 inches (406 mm).
- Rung spacing shall be a maximum of 14 inches (356 mm).
- Toe space shall be at least 6 inches (152 mm).
- Side railings shall extend at least 30 inches (762 mm) above the roof or parapet wall.
The number and type of plumbing fixtures provided in any occupancy shall comply with Chapter 29.
In other than dwelling units, toilet, bathing and shower, room floor finish material shall have a smooth, hard, nonabsorbent surface, such as portland cement, concrete, ceramic tile, sheet vinyl, or other approved floor covering material. The intersections of such floors with walls shall have a smooth, hard, nonabsorbent vertical base that extends upward onto the walls at least 4 inches (101 mm).
Walls and partitions within 2 feet (610 mm) of service sinks, urinals and water closets shall have a smooth, hard, nonabsorbent surface, to a height of not less than 4 feet (1219 mm) above the floor, and except for structural elements, the materials used in such walls shall be of a type that is not adversely affected by moisture.
Exception: This section does not apply to the following buildings and spaces:
- Dwelling units and sleeping units.
- Toilet rooms that are not accessible to the public and which have not more than one water closet.
Accessories such as grab bars, towel bars, paper dispensers and soap dishes, provided on or within walls, shall be installed and sealed to protect structural elements from moisture.
Shower compartments and walls above bathtubs with installed shower heads shall be finished with a smooth, nonabsorbent surface to a height not less than 70 inches (1778 mm) above the drain inlet.
Each water closet utilized by the public or employees shall occupy a separate compartment with walls or partitions and a door enclosing the fixtures to ensure privacy.
- Water closet compartments shall not be required in a single-occupant toilet room with a lockable door.
- Toilet rooms located in child day care facilities and containing two or more water closets shall be permitted to have one water closet without an enclosing compartment.
- This provision is not applicable to toilet areas located within Group I-3 occupancy housing areas.
Each urinal utilized by the public or employees shall occupy a separate area with walls or partitions to provide privacy. The walls or partitions shall begin at a height not more than 12 inches (305 mm) from and extend not less than 60 inches (1524 mm) above the finished floor surface. The walls or partitions shall extend from the wall surface at each side of the urinal not less than 18 inches (457 mm) or to a point not less than 6 inches (152 mm) beyond the outermost front lip of the urinal measured from the finished backwall surface, whichever is greater.