This section contains portions of the 1994 Uniform Building Code which relate to basic minimum design requirements for residences (Group R occupancies, Division 3).
Excerpts from the 1994 Uniform Building Code , copyright ©
1994, are included in this guide with the permission of the publisher, the
International Conference of Building Officials.
Exits and Emergency Escapes
Sec. 310.4. Access and Exit Facilities and Emergency Escapes. Exits shall be provided as specified in Chapter 10.
Basements in dwelling units and every sleeping room below the fourth story shall have at least one operable window or door approved for emergency escape or rescue which shall open directly into a public street, public alley, yard or exit court. The emergency door or window shall be operable from the inside to provide a full, clear opening without the use of separate tools.
Escape or rescue windows shall have a minimum net clear openable area of 5.7 square feet (0.53 square meters). The minimum net clear openable height dimension shall be 24 inches (610 mm). The minimum net clear openable width dimension shall be 20 inches (508 mm). When windows are provided as a means of escape or rescue, they shall have a finished sill height not more than 44 inches (1118 mm) above the floor.
Escape and rescue windows with a finished sill height below the adjacent ground elevation shall have a window well. Window wells at escape windows shall comply with the following:
Bars, grilles, grates or similar devices may be installed on an emergency escape or rescue windows or doors, provided:
Light, Ventilation and Sanitation
Sec. 310.5. Light, Ventilation and Sanitation. Light and ventilation shall be specified in Chapter 12. The number of plumbing fixtures shall not be less than specified in Section 2902.6.
Sec. 1203. Light and Ventilation in Group R Occupancies.
1203.1 General. For the purpose of determining the light or ventilation for Group R Occupancies required by this section, any room may be considered as a portion of an adjoining room when 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 (2.3 square meters), whichever is greater.
Exterior openings for natural light or ventilation required by this section shall open directly onto a public way or a yard or court as set forth in Section 1203.4.
|EXCEPTIONS:||1. Required exterior openings may open into a roofed porch where the porch:|
|1.1. Abuts a public way, yard or court; and|
|1.2. Has a ceiling height of not less than 7 feet (2134 mm); and|
|1.3. Has the longer side at least 65 percent open and unobstructed.|
Sec. 1203.2. Light. Guest rooms and habitable rooms within a dwelling unit shall be provided with natural light by means of exterior glazed openings with an area not less than one tenth of the floor area of such rooms with a minimum of 10 square feet (0.93 square meters).
EXCEPTION: Kitchens in Group R Occupancies may be provided with artificial light.
Sec. 1203.3. Ventilation. Habitable rooms within a dwelling unit shall be provided with natural ventilation by means of openable exterior openings with an area of not less than one twentieth of the floor area of such rooms with a minimum of 5 square feet (0.46 square meters).
In lieu of required exterior openings for natural ventilation, a mechanical ventilating system may be provided. Such system shall be capable of providing two air changes per hour in habitable rooms with a minimum of 15 cubic feet per minute (7 liters per second) of outside air per occupant during such time as the building is occupied.
Bathrooms, water closet compartments, laundry rooms and similar rooms shall be provided with natural ventilation by means of openable exterior openings with an area not less than one twentieth of the floor area of such rooms with a minimum of 1 1/2 square feet (0.14 square meters).
In lieu of required exterior openings for natural ventilation in bathrooms containing a bathtub or shower or combination thereof, laundry rooms, and similar rooms, a mechanical ventilation system connected directly to the outside capable of providing five air changes per hour shall be provided. Such systems shall be directly connected to the outside, and the point of discharge shall be at least 3 feet (914 mm) from any opening which allows air entry into occupied portions of the building. Bathrooms which contain only a water closet or lavatory or combination thereof, and similar rooms may be ventilated with an approved mechanical recirculating fan or similar device designed to remove odors from the air.
Sec. 1203.4. Yards and Courts.
Sec. 1203.4.1. General. This section shall apply to yards and courts adjacent to exterior openings that provide required natural light or ventilation. Such yards and courts shall be on the same property as the building.
Sec. 1203.4.2. Yards. Yards shall not be less than 3 feet (914 mm) in width for one-story and two-story buildings. For buildings more than two stories in height, the minimum width of the yard shall be increased at the rate of 1 foot (305 mm) for each additional story.
Sec. 1203.4.3. Courts. Courts shall not be less than 3 feet (914 mm) in width. Courts having windows opening on opposite sides shall not be less than 6 feet (1829 mm) in width. Courts bounded on three or more sides by the walls of the building shall not be 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 in height, the court shall be increased 1 foot (305 mm) in width and 2 feet (610 mm) in length for each additional story.
Adequate access shall be provided to the bottom of all courts for cleaning purposes. Every court 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 square meters) in area and leading to the exterior of the building unless abutting a yard or public way. The construction of the air intake shall be as required for the court walls of the building, but in no case shall be less than one-hour fire resistive.
Sec. 2902.6. Group R Occupancies. Buildings classified as Group R Occupancies shall be provided with at least one water closet.
Dwelling units shall be provided with a kitchen equipped with a kitchen sink. Dwelling units shall be provided with a bathroom equipped with facilities consisting of a water closet, lavatory and either a bathtub or a shower. Each sink, lavatory and either a bathtub or shower shall be equipped with hot and cold running water necessary for its normal operation.
Sec. 2904. Access to water closet stool. The water closet stool shall be located in clear space not less than 30 inches in width. The clear space in front of the water closet stool shall not be less than 24 inches.
Sec. 310.6. Room Dimensions.
Sec. 310.6.1. Ceiling Heights. Habitable space shall have a ceiling height of not less than 7 feet 6 inches (2286 mm) except as otherwise permitted in this section. Kitchens, halls, bathrooms and toilet compartments may have a ceiling height of not less than 7 feet (2134 mm) measured to the lowest projection of the ceiling. Where exposed beam ceiling members are spaced at less than 48 inches (1219 mm) on center, ceiling height shall be measured to the bottom of these members. Where exposed beam ceiling members are spaced at 48 inches (1219 mm) or more on center, ceiling height shall be measured to the bottom of the deck supported by these members, provided that the bottom of the members is not less than 7 feet (2134 mm) above the floor.
If any room in a building has a sloping ceiling, the prescribed ceiling height for the room is required in only one half the area thereof. No portion of the room measuring less than 5 feet (1524 mm) from the finished floor to the finished ceiling can be included in any computation of the minimum area thereof.
If a room has a furred ceiling, the prescribed ceiling height is required in two thirds the area thereof, but in no case shall the height of the furred ceiling be less than 7 feet (2134 mm).
Sec. 310.6.2. Floor Area. Dwelling units shall have at least one room which shall have not less than 120 square feet (11.2 square meters) of floor area. Other habitable rooms except kitchens shall have an area not less than 70 square feet (6.5 square meters). Efficiency dwelling units shall comply with the requirements of Section 310.7.
Sec. 310.6.3. Width. Habitable rooms other than a kitchen shall not be less than 7 feet (2134 mm) in any dimension.
Sec. 310.9. Smoke Detectors and Sprinkler Systems.
Sec. 310.9.1.1 General. Dwelling units that are used for sleeping purposes shall be provided with smoke detectors. Detectors shall be installed in accordance with the approved manufacturer's instructions.
Sec. 310.9.1.2. Additions, alterations or repairs to Group R Occupancies. When the valuation of an addition, alteration or repair to a Group R Occupancy exceeds $1000.00 and a permit is required, or when one or more sleeping rooms are added or created in existing Group R Occupancies, smoke detectors shall be installed in accordance with Subsections 3, 4 and 5 of this section.
|EXCEPTION:||Repairs to the exterior surfaces (such as reroofing) are exempt from this requirements of this section.|
Sec. 310.9.1.3. Power source. In new construction, required smoke detectors shall receive their primary power from the building wiring when such wiring is served from a commercial source and shall be equiped with a battery backup. The detector shall emit a signal when the batteries are low. Wiring shall be permanent and without a disconnecting switch other than those required for overcurrent protection. Smoke detectors may be solely battery operated when installed in existing buildings; or in buildings without commercial power; or in buildings which undergo alterations, repairs or additions regulated by Section 310.9.1.2.
Sec. 310.9.1.4. Location within dwelling units. In dwelling units, a detector shall be installed in each sleeping room and at a point centrally located in the corridor or area giving access to each separate sleeping area. When the dwelling unit has more than one story and in dwellings with basements, a detector shall be installed on each story and in the basement. In dwelling units where a story or basement is split into two or more levels, the smoke detector shall be installed on the upper level, except that when the lower level contains a sleeping area, a detector shall be installed on each level. When sleeping rooms are on an upper level, the detector shall be placed at the ceiling of the upper level in close proximity to the stairway. In dwelling units where the ceiling height of a room open to the hallway serving the bedrooms exceeds that of the hallway by 24 inches or more, smoke detectors shall be installed in the hallway and in the adjacent room. Detectors shall sound an alarm audible in all sleeping areas of the dwelling unit in which they are located.
Sec. 310.9.2. Sprinkler and standpipe systems. When required by Section 904.2.1 or other provisions of this Code, automatic sprinkler systems and standpipes shall be designed and installed as specified in Chapter 9.
Residential fire sprinkler systems are required for all residences west of Interstate 280.
Sec. 310.11. Heating. Dwelling units shall be provided with heating facilities capable of maintaining a room temperature of 70 degrees Farenheit (21 degree Celcius) at a point 3 feet (914 mm) above the floor in all habitable rooms.
Sec. 302.4. Fire Ratings for Occupancy Separations. Occupancy separations shall be provided between the various groups and divisions of occupancies as set forth in Table 3-B.
[EXCEPTION related to residential construction...]
3. In the one-hour occupancy separation between Group R, Division 3 and Group U Occupancies, the separation may be limited to the installation of materials approved for one-hour fire-resistive construction on the garage side and a self-closing, tight-fitting solid wood door 1 3/8 inches (35 mm) in thickness, OR a self-closing, tight-fitting door having a fire protection rating of not less than 20 minutes when tested in accordance with Part II of U.B.C. Standard 7-2, which is part of this code, is permitted in lieu of a one-hour fire assembly. Fire dampers need not be installed in air ducts passing through the wall, floor or ceiling separating a Group R, Division 3 Occupancy from a Group U Occupancy, provided such ducts within the Group U Occupancy are constructed of steel having a thickness not less than 0.019 inches (0.48 mm)(No. 26 galvanized sheet gage) and having no openings into the Group U Occupancy.
For your reference, an example of a one-hour, fire separation wall using wood studs, from Chapter 7, Table 7-B...
Item Number 17-1.3 - This wall must be a minimum of 2 x 4 (51 mm by 102 mm) wood studs 24 inches (610 mm) on center with 5/8 inch (15.9 mm) Type "X" gypsum wallboard, applied vertically or horizontally, nailed with 6d cooler or wallboard nails at 7 inches (178 mm) on center with end joints on nailing members. Stagger joints each side. Total thickness equal to 4 3/4 inches.
[Sec. 302.1 EXCEPTION related to residential carports...]
3. An occupancy separation need not be provided between a Group R, Division 3 Occupancy and a carport having no enclosed uses above, provided the carport is entirely open on two or more sides.
Stairways And Landings
Sec. 1006. Stairways.
Sec. 1006.1 General. Every stairway having two or more risers serving a building or portion thereof shall conform to the requirements of this section.
Sec. 1006.2 Width. Stairways serving an occupant load of 49 or less (residential construction - Ed.) shall not be less than 36 inches (914 mm) in width.
Handrails may project into the required width a distance of 3 1/2 inches (89 mm) from each side of a stairway. Stringers and other projections such as trim and similar decorative features may project into the required with 1 1/2 inches (38 mm) on each side.
Sec. 1006.3. Rise and Run. The rise of steps shall not be less than 4 inches (102 mm) or greater than 7 inches (178 mm). Except as permitted in Section 1006.4 and 1006.6, the run shall not be less than 11 inches (279 mm) as measured horizontally between the vertical planes of the furthermost projection of adjacent treads. Except as permitted in Sections 1006.4, 1006.5 and 1006.6, the largest tread run within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).
|EXCEPTIONS:||1. Private steps and stairways serving an occupant load of less than 10 and stairways to unoccupied roofs may be constructed with an 8-inch-maximum (203 mm) rise and a 9-inch-minimum (229 mm) run.|
|2. Where the bottom or top riser adjoins a sloping public way, walk or driveway having an established grade and serving as a landing, the bottom or top riser may be reduced along the slope to less than 4 inches (102 mm) in height with the variation in height of the bottom or top riser not to exceed 3 inches (76 mm) in every 3 feet (914 mm) of stairway width.|
Sec. 1006.4. Winding Stairways. In Group R, Division 3 Occupancies, winders may be used if the required width of run is provided at a point not more than 12 inches (305 mm) from the side of the stairway where the treads are narrower, but in no case shall any width of run be less than 6 inches (152 mm) at any point.
Sec. 1006.5. Circular Stairways. Circular stairways may be used as an exit, provided the minimum width of run is not less than 10 inches (254 mm) and the smaller radius is not less than twice the width of the stairway. The largest tread width or riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm).
Sec. 1006.6. Spiral Stairways. In Group R, Divisions 3 Occupancies, spiral stairways may be installed. Such stairways may be used for required exits when the area served is limited to 400 square feet (37.16 square meters).
The tread must provide a clear walking area measuring at least 26 inches (660 mm) from the outer edge of the supporting column to the inner edge of the handrail. A run of at least 7 1/2 inches (191 mm) is to be provided at a point 12 inches (305 mm) from where the tread is the narrowest. The rise must be sufficient to provide 6-foot 6-inch (1981 mm) headroom. The rise shall not exceed 9 1/2 inches (241 mm).
Sec. 1006.7. Landings. Every landing shall have a dimension measured in the direction of travel not less than the width of the stairway. Such dimension need not exceed 44 inches (1118 mm) when the stair has a straight run. There shall not be more than 12 feet (3658 mm) vertically between landings. For landings with adjoining doors, see Section 1004.10.
EXCEPTION: Stairs serving an unoccupied roof are exempt from these provisions.
Sec. 1006.8. Basement Stairways. When a basement stairway and a stairway to an upper story terminate at the same exit enclosure, an approved barrier shall be provided to prevent persons from continuing on into the basement. Directional exit signs shall be provided as specified in Section 1013. Exit Signs.
Sec. 1006.9. Handrails.
|EXCEPTIONS:||1. Stairways less than 44 inches (1118 mm) in width or stairways serving one individual dwelling unit in Group R, Division 3 Occupancies may have one handrail.|
|2. Private stairways 30 inches (762 mm) or less in height may have handrails on one side only.|
|3. Stairways having less than four risers and serving one individual dwelling unit in Group R, Division 3 or serving Group U Occupancies need not have handrails.|
The tops of handrails and handrail extensions shall be placed not less than 34 inches (864 mm) or more than 38 inches (965 mm) above the nosing of treads and landings. Handrails shall be continuous for the full length of the stairs and, except for private stairways, at least one handrail shall extend in the direction of the stair run not less than 12 inches (305 mm) beyond the top riser nor less than 12 inches (305 mm) beyond the bottom riser. Ends shall be returned or shall terminate in newel posts or safety terminals.
The handgrip portion of handrails shall not be less than 1 1/4 (32 mm) inches nor more than 2 inches (51 mm) in cross-sectional dimension or the shape shall provide an equivalent gripping surface. The handgrip portion of handrails shall have a smooth surface with no sharp corners.
Handrails projecting from a wall shall have a space of not less than 1 1/2 inches (38 mm) between the wall and the handrail.
Sec. 1006.10. Guardrails. Stairways open on one or both sides shall have guardrails as required by Section 1001.5.
Detached Garages And Accessory Buildings
Fire Resistant Materials And Construction
1994 UBC Chapters 5, 6 and 7, PAMC 18.88.090
Any structure less than 3 feet from a property line must have a one hour fire wall along that side and no openings (windows, doors, etc.) are permitted in this wall. An open sided carport or trellis must therefore be a minimum of 3 feet from a property line to the face of its supports. One hour construction in this situation means 5/8 inch type "X" gypsum wallboard attached to the interior and exterior side of the wall studs with exterior weather protection applied over the gypsum board.
Detached structures must be a minimum of 6 feet from any other structure. This distance is measured from face of support to face of support. Roof overhangs are permitted to extend into a yard at the rate of 2 inches of overhang per foot of yard distance between structures or property lines.