The following language shall be inserted as a new Section 309:
"309. RESIDENTIAL OCCUPANCIES
309.1 Increase in number of dwelling units or sleeping units.
Where the number of dwelling units or sleeping units within a fire area in a building containing an existing Group R occupancy is increased, the building shall comply with Section 309.1.1 or 309.1.2, as applicable. Any increase in the number of existing dwelling units or sleeping units shall also comply with the Chicago Zoning Ordinance.
309.1.1 One additional unit.
Where alterations will increase the number of existing dwelling units or sleeping units by no more than one, the newly-created unit shall not be required to comply with all requirements for new construction provided the following conditions are met:
1. The building shall not exceed the maximum number of stories above grade plane based on construction type in Table 309.1.1. Buildings of mixed construction shall be governed by the requirements of the least fire-resistive construction type.
2. Where the new unit is in a basement, the basement walls shall be impervious to leakage of underground and surface runoff water and shall be protected against dampness.
3. The dimensions of rooms in the new unit shall comply with Section 1207 of the Chicago Building Code.
4. The new unit shall be provided with natural light and natural ventilation as required by Sections 1202 and 1204 of the Chicago Building Code.
5. The new unit shall have at least the number of exits or exit access doorways required by Section 1006 of the Chicago Building Code. A second means of egress may pass through a room or space containing a heating plant.
6. The floor-ceiling assembly between the new unit and an existing unit shall have a fire-resistance rating of not less than 30 minutes or be original lath and plaster construction.
7. Walls between the new unit and an existing unit or between the new unit and a corridor or exit stairway shall have a fire-resistance rating of not less than 30 minutes or be original lath and plaster construction.
8. The unit shall be separated from incidental uses adjacent to the unit in accordance with Section 509.1 of the Chicago Building Code.
If the number of existing dwelling units or sleeping units in a building has previously been increased in accordance with this section or prior Sections 78.1-22 or 13-200-230 of the Municipal Code, the building and every additional dwelling unit or sleeping unit shall comply with Section 309.1.2.
TABLE 309.1.1
MAXIMUM NUMBER OF STORIES ABOVE GRADE PLANE
MAXIMUM NUMBER OF STORIES ABOVE GRADE PLANE
CONSTRUCTION TYPE | STORIES ABOVE GRADE PLANE |
CONSTRUCTION TYPE | STORIES ABOVE GRADE PLANE |
IA | UL |
IB | 11 a |
IIA, IIIA or IV | 4 a |
IIIB | 3 |
VA | 3 a |
VB | 2 |
IIB | 1 a |
a. One additional story is allowed in buildings equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 of the Chicago Building Code. | |
309.1.2 Two or more additional units.
Where alterations will increase the number of existing dwelling units or sleeping units by two or more, the newly-created units shall not be required to comply with all requirements for new construction provided the following conditions are met:
1. Conditions 1-8 in Section 309.1.1 shall be met.
2. Interior exit stairways shall be enclosed with assemblies having a fire-resistance rating of not less than 2 hours and opening protectives in accordance with the Chicago Building Code. Existing assemblies may be of combustible construction so long as the required rating is provided.
Exception: In existing buildings up to 3 stories above grade plane, exit stairways shall be enclosed with assemblies having a fire-resistance rating of not less than 1 hour and existing 1-3/4 inch (44 mm) thick solid-core wood doors with 1-3/4 inch (44 mm) rabbeted frames or opening protectives in accordance with the Chicago Building Code.
3. Assemblies separating existing units from corridors shall have a fire-resistance rating of not less than 30 minutes.
4. Assemblies separating the new units from existing units and corridors shall have a fire-resistance rating of not less than 1 hour.
5. Doors between corridors and new and existing dwelling units and sleeping units shall be existing 1-3/4 inch (44 mm) thick solid-core wood doors with 1-3/4 inch (44 mm) rabbeted frames, existing doors tested to establish a fire-resistance rating of not less than 20 minutes or new doors in accordance with the Chicago Building Code.
6. Doors to exit stairways and doors between corridors and new and existing dwelling units and sleeping units shall be self-closing.
7. Incidental uses shall be enclosed in accordance with Section 509.1 of the Chicago Building Code.
8. Basement ceiling construction shall comply with Section 605.4 of the Chicago Building Code.
309.2 Alteration for use as congregate living facilities.
Where an existing Group R occupancy, not previously used as congregate living facilities, is subject to alterations for use as congregate living facilities, the building shall be equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 or 903.3.1.2 of the Chicago Building Code.
Exception: Congregate living facilities with three or fewer sleeping units.
309.3 Openings for natural light and ventilation in pre-1958 buildings.
In Group R occupancies constructed before January 1, 1958, for openings in original exterior walls, the minimum dimension of yards and courts perpendicular to the openings shall be allowed to be 6 inches (152 mm) less than required by Section 1205 of the Chicago Building Code."
(Amend Coun. J. 2-19-20, p. 14473, Art. IV, § 6)