13-200-240 Increase of two or more dwelling units.

   In any residential building or building of mixed occupancy with one of the occupancies being residential, the number of dwelling units may be increased by more than one dwelling unit above the number of legally established dwelling units providing the building complies with all of the requirements listed in Section 13-200-230, and also the following additional requirements:

   (a)   Stairways shall be enclosed with walls of one hour construction in buildings not exceeding three stories in height. Stairways shall be enclosed with walls of two hour construction if the building exceeds three stories in height. Stairwell enclosures may be combustible or noncombustible construction as long as the required separation ratings are met.

   (b)   Stairwell doors shall be one and three-fourths inches solid-core wood with one and three-fourths inches rabbeted wood frames in buildings not exceeding three stories in height. Stairwell doors shall be Class B and frames in buildings exceeding three stories in height. All stair doors shall be self-closing.

   (c)   All existing dwelling and corridor separations shall be one-half-hour rated construction, combustible or noncombustible. All new dwelling and corridor separations shall be one hour rated construction, combustible, or noncombustible.

   (d)   Corridor doors to dwelling units shall be one and three-fourths inches solid core wood with one and three-fourths inches rabbeted wood frames. All corridor doors to dwelling units shall be self-closing.

   (e)   Heating plant enclosures shall comply with the requirements of Section 15-8-190.

   (f)   Basement ceilings shall comply with the requirements of Section 13-60-200.

(Prior code § 78.1-23; Amend Coun. J. 10-28-87, p. 5549)

13-200-250 Additions.

   An existing building or structure may be increased in height or area up to the limits imposed by Chapter 13-48.

   (a)   When the floor area is increased by not more than 25 percent of the original building, only the new construction need conform to all requirements of this Code for new construction. When the floor area is increased by more than 25 percent of the original building, the entire building shall conform to all requirements of this Code.

   (b)   Where a fire wall complying with Chapter 15-8 is provided which separates the addition from the existing building, only the new construction need conform to all requirements of this Code for new construction, regardless of the percentage increase in area created by the addition. Such an addition with the required fire wall separation, may also be considered a separate building if on a separate lot.

   (c)   No addition shall impose exiting loads which exceed the capacity of the existing building exits without provision of additional exits, in conformance with Section 13-200-330 through and including 13-200-360 of this chapter for the existing building or Chapter 13-160 for the addition.

   (d)   No addition shall impose structural loads, either vertical or horizontal, which would cause the existing building to be subjected to stresses exceeding those permitted by the new construction. Any increase in floor or roof loading shall be investigated to determine the adequacy of the existing floor system to support the increased loads. If the existing floor system is found to be inadequate, it shall be modified to support the increased loads.

(Prior code § 78.1-24; Amend Coun. J. 2-13-85, p. 13525)

13-200-260 Porches and decks.

   Existing porches and decks may be repaired or replaced in the same location with construction of the same type as that of the existing porch or deck.

   (1)   Existing porches not exceeding three stories in height may be extended up one story to the roof level regardless of their location with respect to the lot line or other buildings on the same lot, if in conformance with the zoning ordinance.

   (2)   Existing porches may be enclosed, regardless of their location with respect to the lot line or other buildings on the same lot, if construction requirements of Chapter 13-60 are met. If the existing porch is less than six feet from an interior lot line, the enclosure shall be a minimum of one hour rated construction, if in conformance with the zoning ordinance.

   (3)   Replacement porches shall be designed to meet all load criteria for new construction.

(Prior code § 78.1-25; Amend Coun. J. 10-1-03, p. 9163, § 4.12)

13-200-270 Dormers.

   Dormers may be added to any residential building provided that zoning requirements and the following requirements are met.

   (a)   If dormers are added to an attic space which is part of the apartment below it, the attic floor shall not be considered an additional floor in terms of building height if all of the following apply:

      (1)   The total and dormered area does not exceed two-thirds of the floor area of the same dwelling unit on the floor immediately below, when counting all areas with a headroom of five feet or higher;

      (2)   The dormer addition does not exceed the height of the existing building ridge line or the maximum building height permitted by Table 13-48-030, whichever is higher;

      (3)   The existing roof configuration has not been altered along the street lot line and the street- facing dormer wall is held back at least 24 inches from the face of the wall below;

      (4)   The number of living levels, as defined in Section 13-4-010, shall not exceed three levels in Type II-C, IV-A and IV-B buildings, or four floors in Type III-B buildings.

   (b)   Along interior lot lines, dormers may be built with their outer wall flush with the existing wall below, provided, however, such construction complies with the Zoning Ordinance.

   (c)   Dormers built on a building of ordinary construction (Type III-B or III-C) may be built of one hour metal stud or fire retardant treated wood in lieu of masonry, provided it meets the applicable construction requirements of Chapter 13-60 and does not exceed the height and area limitations of Chapter 13-48.

   (d)   Dormers built on a building of combustible frame construction (Type IV-A and IV-B) may be built of wood frame construction, provided it meets the applicable construction requirements of Chapter 13-60 and does not exceed the height and area limitations of Chapter 13-48.

(Prior code § 78.1-26; Amend Coun. J. 10-2-95, p. 8040)

13-200-280 Skylights.

   Prefabricated standard acrylic or polycarbonate skylight units may be installed in existing buildings not exceeding ten percent of the total roof area. In addition, custom built skylights may be installed in existing buildings if their frames are constructed of noncombustible material and if they are glazed with laminated glass or other approved safety glazing materials.

(Prior code § 78.1-27)

13-200-290 Utilization of existing space within residential buildings.

   Utilization and finishing of basement and attic space, including dormer additions, which make productive use of the existing floor area, and which become part of an existing dwelling unit but are not used to create additional units, shall not be considered as additional stories for purposes of height limitations under the code. However, the number of living levels, exclusive of the basement, is not to exceed three levels in Type IV-A and IV-B buildings, and four levels in Type III-B and III-C buildings.

(Prior code § 78.1-28)

13-200-300 Alterations and repairs.

   In alterations or repairs to an existing building, all new construction shall comply with the applicable provisions of this Code for new construction, except as follows:

   (a)   The department of buildings may approve minor nonstructural additions, alterations, or repairs using materials conforming to those with which the original building was constructed, providing they have the required strength and fire resistance.

   (b)   Officially designated historical buildings or structures shall meet the requirements of Section 13-200-100 “Historic preservation”.

   (c)   Buildings which will undergo a change of occupancy in conjunction with the alterations or repairs shall also meet the requirements of Sections 13-200-120 through and including 13-200-200 “Change of occupancy”.

   (d)   Residential buildings which will increase the number of legally established dwelling units shall also meet the requirements of the Sections 13-200-210 through and including 13-200-240 “Increase in number of dwelling units”.

   (e)   In buildings containing not more than three dwelling units, basement recreation rooms not used for sleeping purposes may comply with the following minimum requirements when smoke alarms complying with Sections 13-196-100 through and including 13-196-160 are provided in each dwelling unit in the building and in that portion of the basement used as a recreation room:

      (1)   Exterior walls of masonry or concrete construction may be furred with wood no larger than two inches by four inches. Paneling may be applied directly to this furring provided the paneling is not more combustible than wood.

      (2)   Partitions shall have a fire rating not less than one-half hour or may consist of wood studs covered one or both sides with paneling not more combustible than wood, provided the length of the interior partitioning shall not exceed the width of the basement plus ten feet.

      (3)   The ceiling finish in any basement recreation room shall have a flame-spread rating not to exceed Class I (0 to 25).

(Prior code § 78.1-29; Amend Coun. J. 10-28-87, p. 5549; Amend Coun. J. 9-13-89, p. 4604; Amend Coun. J. 6-14-95, p. 2841; Amend Coun. J. 3-5-03, p. 104990, § 40; Amend Coun. J. 11-13-07, p. 14999, Art. II, § 1; Amend Coun. J. 9-6-17, p. 55278, Art. VI, § 33)

13-200-310 Building over 80 feet in height.

   Any building over 80 feet in height which is altered or repaired, the cost of which in any consecutive 30 months exceeds 50 percent of the reproduction cost of the building, shall comply with requirements of Chapter 13-76 for high-rise buildings, and Chapter 15-8 for stair, elevator and shaft enclosures.

(Prior code § 78.1-30; Amend Coun. J. 12-15-04, p. 39962, § 1)

13-200-320 Assembly occupancy alterations.

   Any stage or projection block hereafter altered or remodeled shall comply in its entirety with the provisions of this Code for new construction:

   (a)   In assembly units having fixed seating, any alteration of the seating arrangement or of any means of exit shall comply with the provisions of Chapter 13-84, and any such alterations of seating shall comply with all the means of egress requirements of this Code.

   (b)   No alteration or extension of any existing system of heating or refrigeration or any system of piping or machinery in which hazardous gases or liquids are contained, or which are prohibited in an assembly unit under this Code, shall be made, unless all parts of such system and the rooms or spaces containing them shall be made to comply with the provisions of this Code.

   (c)   Any room in an assembly unit hereafter converted for any use requiring special protecting under this Code shall be made to comply with the provisions of this Code for such special protection.

   (d)   Areas used for storage of combustible containers in new and existing buildings with exhibition areas shall be enclosed with two-hour fire-resistive construction and shall be equipped with a standard sprinkler system, as defined in Chapter 15-16 of this Code.

   (e)   Fire alarm systems and other fire protection systems shall be provided, in accordance with requirements of Chapter 15-16.

   (f)   Exit lights shall be provided, in accordance with requirements of Section 13-160-700.

   (g)   Means of egress lighting shall be provided, in accordance with the requirements of Section 13-160-660.

   (h)   Emergency electrical systems and lighting shall be provided, in accordance with the requirements of Section 14E-7-700.

(Prior code § 78.1-31; Amend Coun. J. 6-14-95, p. 2841; Amend Coun. J. 11-9-16, p. 36266, § 27; Amend Coun. J. 9-6-17, p. 55278, Art. II, § 47)