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Record No: CB 119248    Version: Council Bill No: CB 119248
Type: Ordinance (Ord) Status: Passed
Current Controlling Legislative Body City Clerk
On agenda: 5/21/2018
Ordinance No: Ord 125588
Title: AN ORDINANCE amending the 2015 Seattle Building Code as adopted by Ordinance 125161; allowing the height limitation increase for Occupancy Group R-2 of Type IIIA construction be increased to six stories and 75 feet where all specified provisions are met.
Sponsors: Rob Johnson
Attachments: 1. Mayor's Letter on Returning Bill Unsigned 119248
Supporting documents: 1. Summary and Fiscal Note, 2. Presentation (05/16/18), 3. CB 119248 v2 Proposed Amendments (added 5/16/18), 4. Signed Ordinance 125588, 5. Affidavit of Publication

CITY OF SEATTLE

ORDINANCE __________________

COUNCIL BILL __________________

title

AN ORDINANCE amending the 2015 Seattle Building Code as adopted by Ordinance 125161; allowing the height limitation increase for Occupancy Group R-2 of Type IIIA construction be increased to six stories and 75 feet where all specified provisions are met.

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BE IT ORDAINED BY THE CITY OF SEATTLE AS FOLLOWS:

Section 1. Section 510 of the 2015 Seattle Building Code, enacted by Ordinance 125161, is amended as follows:

SECTION 510
SPECIAL PROVISIONS

510.1 General. The provisions in Sections 510.2 through 510.10 shall permit the use of special conditions that are exempt from, or modify, the specific requirements of this chapter regarding the allowable building heights and areas of buildings based on the occupancy classification and type of construction, provided the special condition complies with the provisions specified in this section for such condition and other applicable requirements of this code. The provisions of sections 510.2 through ((510.8)) 510.7 are to be considered independent and separate from each other.

Interpretation I510:  Sections 510.2 through ((510.8)) 510.7 are not permitted to be used in combination with each other. Sections 510.8 through 510.10 are permitted to be used in combination with Section 510.2.

510.2 Horizontal building separation allowance. A building shall be considered as separate and distinct buildings for the purpose of determining area limitations, continuity of fire walls, limitation of number of stories and type of construction where all of the following conditions are met:

1. The buildings are separated with a horizontal assembly having a fire-resistance rating of not less than 3 hours.

2. The building below and including the horizontal assembly is of Type IA construction.

3. Shaft, stairway, ramp and escalator enclosures through the horizontal assembly shall have not less than a 2-hour fire-resistance rating with opening protectives in accordance with Section 716.5.

Exception: Where the enclosure walls below the horizontal assembly have not less than a 3-hour fire-resistance rating with opening protectives in accordance with Section 716.5, the enclosure walls extending above the horizontal assembly shall be permitted to have a 1-hour fire-resistance rating, provided:

1. The building above the horizontal assembly is not required to be of Type I construction;

2. The enclosure connects fewer than four stories; and

3. The enclosure opening protectives above the horizontal assembly have a fire protection rating of not less than 1 hour.

4.                      Stairways permitted to be constructed of wood above the horizontal assembly are also permitted to be constructed of wood below the horizontal assembly.  See Section 202 for the definition of stairway.

5. The building or buildings above the horizontal assembly shall be permitted to have any of the following occupancies:

5.1. Multiple Group A occupancy uses, each with an occupant load of less 300;

5.2. Group B;

5.3. Group I-1, Condition 2 licensed care facilities;

5.4. Group M;

5.5. Group R;

5.6. Group S-2 parking garage used for the parking and storage of private motor vehicles; and

5.7. Uses incidental to the operation or serving occupants of the building (including entry lobbies, mechanical rooms, storage areas and similar uses).

6. The building below the horizontal assembly is permitted to be any occupancy allowed by this code except Group H.

7. The maximum building height in feet (mm) shall not exceed the limits set forth in Section 504.3 for the building having the smaller allowable height as measured from the grade plane.

8. All portions of the buildings above and below the three-hour horizontal assembly shall be protected throughout with an automatic sprinkler system that complies with Section 903.3.1.1.

9. Occupied floors shall be not more than 75 feet above the lowest level of fire department vehicle access.

Interpretation ((I509.2)) I510.2: For the purpose of this item, occupied roof decks are considered floors used for human occupancy if the occupant load of the deck is 10 or more on the roof of a building not equipped with an automatic sprinkler system or where the occupant load is 50 or more on the roof of a building that is equipped with an automatic sprinkler system.

10. Where the structure above the horizontal assembly is of Type V construction, and the structure or any portion of the structure is 7 stories above grade plane in height, all interior exit stairways shall be pressurized in accordance with Section 909.20 for low-rise stairways.

11. Where the structure above the horizontal assembly is not of Type V construction, interior exit stairways that connect more than 6 stories above the level of exit discharge for the stairway shall be pressurized in accordance with Section 909.20 for low-rise stairways.

* * *

((510.5)) 510.9 Group R-1 and R-2 buildings of Type IIIA construction. The height limitation for buildings of Type IIIA construction in Groups R-1 and R-2 shall be increased to six stories and 75 feet (22 860 mm) where the first-floor assembly above the basement has a fire-resistance rating of not less than 3 hours and the floor area is subdivided by 2-hour fire-resistance-rated fire walls into areas of not more than 3,000 square feet (279 m2).

((510.6)) 510.5 Group R-1 and R-2 buildings of Type IIA construction. The height limitation for buildings of Type IIA construction in Groups R-1 and R-2 shall be increased to nine stories and 100 feet (30 480 mm) where the building is separated by not less than 50 feet (15 240 mm) from any other building on the lot and from lot lines, the exits are segregated in an area enclosed by a 2-hour fire-resistance-rated fire wall and the first floor assembly has a fire-resistance rating of not less than 1 ½ hours.

((510.7)) 510.6 Open parking garage beneath Groups A, I, B, M and R. Open parking garages constructed under Groups A, I, B, M and R shall not exceed the height and area limitations permitted under Section 406.5. The height and area of the portion of the building above the open parking garage shall not exceed the limitations in Section 503 for the upper occupancy. The height, in both feet and stories, of the portion of the building above the open parking garage shall be measured from grade plane and shall include both the open parking garage and the portion of the building above the parking garage.

((510.7.1)) 510.6.1 Fire separation. Fire barriers constructed in accordance with Section 707 or horizontal assemblies constructed in accordance with Section 711 between the parking occupancy and the upper occupancy shall correspond to the required fire-resistance rating prescribed in Table 508.4 for the uses involved. The type of construction shall apply to each occupancy individually, except that structural members, including main bracing within the open parking structure, which is necessary to support the upper occupancy, shall be protected with the more restrictive fire-resistance-rated assemblies of the groups involved as shown in Table 601. Means of egress for the upper occupancy shall conform to Chapter 10 and shall be separated from the parking occupancy by fire barriers having not less than a 2-hour fire-resistance rating as required by Section 707 with self-closing doors complying with Section 716 or horizontal assemblies having not less than a 2-hour fire-resistance rating as required by Section 711, with self-closing doors complying with Section 716. Means of egress from the open parking garage shall comply with Section 406.5.

((510.8)) 510.7 Group B or M buildings with Group S-2 open parking garage above. Group B or M occupancies located below a Group S-2 open parking garage of a lesser type of construction shall be considered as a separate and distinct building from the Group S-2 open parking garage for the purpose of determining the type of construction where all of the following conditions are met:

1. The buildings are separated with a horizontal assembly having a fire-resistance rating of not less than 2 hours.

2. The occupancies in the building below the horizontal assembly are limited to Groups B and M.

3. The occupancy above the horizontal assembly is limited to a Group S-2 open parking garage.

4. The building below the horizontal assembly is of Type IA construction.

Exception: The building below the horizontal assembly shall be permitted to be of Type IB or II construction, but not less than the type of construction required for the Group S-2 open parking garage above, where the building below is not greater than one story in height above grade plane.

5. The height and area of the building below the horizontal assembly does not exceed the limits set forth in Section 503.

6. The height and area of the Group S-2 open parking garage does not exceed the limits set forth in Section 406.5. The height, in both feet and stories, of the Group S-2 open parking garage shall be measured from grade plane and shall include the building below the horizontal assembly.

7. Exits serving the Group S-2 open parking garage discharge directly to a street or public way and are separated from the building below the horizontal assembly by 2-hour fire barriers constructed in accordance with Section 707 or 2-hour horizontal assemblies constructed in accordance with Section 711, or both.

((510.9)) 510.8 Multiple buildings above a horizontal assembly. Where two or more buildings are provided above the horizontal assembly separating a Group S-2 parking garage or building below from the buildings above in accordance with the special provisions in Section 510.2, 510.3 or ((510.8)) 510.7, the buildings above the horizontal assembly shall be regarded as separate and distinct buildings from each other and shall comply with all other provisions of this code as applicable to each separate and distinct building.

510.10 Group R-2 buildings of Type IIIA construction. The height limitation for buildings of Type IIIA construction in Group R-2 shall be increased to six stories and 75 feet (22 860 mm) where all of the following conditions are met:

1. The first story of Type IIIA construction is separated from stories above with a horizontal assembly having a fire-resistance rating of not less than 2 hours.

2. All stories of Type IIIA construction greater than 6,000 gross square feet shall be subdivided into compartments, by 2-hour fire-resistance rated fire walls, with areas of not more than 12,000 gross square feet.

3. Each compartment shall have an enclosed exit access stairway, and a standpipe system in accordance with Section 905.

4. Unprotected vertical openings, including unenclosed exit access stairways, shall not penetrate floor/ceiling assemblies between stories of Type IIIA construction or between stories of Type IIIA and Type IA construction.

5. Mezzanines shall not be allowed in any story of the Type IIIA construction.

6. The maximum total design dead load shall be 50psf for all roof areas above the sixth story of Type IIIA construction.

Note: The dead load shall be calculated as specified in Chapter 2 and Section 1607.12.3.1.

 

Note: The maximum total design dead load of 50psf is permitted to be applied over the entire roof area above the sixth story of Type IIIA construction.

Section 2. This ordinance shall take effect and be in force 30 days after its approval by the Mayor, but if not approved and returned by the Mayor within ten days after presentation, it shall take effect as provided by Seattle Municipal Code Section 1.04.020.

Passed by the City Council the ________ day of _________________________, 2018, and signed by me in open session in authentication of its passage this _____ day of _________________________, 2018.

____________________________________

President ____________ of the City Council

Approved by me this ________ day of _________________________, 2018.

____________________________________

Jenny A. Durkan, Mayor

Filed by me this ________ day of _________________________, 2018.

____________________________________

Monica Martinez Simmons, City Clerk

(Seal)