OSSC Table 503

Table 503 states that A-3 occupancies (roof deck) in Type IIlA construction may not be located higher than 3-stories above grade plane level. (Increases to four stories above grade plane with automatic sprinkler system increase-Section 504.2).

The proposed design (see attached Exhibit 1-1: Roof Deck Code AnalysisPian) calls for a 5,202 square foot roof deck to occur on the 6th Floor of this building. This deck is for the use of the apartment residents and includes an open seating area (including a natural gas fire pit-see related Appeal), a wood trellis defining a small outdoor kitchenette, a garden area, and a small fenced-off pet area. The open area that constitutes the majority of the "A" occupancy (south of egress path) is 2,455 square feet in area for a total area defined as A-3 of 4,101 gross square feet.

The roof deck has an occupant load of 274 people (see updated figures on Exhibit 1-1), is served by (2) means of egress with, for it's entire length, a well-defined illuminated egress path to (2) two-hour rated stairways (with emergency back up lighting for the path of egress across the length of the roof). As these two stairways descend in the building and penetrate the 3 hour rated occupancy separation at the 2nd floor level, the enclosures become 3 hour rated, thus increasing the degree of protection for those exiting the building. In addition, the building is fully-sprinklered (increasing, as noted above, the number of stories above grade from 3 to 4).

In the event of a fire, the roof deck can be served via fire apparatus from both Cook Street, a fire­ apparatus access road (and a 60'-0" yard adjacent to this side of the roof deck )-see Exhibit 1-2 Site Plan. See also Exhibit 1-3: Building Section at Roof Deck indicating actual vertical distance of roof deck above grade plane.

The roof deck construction assembly has a one-hour fire rating and is provided with a non-combustible synthetic wood decking at the walking surface.

Aside from serving as an essential and valuable amenity to the apartment complex, this alternate is required to provide a secure south-facing outdoor space that sits high enough in the building to allow for sunlight to access it when the property across Cook Street to the south is developed (Zoning allows a 100'-0" high building). The location of the roof deck on the 6th floor was also determined by the necessity to stack units below it and by Land Use Review considerations with regards to "stepping down" the facade to the existing residential neighborhood across Cook Street.

By Code, a roof deck is not considered to be a story. Table 503 identifies "Height limitations shown as stories and feet above grade plane". As a deck surface open to the sky, it therefore seems that the primary issue that we are addressing here is providing for the life safety of the 274 occupants using the roof deck that just happens to occur two floors above the Fourth Floor. We believe that we have made equivalent or greater accommodation in the Proposed Design for this alternate which can be summarized as follows:

1. The roof deck has a very clear exiting system to evacuate 274 occupants from the roof deck in the event of a fire. This includes providing an egress path across the deck surface that in the event of a loss of power will have a back-up source of illumination at the walking surface.
2. The roof deck abuts a 60'-0" yard to the south at it's Cook Street side and is accessible for it's

entire length on both that side and the north side (at the surface parking lot) to fire apparatus.

1. The roof deck is constructed with a 1 hour rated roof/ ceiling assembly that complies with

Type lII-A construction requirements of the Code.

1. The roof structure has been designed to accommodate the live load requirements of an assembly occupancy use.
2. The deck is fully accessible from both wings of the 6th floor and is in the accessible path that originates at the street level below and up through the elevators to the roof deck. The roof deck is fully compliant with current OSSC and ANSI code requirements.

2010 OSSC Table 601& Section 602.3 Type Ill

Table 601 requires 2 hour rated exterior bearing walls for Type lII-A construction.
Section 602.3 Type Ill states: " ...Fire-retardant-treated wood framing complying with Section 2303.2 shall be permitted within exterior wall assemblies of a 2-hour rating or less.

In compliance with the Bureau of Development Services' Paul Scarlett's May 13, 2013 directive (attached), buildings of Type 111-A construction may be of non-fire-retardant wood framing with the following conditions:

1. A. Exterior bearing walls less than 10' from property line shall be protected on the inside with two layers of 5/8" fire-rated gypsum board and one 5/8" layer of fire-rated gypsum sheathing over one 5/8" layer of fire-retardant-treated plywood. This comprises a 2 hour rated wall assembly (see attached Exhibit 2-2). In addition, from Applicant's Preliminary Fire Life Safety Meeting with Charles Auch, Fire Marshal representative Gary Boyles and Plans Examiner Jerry Englehardt on July 29, 2013, it was stated that all openings in these two hour rated exterior bearing walls would need to have 7" minimum solid wood blocking at all head, jamb and sill conditions. Likewise solid blocking for the full depth of the roof or floor member needs to occur at all locations where floor or roof structure meets these exterior bearing walls.

As part of this application, we would like to obtain approval for using the attached 19/32" thick
LP FlameBiock Fire-Rated OSB sheathing in lieu of 5/8" nominal fire-retardant plywood. Page
6 of the attached submittal identifies UL Listing and applicability for Type Ill Exterior walls.

Due to yards in excess of 30' on all other sides (including the West and East Interior Courtyard walls which have in excess of a 30' yard in front of them formed by an imaginary property line running down the center of the Interior Courtyard) , this condition applies only to the north wall of the Cook Street portion of the building between Gridlines "D" and "J" along Gridline "6.8". (See attached Exhibit 2-1: Code Analysis Plan for extent of 2 hour and 1 hour rated walls).

B. Exterior bearing walls equal to or greater than 10' from the property line shall be protected on the inside with two layers of 5/8" fire-rated gypsum board and protected on the outside with one layer of 5/8" nominal fire-rated gypsum sheathing over combustible wall sheathing. This comprises a 1 hour rated wall assembly (see attached Exhibit 2-3). In addition, from Applicant's Preliminary Fire Life Safety Meeting (noted above), it was determined that all openings in these one hour rated exterior bearing walls would need to have 3-1/2" minimum solid wood blocking at all head, jamb and sill conditions. Likewise solid blocking for the full depth of the roof or floor member needs to occur at all locations where floor or roof. structure meets these exterior bearing walls.

As part of this application, we would like to obtain approval for using the attached 19/32" thick LP FlameBiock Fire-Rated OSB sheathing in lieu of 5/8" nominal fire-rated gypsum sheathing. Page 6 of the attached submittal identifies UL Listing and applicability for Type Ill Exterior walls.

Due to yards in excess of 30' on all sides (including the West and East Interior Courtyard walls which have in excess of a 30' yard in front of them formed by an imaginary property line running down the center of the Interior Courtyard) , this condition applies to all exterior sides other than the wall plane identified above along Gridline "6.8". (See attached Exhibit 2-1: Code Analysis Plan for extent of 2 hour and 1 hour rated walls).

1. Exterior non-bearing walls shall be protected on the inside and outside with at least one layer of fire-rated gypsum board or gypsum sheathing, nominal 5/8" thickness, over combustible wall framing. This project: complies.
2. All exterior wall coverings shall be of non-combustible materials: This project has only two exterior wall coverings-both non-combustible-20 ga metal siding and Nichiha fiber cement panels (see Exhibits 2-2 and 2-3).
3. Noncombustible sheathing shall be installed above any combustible roof sheathing and framing. The noncombustible sheathing may be installed above or below the roof membrane and/ or insulation. This project: Not applicable.
4. Selective smoke detection coverage shall be installed in the Type Ill portion of the building per NFPA 72, National Fire Alarm Code, beginning at the access point to the path of egress and continued until reaching all exits. Should the exit discharge into a lobby or other intervening space, selective smoke detection coverage requirements shall be extended to such spaces until reaching the exit discharge. This project: This work is Design-Build and will be made part of their work.
5. At least one operable exterior window shall be provided in each dwelling unit with a minimum opening width of 3-1/2". This project: All dwelling units meet this minimum requirement.
6. Wall and floor assemblies separating dwelling units shall have fire-resistance ratings of not less than 1 -hour. This project: All wall and floor assemblies separating dwelling units are 1-hour rated.
7. The base allowable building area specified in the Structural Specialty Code for R occupancies in Type 111-A construction shall not exceed 12,000 square feet. Area increases in accordance with the Structural Specialty Code are allowed. This project: allowed area increases bring our R-2 building areas into compliance.
8. The distance from the top of the roof parapet to the lowest required fire apparatus setup point, as determined by the Fire Marshal's Office, shall not exceed 75 feet. A minimum of one dominant street­ facing building fa9ade shall meet Fire Code requirements for fire apparatus aerial access.

This project: distance from top of roof parapet to lowest fire apparatus set up point is in compliance. Cook Street meets the Fire Code requirements for fire apparatus aerial access.

1. All required egress stairs shall include access to the roof. Such access may be via any method listed in OSSC Chapter 10 for roof access. This project: all four egress stairs extend to approved roof hatches at the roof.
2. All penetrations through the exterior wall covering shall be fire-stopped at the exterior sheathing. "Penetrations for purposes of this Code Guide includes elements such as conduits and piping and does not include "openings" such as doors, windows, or wall-mounted HVAC units and louvers. This project: complies.
3. Ducts and vents penetrating exterior wall shall be 26ga minimum. This project: complies.
4. No unprotected penetrations are permitted through the underside of fire-rated exterior wall projections required to be rated, including cornices, eaves, bays, exterior balconies and similar projections extending beyond the exterior wall. This project: complies.
5. Elevator hoistway openings directly into corridors shall have smoke-tight protection as required for doors opening into fire-resistive corridors. This project: complies.

The applicant wishes to replace fire-retardant wood framing with non-fire-retardant wood framing primarily for reasons of cost and constructibility. The costs associated with the City's revocation of Chapter 24.95 "Special Design Standards for Five Story Apartment Buildings" which previously allowed Type VA Construction are substantial.

By employing the aforementioned Code Guide directive from Paul Scarlett, as well as direction from our Preliminary Fire Life Safety Meeting at which we obtained approvable details for similar 5 over 1 projects recently approved by the City, we have provided an equivalent degree of structural capacity, life safety and fire protection. Likewise, the enclosed fire-rated sheathing alternative has been previously approved for use in the City of Portland. We are seeking approval for it's use as defined above.