Appeal 8462

Sections 703, 709, 1018

OSSC Section 703 — Fire-resistance ratings for walls and ceilings. Provide listed assemblies for fire resistive walls and ceilings as required for rated corridor construction and fire partitions separating sleeping rooms. (Item #6 of the Life Safety Check sheet)

OSSC Section 709 — Fire Partitions, Section 709.3 exception 1 & 2 states that corridors and fire partitions separating sleeping rooms shall be % hour rated. Section 709.4 requires fire partitions to extend from the top of the foundation (in our case a slab floor) to the fire-resistance rated floor/ceiling or roof/ceiling assembly above. If the partitions are not continuous to the sheathing, deck or slab, and where constructed of combustible construction, the space between the ceiling and the sheathing, deck or slab above shall be fire-blocked or draft-stopped in accordance with Section 717.2 and 717.3 at the partition line. (Item #7 of the Life Safety Check-sheet)

OSSC Section 1018 — Corridors, Table 1018.1 Corridor Fire-Resistance Rating requires the corridors of an R occupancy with greater than 10 occupants to be % hour rated when provided with a sprinkler system. (Item #15 of the Life Safety Check-sheet)

The proposed design demonstrates how the existing and modified construction will provide for the
required 1/2" hour (30 minute) fire rated corridor construction and fire rated separation of sleeping rooms. It should be noted that the existing building was previously rated type V-1 hour. Because the facility is currently provided with a fire sprinkler system that will be maintained and upgraded, we have designated the building as type V-B which will be adequate for the proposed use.

The following drawings are attached:
-An overall floor plan of the existing building with the proposed modifications shown. -A partial floor plan showing a typical corridor and keyed in section 4/A3.1.
-Section 4/A3.1 showing a typical corridor.
-Section 5/A5.3 which shows the corridor construction in greater detail.

Note: only the corridor section is being shown, but the fire partitions between the sleeping rooms will be constructed in the same way.

Following is a detailed description of the proposed fire rated corridors and fire rated separation of the sleeping rooms:

1. The existing corridor walls are constructed with 5/8" type x gypsum wall board on each side of 2 x 4 wood studs spaced at 16" o.c. Any new or infill walls will have the same construction. The walls run from the existing concrete slab up to the underside of the existing 2 x 8 ceiling joists that are spaced at 16" o.c.
2. The existing ceiling is constructed with one (1) layer of 5/8" type x gypsum wallboard attached directly to the bottom of the ceiling joists. The ceiling joists have (1) layer of 15/32" APA rated exterior grade plywood with a torch down roof over that. There is currently 2 x 6 blocking provided between the ceiling joists at all of the corridor wall plates. There was a 2" gap at the top of this blocking in order to obtain ventilation above the roof insulation. This insulation will be removed and addition 2 x 8 blocking will be provided to provide complete fire blocking between the walls and the roof sheathing.
3. The intent is to remove the existing 5/8" type x GWB at the ceiling in order to mitigate for the asbestos texture materials at the ceiling. The blocking mentioned in item 2 will be installed and one (1) new layer of 5/8" type x GWB will be applied to the bottom of the ceiling joists. This will make up the fire rated walls and ceiling construction.
4. In addition, --- proposed "Solatube" skylights will be provided with a shaft wall with a minimum of 30 minute fire rating where the tubes penetrate the attic space.
5. The living spaces and the attic space will be provided with sprinkler heads. This system is currently being designed by Crown Fire Systems.
6. All ducts penetrating the fire rated walls and ceiling will be provided with fire dampers. 7. I would also like to note that the attic space that will be created from the addition of sloped roof

trusses is not occupied or usable space. The slope is simply being added in order to provide a
better roof system for shedding water and to protect the HVAC units and ducts.

The walls described above currently meet the requirements for a 1 hour rated wall as depicted in GA File No. WP 3514. We have not been able to find any tested wall systems that are rated for 1/2 hour and therefore propose to use the walls rated for 1 hour. The existing and new ceiling described above do not meet the current requirement for a 1 hour rated system, although it must have at one time since the existing building is listed as a Type V — 1 hour construction type.

Please refer to Table 720.1(3) item 21-1.1 to demonstrate what would be required in order to maintain a 1 hour rating at the ceiling.
-Floor or Roof Construction: Wood joists spaced a maximum 24: o.c. with 1/2" wood structural panels with exterior glue applied at right angles to tope of joists with 8d nails.
-Ceiling Construction: (2) layers of 5/8" type x gypsum wallboard (abbreviated).

Our proposal is to provide the same roof/ceiling construction except with only (1) layer of 5/8" type x gypsum wallboard instead of (2) layers because the rating required is only'/2" hour, not 1 hour. As demonstrated in Table 721.6.2(1), one layer of 5/8" type x gypsum wallboard is rated for 40 minutes. 15/32" wood structural panel is rated for 10 minutes. According to Section 703.3, calculating the fire resistance of materials according to Section 721 is an alternative method for determining fire resistance.

Following are some of the reasons that the proposed construction will exceed the fire rated construction requirements.

1. As demonstrated above, we believe that the proposed construction provides at least the minimum required 1/2" hour fire rating and in many cases more.
2. Even though the construction classification of the building will be changed to a type V-B, most of the existing construction that was classified as type V-1 hour will remain.
3. All of the doors in the corridor will be replaced so they will have all of the current certifications for fire rated doors.
4. Building is fully protected by an automatic fire sprinkler system in accordance with 903, NFPA 13. 5. Building is provided with smoke detectors and annunciation system throughout.