Appeal 33449

Table 504.4

Requires four stories in an R-3 occupancy to be equipped with a fire suppression system of 13R or 13 system, 13D is only allowed up to three stories.

We are proposing to keep NFPA 13D sprinklers rather than 13R or 13.

NFPA 13D sprinklers are installed throughout the building including the fourth floor attic space that is unfinished and not intended for occupancy.

Per 903.3.1.3 NFPA 13D sprinkler systems are allowed in group R-3 and specifically townhouses. When built, the attic was never classified as an additional story, however, now as a commercial building the unfinished attic is being counted even if it will not be occupied. The building was built per the residential code for townhouse construction and will be used in a near identical manner. NFPA 13D sprinklers have been installed throughout the building including the attic space. Installing a 13R system would be cost prohibitive when the 13D system provides comparative fire coverage.

Reconsideration:
We are proposing to increase the existing 1-hour rated common wall between units to a 2-hour rated fire wall by adding an additional layer of 5/8” type ‘X’ gypsum panel to each side of the wall. This will bring the total to two layers of 5/8” type ‘X’ gypsum panels to each side of the wall. Per table 722.2.1.4(2), 1 layer of 5/8” type ‘X’ gypsum provides 40 minutes, and 2 layers would provide 80 minutes. With the addition of 15/32” wood structural panel each side, this adds an additional 10 minutes per side. The wood stud framing at 16” O.C. provides 20 minutes per side, and with the addition of glass fiber mineral wood batts filling the spaces between studs, this provides 15 minutes of rating. Per exposure side, the total provided fire rating is 125 minutes meeting the 2-hour fire wall requirements. With this added level of safety between units, the 13D sprinkler system should be reconsidered as it provides the same level of safety with the addition of the 2-hour fire wall.

706.4

Fire walls shall have a fire-resistance rating of not less than 2 hours for group R-3.

We are proposing to keep the residential townhouse demising wall as originally constructed to meet R302.2.1(1) with two 1-hour fire-resistant rated wall assemblies.

Built under the residential code, this required townhouse separation by 2-hour fire resistant rated wall assemblies. The project met this requirement with the use of two 1-hour fire rated firewalls, one on each side of the common property line. Each 1-hour rated firewall has a layer of 5/8” type ‘X’ gypsum board on the interior side, 15/32” APA rated structural sheathing, 2x6 stud framing filled with insulation, and a 1” air gap centered on the property line. The fireblocking has been installed at the floor and ceiling joists, and fire rated roof sheathing extends 4 feet on either side of the 2-hour fire resistant fire wall. For additional protection, an NFPA 13D sprinkler has been installed throughout the building that was not required under the residential code.

The commercial building code requires a 2-hour fire resistant firewall and does not make the same distinction as the residential code for the allowance of two 1-hour fire resistant rated walls. The addition of an NFPA 13D sprinkler adds an extra layer of safety to the townhouse construction not originally required. The building is changing from an R3 townhouse to R3 transient use and will be occupied and used in the same manner. Adding an additional layer of 5/8” gyp to both sides of the residential code classified 2 hour fire wall (two 1-hour fire rated walls) would costly to install on four levels from foundation to underside of roof sheathing.

Reconsideration:
We are proposing to increase the existing 1-hour rated common wall between units to a 2-hour rated fire wall by adding an additional layer of 5/8” type ‘X’ gypsum panel to each side of the wall. This will bring the total to two layers of 5/8” type ‘X’ gypsum panels to each side of the wall. Per table 722.2.1.4(2), 1 layer of 5/8” type ‘X’ gypsum provides 40 minutes, and 2 layers would provide 80 minutes. With the addition of 15/32” wood structural panel each side, this adds an additional 10 minutes per side. The wood stud framing at 16” O.C. provides 20 minutes per side, and with the addition of glass fiber mineral wood batts filling the spaces between studs, this provides 15 minutes of rating. Per exposure side, the total provided fire rating is 125 minutes meeting the 2-hour fire wall requirements.

706.5

Fire walls shall be continuous from exterior wall to exterior wall and shall extend not less than 18 inches beyond the exterior surface of exterior walls.

That the use of an NFPA 13D sprinkler system be an acceptable alternative means for complying with 903.3.1.2 (see Appeal 1), and noncombustible sheathing used in the roof construction as part of the two 1-hour fire rated wall system be utilized to meet exception 3 of 706.5.

The existing two 1-hour rated firewalls that separate the unit townhouses extends to the underside of the roof sheathing, including the layer of 5/8” type ‘X’ gypsum board on each side. Fire retardant plywood sheathing is used for a distance of 4 feet extending out on either side of the imaginary property line. Each townhouse has been equipped throughout with NFPA 13D sprinklers for additional protection.

The firewalls as built terminate at the underside of the noncombustible exterior sheathing and the building is now equipped with an automatic sprinkler system. The use of NFPA 13D should be allowed to remain in lieu of a 13 or 13R system that provides similar coverage. In addition, no roof openings are within 4 feet of the two 1-hour rated firewall that extends to the underside of the noncombustible roof sheathing.

Reconsideration:
We are proposing to increase the existing 1-hour rated common wall between units to a 2-hour rated fire wall by adding an additional layer of 5/8” type ‘X’ gypsum panel to each side of the wall. This will bring the total to two layers of 5/8” type ‘X’ gypsum panels to each side of the wall. Per table 722.2.1.4(2), 1 layer of 5/8” type ‘X’ gypsum provides 40 minutes, and 2 layers would provide 80 minutes. With the addition of 15/32” wood structural panel each side, this adds an additional 10 minutes per side. The wood stud framing at 16” O.C. provides 20 minutes per side, and with the addition of glass fiber mineral wood batts filling the spaces between studs, this provides 15 minutes of rating. Per exposure side, the total provided fire rating is 125 minutes meeting the 2-hour fire wall requirements. The revised 2-hour rated fire wall will be continuous to the underside of the roof sheathing that is already built with fire retardant plywood for a distance of 4’ from the centerline of the fire barrier wall.