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BCC Ruling No. 99-18-674

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BUILDING CODE COMMISSION DECISION ON B.C.C. #99-18-674

IN THE MATTER OF Subsection 24 (1) of the Building Code Act, 1992.

AND IN THE MATTER OF Sentence 3.6.3.1.(1) of Regulation 403, as amended by O. Reg. 22/98, 102/98 and 122/98 (the "Ontario Building Code").

AND IN THE MATTER OF an application by Mr. Idwal Richards, President, Pye & Richards Architects Inc., 824 Meath Street, Ottawa, Ontario, for the resolution of a dispute with Mr. Kaz Mosielski, Chief Building Official, City of Kanata, Ontario to determine whether the fire separations not required to have a fire-resistance rating proposed to surround the vertical service shafts and to be constructed of 92 mm steel studs and 12.7 mm gypsum board and sealed at the perimeter and at all penetrations provides sufficiency of compliance with Sentence 3.6.3.1.(1) of the Ontario Building Code at the Kanata Research Park, 309 Legget Drive, Kanata, Ontario.

APPLICANT

Mr. Idwal Richards, President
Pye & Richards Architects Inc.
Ottawa, Ontario

RESPONDENT

Mr. Kaz Mosielski
Chief Building Official
City of Kanata

PANEL

Mr. Roy Philippe (Chair)
Mr. Robert De Berardis
Mr. James Lischkoff

PLACE

Toronto and Ottawa, Ontario

DATE OF HEARING

March 24, 1999

DATE OF RULING

March 24, 1999

APPEARANCES

Mr. Dave Seaborn, Architect
Pye & Richards Architects Inc.
Ottawa, Ontario
Agent for the Applicant

Mr. Tim Stewart
Building Official
City of Kanata
For the Respondent

RULING

  1. The Applicant

Mr. Idwal Richards, President, Pye & Richards Architects Inc., has applied for a building permit under the Building Code Act, 1992 to construct a new, low-rise office building, known as the Kanata Research Building, at 309 Legget Drive, Kanata, Ontario.

  1. Description of Construction

The Applicant proposes to construct a new, three storey, Group D - office occupancy with a building area of 2,036 m2. A portion of the structure will also contain a Group F, Division 3 - low hazard industrial occupancy. The building will be noncombustible construction. It will be equipped with a fire alarm and sprinkler system.

The construction in dispute concerns the proposed fire separation, which is not required to have a fire-resistance rating, that is to enclose the duct shafts (vertical service space) throughout the three storey building. The Applicant proposes to install an assembly consisting of one layer of 12.7 mm drywall on only one side of 92 mm steel studs. This assembly would be taped and sealed at the perimeter and all penetrations.

  1. Dispute

The issue at dispute between the Applicant and Respondent is whether the proposed fire separation assembly, that is not required to have a fire-resistance rating, complies with Sentence 3.6.3.1.(1) of the Ontario Building Code. This provision requires that the separation for the vertical service space be determined based on the rating of the floor assembly required for the subject building as found in Table 3.6.3.1. In the building at dispute, since the floor assemblies are permitted to have a rating of less than 45 minutes, Table 3.6.3.1. indicates therefore that the vertical service space is not required to have a fire-resistance rating, in other words it is permitted to be an unrated fire separation. The issue thus centres on whether the proposed assembly for the vertical service space can be considered an unrated separation and whether it would perform as required by the Ontario Building Code.

  1. Provisions of the Ontario Building Code

Sentence 3.6.3.1. Fire Separations for Vertical Service Spaces

(1) Except as required by Section 3.5., a vertical service space shall be separated from all other portions of each adjacent storey by a fire separation have a fire-resistance rating conforming to Table 3.6.3.1. for the fire-resistance rating required by Subsection 3.2.2. for

(a) the floor assembly above the storey, or

(b) the floor assembly below the storey, if there is no floor assembly above.

  1. Applicant's Position

The Applicant submitted that the proposed fire separation, with drywall on one side only, provides sufficiency of compliance with Sentence 3.6.3.1.(1) of the OBC. They offered the following arguments to support this view.

At the outset the Applicant indicated that both he and the Respondent agree that the subject noncombustible building is not required to have floor assemblies with a rated fire separation. Referring to Table 3.6.3.1., it follows, he also indicated, that both parties agree that the vertical shaft walls are permitted to be separations without a fire-resistance rating.

In the Applicant's view, as an unrated separation, the subject assembly is required to act as primarily a smoke barrier with minimal ability to withstand fire. In terms of providing a barrier to smoke, he argued that the vertical service shaft constructed with a single layer of drywall on the outside and taped and sealed at the perimeter and at all penetrations is sufficient. Because the proposed separation is considered noncombustible and is continuous and completely sealed, it is entirely adequate to perform this function.

The Applicant also argued that it does act to some degree as a barrier against the spread of fire in accordance with the definition of fire separation found in Article 1.1.3.2. and A-3.1.8.1. (1)(b) of the OBC Appendix, the latter of which requires a separation to stay in place "until some response is initiated." He indicated that an assembly with drywall on one side would likely stay in place for approximately 10 to 15 minutes (even with a fire occurring on the inside of the service shaft), which would be long enough to withstand fire until the sprinklers have activated.

The Applicant offered correspondence from the Canadian Codes Centre and the Ministry's Housing Development and Buildings Branch which indicated that the proposed assembly would comply with the requirements for an unrated separation.

Lastly, the Applicant argued that the construction of the proposed assembly is quite common and is accepted in other municipalities throughout the province.

  1. Respondent's Position

The Respondent submitted that the proposed vertical service shaft separation assembly does not comply with Sentence 3.6.3.1.(1).

As they argued, since the enclosure around the vertical service space is considered a fire separation, it must meet the definition of fire separation in the OBC, which is an assembly that "acts as a barrier against the spread of fire". The Respondent also point to the OBC Appendix which indicates that a fire separation should perform its function until some response is initiated, i.e., activation of the sprinkler system. To perform its function as a separation until the sprinkler system is activated means that the assembly must remain in place for approximately 15 minutes. In other words, even an unrated separation requires at least some degree of fire-resistance rating. In their view, however, the steel studs of the proposed assembly, when exposed to fire from the inside, would likely fail well before sprinkler activation.

In order therefore to meet the intent of Sentence 3.6.3.1.(1) they argued that the separation requires a layer of drywall on both sides. Only by having drywall on both sides will the separation have some form of protection from fire exposure from both directions and would therefore ensure its integrity. To support this, the Respondent pointed to OBC Sentence 3.1.7.3.(2) and 2.3.5.(1) of the Supplementary Guidelines, which they argued indicate that interior vertical fire separations should be rated for fire exposure from both sides.

The Respondent also raised concern regarding the structural requirements of the shaft walls. They pointed to Sentence 4.1.10.3.(1) which requires the subject walls to be able to withstand the appropriate lateral design loads. They indicated that unless the vertical service walls were protected from fire exposure on both sides, the steel studs would be significantly weaken and would collapse within minutes. The Respondent submitted a letter from a structural engineering consultant supporting this position.

In conclusion, the Respondent argued that any vertical fire separation, including those permitted to be unrated, must act as a barrier to smoke, and to some degree, fire in order to be able to perform as a separation. Moreover, the only way to achieve this is to have a membrane on both sides of the assembly that would provide a greater degree of over all fire-resistance rating for the assembly and would offer more protection to the structural members.

  1. Commission Ruling

It is the decision of the Building Code Commission that the vertical shaft construction provides sufficiency of compliance with Sentence 3.6.3.1.(1) of the Building Code.

  1. Reasons

1) The building is noncombustible and sprinklered throughout.

2) The ducts penetrating the shaft are noncombustible.

3) The duct shaft is taped and sealed to act as a smoke barrier.

4) The shaft contains no combustible material.

5) The combination of exterior shaft and duct penetrations provide a barrier to smoke and fire spread consistent with A-3.1.8.1.(1) of the Ontario Building Code Appendix.

Dated at Toronto this 24th day in the month of March in the year 1999 for application number 1999-06

Mr. Roy Philippe, Chair

Mr. Robert De Berardis

Mr. James Lischkoff