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BCC Ruling No. 01-07-800

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

AND IN THE MATTER OF Article of Regulation 403, as amended by O. Reg. 22/98, 102/98, 122/98, 152/99, 278/99, 593/99, 597/99 and 205/00 (the "Ontario Building Code").

AND IN THE MATTER OF an application by Mr. Dan Vernescu, Property Manager, Town of Oakville, Ontario, for the resolution of a dispute with Mr. Frank Asta, Chief Building Official, Town of Oakville, Ontario, to determine whether the proposed air distribution system that is comprised of under-slab combustible duct piping provides sufficiency of compliance with Article of the Ontario Building Code at the Oakville Municipal Building, 1225 Trafalgar Road, Oakville, Ontario.

Mr. Dan Vernescu, Property Manager
Town of Oakville
Oakville, Ontario

Mr. Frank Asta
Chief Building Official
Town of Oakville

Dr. Kenneth Peaker, Chair
Mr. Fred Barkhouse
Mr. Donald Pratt

Toronto, Ontario

February 15th, 2001

February 15th, 2001

Mr. Gunnar Heissler, President
The ECE Group Ltd.
Toronto, Ontario
Agent for the Applicant

Mr. Frank Asta
Chief Building Official
Oakville, Ontario
The Respondent


1. The Applicant

Mr. Dan Vernescu, Property Manager, Town of Oakville, Ontario, has received a building permit under the Building Code Act, 1992 to renovate and construct an addition onto the Town of Oakville's municipal building located at 1225 Trafalgar Road, Oakville, Ontario.

2. Description of Construction

The Applicant is renovating and expanding an existing municipal building classified as having a Group D - Business and Personal Services occupancy. The building is two storeys in building height, 14,054 m2 in building area (existing and new) and of noncombustible construction. The addition consists of a new office complex with an atrium (considered as an interconnected floor space) that provides a link to the existing building. Both the existing building and the new addition are sprinklered and equipped with a fire alarm system and a standpipe and hose system.

The construction in dispute involves an installed under-slab air circulation system consisting of plastic duct piping. This pipe, known as "Big O", is made of reinforced high molecular weight, high density polyethylene and is approved as a sewer pipe for underground applications. The Applicant is proposing to use the disputed system as an air carrying facility that is to provide both air cooling and ventilation. As a result, the air temperature in the system will range from 13 to 300 C.

The subject combustible ducts are entirely confined within the newly constructed two-storey high atrium and are to serve only the same area. Specifically, the duct design consists of a central supply main that runs much of the length of the atrium and measures 915 mm (36 inches) in diameter. Five branch ducts 457 mm (18 inches) in diameter run from the main supply duct and terminate at vertical concrete plenums that are to pass the air up and through the floor slab. When completed, the upper (above slab) portions of the concrete plenums are to be incorporated into fixed bench seating located within the atrium. The air outlets, to be covered with low velocity metal grills, will be positioned 200 mm above the floor level, on the side of the benches.

At the supply end of the plastic ducts, the main duct will connect to a noncombustible (metal) vertical shaft that leads to the roof. A power-operated air handler located on the roof supplies the shaft, and thereby the entire system, with air. Part way down, the shaft will have a horizontal offset as air travels through the system.

The combustible pipes within the duct system therefore all run horizontally. The vertical elements of the system, the metal supply duct and the concrete plenums, are noncombustible.

In terms of fire safety, at the connection point between the vertical metal duct and the horizontal combustible duct a fire damper will be installed to provide fire stopping. The system will also be provided with heat and smoke detectors that, when actuated, will stop the operation of the supply fan.

According to the original drawings submitted for building permit, the under floor conduit was to be constructed of concrete. Later, during construction the concrete pipe was substituted with the reinforced Big O plastic piping.

3. Dispute

The issue at dispute between the Applicant and Respondent is whether the proposed air distribution system that is comprised of under-slab combustible duct piping provides sufficiency of compliance with Article of the Ontario Building Code.

Article addresses materials that can be used in air duct systems. Sentence requires that all ducts, etc., be made of similar noncombustible materials. Sentence (2) provides an exemption to Sentence (1) if the criteria laid out in Clauses (a) to (f) are met. Since the proposed material does not fulfill these requirements, the exemption offered in Sentence (2) does not apply.

At issue therefore is wether the installed plastic duct piping at the Oakville Municipal Building, used as a portion of an air distribution system for cooling and ventilation purposes, provides sufficiency of compliance with OBC requirements mandating that air conduits must be noncombustible.

4. Provisions of the Ontario Building Code

Article Materials in Air Duct Systems

  1. Except as provided in Sentences (2) to (4) and in Article, all ducts, duct connectors, associated fittings and plenums used in air duct systems shall be constructed of similar noncombustible material.

  2. Ducts, associated fittings and plenums are permitted to contain combustible material provided they
    1. conform to the appropriate requirements for Class 1 duct materials in CAN/ULC-S110-M, "Standard Methods of Test for Air Ducts",
    2. conform to Article in a building required to be of noncombustible construction,
    3. conform to Subsection 3.1.9.,
    4. are not used in horizontal runs in a building required to be of noncombustible construction,
    5. are not used in vertical runs serving more than 2 storeys in a building required to be of noncombustible construction, and
    6. are not used in air duct systems in which the air temperature may exceed 120C (248F).

5. Applicant's Position

The Agent for the Applicant submitted that the proposed duct material is "safe, functional, durable and potentially superior" to the type of materials addressed by the Code. In his view, it meets and exceeds the intent of Code requirements. As a result, he argued that the substitution of the Big O material "does not violate the terms and conditions of the building permit." (Although he did acknowledge that the contractor was "proactive" in terms of the pipe installation.) The Agent then stated he would focus his arguments along the following themes; safety, functionality and "approvability".

Regarding the safety of the Big O product, the Agent indicated that the proposed ducts are used extensively as thermo-plastic conduits, drainage piping or culverts in buried applications. These installations, he argued, have just as much potential exposure to exterior fires as can be anticipated for those in the Oakville Municipal Building. The Agent noted that, to his knowledge, he is not aware of any incidents nor failures in this regard to date.

The Agent continued that, in addition to sprinklering of the entire building and having a smoke control system in the atrium, additional fire safety measures are proposed in connection with the proposed air duct system. Included in these measures is the installation of a fire damper at the connection between the vertical supply shaft and plastic ducts (to be located at the floor line) to separate the combustible portion of the subject air supply system from the remainder of the building. The system also contains a heat and smoke detectors that will shut down air movement in case of a fire. The Agent also argued that the system is safe because the plastic portion is buried within ground and under concrete and is thereby protected from direct heat radiation (if a fire were to occur) and other exterior influences.

Moreover, the chance of a fire occurring in the pipe is remote, the Agent stated. All portions of the system above ground are noncombustible. The outlet grills in the plenums, located 200 mm above the floor level, protect the exhaust end of the system from refuse and combustibles. At this height, no materials such as cigarettes can get swept into the system. As well, the plastic pipes have no heat source and no fuel load, except the pipe itself.

The pipe is also safe with respect to microorganism growth. As he argued, concrete is porous and allows fungal contamination. The Big O has no porosity and therefore "is completely immune from colonization of microorganism such as fungii (sic)." The Respondent's claim that the corrugated form of the pipe creates grooves on the interior is not true. The pipe is smooth on the inside. It is only the exterior that is corrugated to provide structural strength. There are no grooves inside the pipe where water could accumulate and cause microorganism growth. Besides, any water that may get into the system would evaporate when in operation.

Regarding the functionality of the pipe, the Agent argued that the Big 'O', as a sewer pipe, has been designed to withstand the same soil pressures for underground applications as the one in dispute. In addition, these pipes have a life expectancy of 65 years above ground and ageless when buried underground. The durability of the material was supported by a representative of the Big O product that attended the hearing.

As far as the approvability of the subject material is concerned, the Agent noted that the Big O pipe is very common and is used extensively. He noted, however, that the OBC does not seem to directly address the use of products such as the Big O for this type of application. Instead, for under floor air distribution systems it seems to rely extensively on referenced standards. These standards, however, he indicated support the use of under floor plastic air ducts. Indeed, ASHRAE, SMACNA, NFPA 91 and the International Mechanical Code Issue 2000 all endorse the use of material (as found in the Big O) as appropriate for the disputed application.

As the Agent argued, if the subject air system were to be viewed as part of the floor, it appears to conform to Code requirements for under floor air distribution systems. It also complies with provisions in the Code that require non-metallic (plastic) components of duct systems to have operating temperatures of up to 490 C. As he noted, the installed material is approved for an operating temperature of 600 C or higher.

The Agent concluded by stating that the ultimate goal of the air system in dispute was to achieve functionality, while providing safety. It is his belief that the duct system is very safe. It is a single use duct to serve a single space within a building that is sprinklered. The fire safety intent of the OBC therefore has been met. The Big O product is appropriate in this application, the Code simply does not address such usage at this point.

6. Respondent's Position

The Respondent submitted that the plastic pipes, used as air distribution ducts, are combustible and therefore do not meet Article of the Code. Specifically, the Big O pipe does not qualify under the exemptions to the noncombustible material requirement (Sentence found in Sentence The flame spread rating and the smoke development classification for the product exceed the permitted limits for air distribution systems set out in the CAN/ULC S110-M Standard, which is referenced by the OBC.

The Respondent argued that the pipe has not been tested for the use proposed by the Applicant as air duct system. Article does allow combustible materials to be used in air carrying facilities, however these systems must comply with certain standards. This system does not. He noted that, to his knowledge, no other examples exist in which this material is employed for air handling. In fact, the Respondent explained that he had contacted the manufacturer of the product who indicated that they did not recommend the Big O system for use as air ducts. In addition, there is no evidence to prove the equivalency of the proposed material to those addressed by the Code.

The Respondent stated that his main concern is that the subject combustible air duct system will serve a large atrium space that can accommodate between 300 to 400 people. And since the duct system contains a considerable amount of pipe, an extensive volume of combustible material has been introduced into the atrium. He noted that the Fire Department of Oakville has expressed concern regarding this increased fuel load, in particular the potential amount of deadly CO2 (carbon dioxide) that could be released into the building if the duct system were ever to ignite.

The pipe also appears to be corrugated on its interior, the Respondent noted. Such grooves may allow for the accumulation of moisture. This in turn may lead to the production of bacteria and other organisms, such as Legionnaires Disease.

The Respondent concluded by indicating that this change of pipe product was not shown on the plans submitted for permit and was not discussed and approved prior to installation. Lastly , he stated that the duct piping neither complies with Code requirements, nor does it meet the level of fire safety intended by the OBC.

7. Commission Ruling

It is the decision of the Building Code Commission that the proposed air distribution system comprised of under-slab combustible duct piping provides sufficiency of compliance with Article of the Ontario Building Code at the Oakville Municipal Building, 1225 Trafalgar Road, Oakville, Ontario on condition that:

  1. The duct system serves only the atrium; and,

  2. The duct system be used to convey only ventilation air and air-conditioned (cooled) air, and not for any other purpose.

8. Reasons

  1. The subject duct plays a limited role in the total air carrying of the building.

  2. There are no structural concerns related to this application.

  3. The atrium will be provided with an engineered smoke control system.

  4. This particular installation does not present a fire hazard since the duct is completely buried under the floor slab, the supply duct to the underground duct is noncombustible and equipped with a fire damper, and air is discharged into occupied areas through noncombustible plenums.

    Dated at Toronto this 15th, day in the month of February, in the year 2001 for application number 2001-11.


    Dr. Kenneth Peaker, Chair


    Mr. Fred Barkhouse


    Mr. Donald Pratt