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BCC Ruling No. 97-27-569

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AND IN THE MATTER OF Article and Subsection 3.1.6. of "the Building Code" (Ontario Regulation 419/89 as amended by Ont. Reg. 183/88, 581/88, 11/89 and 115/89).

AND IN THE MATTER OF an application by Mr. Karl Stennson, Vice President, Sheridan Nurseries Ltd., R.R. #4 - 12302 10th Line, Georgetown, Ontario, for the resolution of a dispute with Mr. John Wright, Director of Building Standards, Town of Markham, concerning whether the proposed polyethylene skylight should be considered a roof according to Article of the Ontario Building Code (OBC) and whether the open-sided sales facility with polyethylene rain shields is a tent under OBC Subsection 3.1.6. at Sheridan Nurseries, 4077 Highway # 7, Town of Markham, Ontario.


Mr. Karl Stennson
Vice President
Sheridan Nurseries Ltd.
R.R. #4 - 12302 10th Line
Georgetown, Ontario


Mr. John Wright
Director of Building Standards
Town of Markham


Mr. Roy Philippe, Chair
Mr. Michael Lio
Mr. Michael Steele

Toronto, Ontario

Wednesday, July 9th, 1997

Mr. Karl Stennson Vice President
Sheridan Nurseries Ltd.
The Applicant

Mr. Allan Larden
Larden Muniak Consultants
Agent for the Applicant

Mr. John Wright
Director of Building Standards
Town of Markham
The Respondent

Mr. Chris Bird
Manager of Plans Review
Town of Markham
For the Respondent


  1. The Applicant

Mr. Karl Stennson, Vice President, Sheridan Nurseries Ltd., is a person who has applied for a permit under the Building Code Act, 1992 to renovate an existing, enclosed wood frame building to provide for an expansion of their current retail area and to construct a new open-air, covered sales facility at Sheridan Nurseries Ltd., 4077 Highway # 7, Town of Markham, Ontario.

  1. Description of Construction

The existing building at Sheridan Nurseries in Markham is a 30 year old, enclosed, one storey structure that has been used for nursery-related sales and as a greenhouse. The building is 600 m2, which includes a 160 m2 greenhouse. It is composed of combustible construction and is classified as having a Group E (mercantile) major occupancy. Currently, the structure does not have a standpipe and hose, fire alarm, nor a sprinkler system.

The proposed work at Sheridan Nurseries has two separate components. One of these is the renovation to the above described existing building, while the other is the construction of a new open-air sales facility. To distinguish between these two aspects of the project, the former shall be known as the enclosed retail building, while the latter shall be called the covered sales facility.

Regarding the enclosed retail building, the Applicant proposes to demolish the existing greenhouse and replace it with a one storey, enclosed addition. The total area of this renovated building would be 1 435 m2 (15 447 ft2). This would include a small office area (382 ft2), a storage area (2 268 ft2), while the rest of the space would be devoted to retail sales. The conventional, solid roof covering the existing building will remain in place. The addition to the enclosed retail building, however, will be covered by a polyethylene roof system manufactured by Westbrook Greenhouse Systems Ltd. The roof assembly is a modular greenhouse system composed of two 6 mm layers of polyethylene sheets, with pressurized air between them to increase rigidity, supported on a steel frame. The walls of the addition will be constructed of aluminum thermowall panels and tempered glass in aluminum frames.

The design of the enclosed retail building will allow for fire route access from 3 streets. As such, it is not necessary that the building be equipped with a standpipe and hose system and a sprinkler system. This is also allows it to be made of unrated combustible construction. The occupant load, based on OBC Table 3.1.16.A., is deemed to be 388 persons. By exceeding 300 persons, according to OBC 3.2.4., a fire alarm and detection system will be installed. The building will also be equipped with portable fire extinguishers. Furthermore, egress from the enclosed sales building will be based on 6.1 mm width per person and the exits will be located so that the maximum distance of travel will be 30 m or less.

The covered sales facility, located roughly 3 m from the enclosed sales building, is an entirely new structure. It is intended that this facility be open air, i.e., constructed without walls. The proposed use of this 1 615 m2 (17 388 ft2) structure is as a seasonal sales area. The roof for the covered sales facility is exactly the same as that described for the addition to enclosed sales building.

This structure, if it were assumed to be a typical mercantile occupancy, the potential occupant load would be 437 persons. Having no walls, egress from the covered sales facility is not a concern. The maximum travel distance from any where inside this structure to beyond the perimeter of the roof will not be more than 30 m.

  1. Dispute

There are several issues under dispute between the Applicant and the Respondent. The first issue is whether the polyethylene roof assembly for the proposed addition to the enclosed sales building should conform to the requirements of Article of the OBC. This provision states that all buildings shall have a class A, B or C roof, with the exception of tents and air supported structures. The Respondent holds that the polyethylene roof should conform to The municipality is also concerned that the polyethylene roof assembly has not been tested for conformance with the appropriate safety standards (CAN/ULC S-107-M87) as referenced in Sentence The Applicant, on the other hand, believes that this Article is not applicable to polyethylene "skylights".

The second issue is whether the open-sided covered sales facility, with its polyethylene roof membrane, should be governed by the requirements of Subsection 3.1.6., which deal with tents, air-supported and temporary structures. The Respondent believes that the covered sales facility is a tent and that the provisions of 3.1.6. are relevant. They also believe that, according to Article, the facility should comply with the requirements of CAN/ULC S-109-M, which sets out standards for flame-resistance of materials found in tents, etc. The Applicant holds that the covered sales facility is not a tent, meaning that 3.1.6. are not relevant.

A third issue, common to both proposed structures, is whether the roof systems demonstrate sufficiency of compliance with the various relevant provisions of the OBC.

  1. Provisions of the Building Code Roof Coverings

(1) Except as provided in Sentence (2), every building shall have a Class A, B or C roof covering as described in Subsection 3.1.15.

(2) Roof coverings are not required to have a Class A, B or C rating for

(a) tents and air-supported structures, and

(b) buildings of Group A, Division 2 occupancy not more than 2 storeys in building height and not more than 1 000 m2 (10,800 ft2) in building area provided the roof covering is underlaid with noncombustible material.

3.1.6. Tents, Air-Supported Structures and Temporary Structures Means of Egress

Tents, air-supported structures and temporary structures shall conform to Section 3.3 and 3.4. Application

(2) Air-supported structures shall not be used for Groups B, C or Group F, Division 1 major occupancies or for classrooms.

(3) Air-supported structures shall be designed primarily as open floor space without interior walls, mezzanines, intermediate floors or similar construction.

(5) For the purposes of this Subsection, a temporary structure means a building or structure intended to be erected and used for a period of not more than 12 months. Clearance to Other Structures

(1) Except for tents used for camping and other personal uses and except as provided in Sentences (2), (3) and (4), every tent, air-supported structure and temporary structure shall conform to Subsection 3.2.3.

(2) Tents and air-supported structures shall not be erected closer than 3 m (9 ft 10 in) to other structures on the same property except as provided in Sentences (3) and (4), and shall be sufficiently distant from one another to provide an area to be used as a means of emergency egress. Clearance to Flammable Material

The ground enclosed by a tent or air-supported structure and for not less than 3 m (9 ft 10 in) outside of such structure shall be cleared of all flammable material or vegetation that will carry fire. Flame Resistance

Every tent and all tarpaulins and decorative materials used in connection with tents and air-supported structures shall conform to CAN/ULC S-109-M, "Standard for Flame Tests of Flame-Resistant Fabrics and Films". Design of Temporary Structures

(1) Except for tool sheds or similar structures, the structural components of a temporary structure shall be designed in conformance with

(a) Subsection 4.1.6. for the intended use,

(b) Subsection 4.1.7. for snow and rain, and

(c) Subsection 4.1.8. for wind.

  1. Applicant's Position

The Applicant submitted that the proposed roof membrane for both the enclosed sales building and the covered sales facility is not a "roof covering". They argue that the classes of roof structures described in Article are intended for typical, permanent roof coverings that have a water-resistant material applied as an additional layer. The CAN/ULC S-107-M standard is designed to test the fire resistance of these water proofing layers, especially the potential for a fire to develop on top of a solid roof covering. Such a situation, the Applicant notes, cannot occur on a polyethylene film. The fire would simply burn through the polyethylene. The Applicant therefore concludes that the referenced roof standard does not apply. In their view, the proposed roof structures are essentially large skylights, and in their experience CAN/ULC S-107-M also does not apply to skylights.

The Applicant holds that permitting the enclosed sales facility under the OBC is a straightforward matter. The Building Code, they argue, allows certain single storey buildings to be built with unrated, combustible construction. The interior flame-spread rating of such a building must not exceed 150. As the Applicant notes, the proposed polyethylene assembly meets both these conditions. Further, because there are no corridors requiring fire-separation from other parts of the floor area, they feel that there would be no limits placed on a combustible skylight (OBC Indeed, the Applicant notes that the Building Code would allow them to virtually cover the entire roof of a combustible building with acrylic skylights. However, as they point out, acrylic skylights have a higher flame-spread rating, and because they are double glazed they have a greater fire load and consequently a higher fire hazard.

In their opinion then, sufficiency of compliance is not an issue regarding this building. As demonstrated above, they believe the building does comply with the relevant OBC provisions.

The Applicant also submitted that polyethylene, as a material, has been tested under ULC S-102.2 and was found to have a flame-spread rating of less than 25. They also noted that this type of polyethylene-covered greenhouse system has been used previously in Ontario.

The same argument regarding limitlessness of skylights can be applied to the covered sales facility. This structure is classified as a Group E occupancy. The maximum size of a combustible building with such an occupancy is 1 500 m2 (16 100 ft2). The proposed covered sales facility exceeds this limit by 115 m2. This larger capacity is tolerable, the Applicant argues, due to the fact that the covered sales area has no walls, any fire that started would spread slowly because of the small fire load represented by the polyethylene. Such a fire would likely not cause many problems concerning gases or smoke. The polyethylene covering above the fire would burn away quickly and the fire would vent up and out of the facility, or it would vent along the arches of the ceiling and out the open sides. In addition, egress is possible in many locations and the travel distance is less than 30 m. It is for these reasons that the Applicant believes that the covered sales facility does meet the intended level of life safety in the OBC and as such provides sufficiency of compliance.

The open-sided, covered sales facility is not a tent the Applicants also argue. The proposed structure has little in common with a tent. Although to be used seasonally, the covered sales facility has far more permanence. As well, unlike a typical tent, there are no walls. The facility is not air-supported either, the Applicants claim. The pressurized air in between the polyethylene films is not a vital support mechanism for the roof assembly. Based on these arguments, the Applicant is of the opinion that the covered sales facility should not be subject to the requirements of Subsection 3.1.6.

  1. Chief Building Official's Position

The Respondent submitted that the proposed enclosed sales building is required to have a class A, B or C roof covering according to Sentence and the CAN/ULC S-107-M87 standards. In their view, the subject polyethylene roofing material had been adequately tested for conformance with the above referenced standard.

Regarding the covered sales facility, the municipality recognized that it was a difficult building to classify, nevertheless they felt that it would be appropriate to consider this structure as a tent and to apply the provisions of 3.1.6. Such a classification would allow the covered sales facility to be located within 3 m of the enclosed sales building. This would also allow the Applicant the opportunity to be released from the requirement to provide sprinklers, they added. Here too, however, they were concerned about the performance of the polyethylene with respect to flame-resistance.

  1. Commission Ruling

It is the decision of the Building Code Commission that the polyethylene film covering the

Sheridan Nurseries retail building provides sufficiency of compliance with Article of the Building Code and the covered sales facility using a rain shield of polyethylene film is for the purposes of the application of the Building Code considered a tent and the fabric provides sufficiency of compliance with Article of the Building Code and the tent is subject to the spatial separation requirements of Article of the Building Code.

  1. Reasons:

i) The building is used as a garden centre and contains limited fuel load.

ii) Opinion evidence provided by ORTECH on polyethylene flame spread indicates a value of less than 25 as an interior finish.

iii) The test for fabric flammability conducted by ORTECH using standard ASTM D-635 provides data on the limited ability of the film to propagate flame.

iv) The building is permitted to be of combustible construction under the Building Code.

v) The enclosed retail building will satisfy all other Building Code requirements including structural, fire alarm and egress.

vi) The fuel load for the polyethylene film used is approximately 20 times less than for other rigid plastics.

vii) The film will melt away and vent fires under fire conditions.

viii) It is the opinion of the Building Code Commission that the proposed use of polyethylene film in this application does not increase the hazard to life safety from fire.

Dated at Toronto this 9th day in the month of July in the year 1997 for application number 1997-27.

Roy Philippe, Chair

Michael Lio

Michael Steele