As our communities and governments recognize the benefits of energy efficiency in construction, the use of foamed plastic insulating materials has also increased. The use of foamed plastic in buildings is considered to be acceptable, provided the foamed plastic is protected in a way that limits risk to occupants and buildings. Foamed plastic materials are permitted in all buildings and all occupancies, even high buildings that fall within the scope of Subsection 3.2.6. and buildings required to be of noncombustible construction in conformance with Subsection 3.1.5.
Background
The 2015 edition of the National Building Code of Canada included the new Article 3.1.5.7. “Factory Assembled Panels”, which was previously found tucked elsewhere in the code. This new Article modified the measurement used to determine the acceptance of a Factory Assembled Panel (FAP) containing foamed plastic from the height measured from grade to the top of the uppermost floor assembly to the underside of the roof assembly. The result of this revision is that many tall, single storey industrial buildings that would have otherwise been permitted to use a FAP, now are prohibited from using a FAP that contains foamed plastic. The 2015 edition also split combustible insulation into Article 3.1.5.14. and foamed plastic insulation into Article 3.1.5.15.
Are All Foamed Plastic Products Impacted?
No, the use of other foamed plastic materials are permitted in all buildings, including high buildings and sensitive occupancies, provided the foamed plastic is protected by a thermal barrier conforming to the new Article 3.1.5.15. “Foamed Plastic Insulation” and protected on the exterior in conformance with Article 3.1.5.6. “Combustible Components in Exterior Walls”
A New Dilemma
Why is a FAP containing foamed plastic treated differently than other assemblies containing foamed plastic? The permission for the use of a FAP containing foamed plastic is limited on the basis that the thermal protection provided by 0.38 mm sheet steel is less than the thermal barriers described in Article 3.1.5.15. and the exterior protection required by Article 3.1.5.6.
If it is true that the protection of foamed plastic that is permitted by Article 3.1.5.7. is less than that required by Article 3.1.5.6. and 3.1.5.15., then we can deduce that Article 3.1.5.7. is an exemption to the protection requirements of Article 3.1.5.6. and 3.1.5.15.
If we agree that the protection provided by a FAP conforming to Article 3.1.5.7. is less than the protection provided by Articles 3.1.5.6. and 3.1.5.15., then the 2015 edition may contain errors, because Articles 3.1.5.6. and 3.1.5.15. do not identify Article 3.1.5.7. as an exemption by containing language such as “except as permitted by Article 3.1.5.7.”.
Currently Articles 3.1.5.6., 3.1.5.7. and 3.1.5.15. all apply independent of each other and each are an independent exemption to Article 3.1.5.1. When have you seen a thermal barrier required to protect a walk-in cooler or freezer, or any other FAP for that matter?
Rule of Thumb
In general, when a code user fails to comply with the criteria of an exemption, the user must default back to the “Rule”.
In this case, if the criteria described in Article 3.1.5.7. for FAP cannot be met, then the code user must default to the more restrictive provision, being Article 3.1.5.15. If the user fails to comply with the criteria described in Article 3.1.5.15., then the user must default back to Article 3.1.5.1. If the user fails to comply with the criteria of Sentences 3.1.5.1.(2), (3), and (4), then the user must default to Sentence 3.1.5.1.(1) and the material must be noncombustible. This procedure is also repeated for the relationship between Article 3.1.5.7. “Factory Assembled Panels” and Article 3.1.5.6. “Combustible Components in Exterior Walls”
To Change or Not to Change…
The proposed changes to the 2020 NBC were released for public review in the winter of 2019. Though the proposed changes attempt to address the issues described above, it appears that the proposed changes do not go far enough.
NRC Proposed Change to Article 3.1.5.6. is shown below. This change proposes to include an exemption for FAP that contains foamed plastic insulation installed on the exterior wall of a building, referenced in Sentence 3.1.5.7.(2) from the application of Sentence 3.1.5.6.(1). The change essentially clarifies that the CAN/ULC-S134 test is not required when the FAP is tested in conformance with Sentence 3.1.5.7.(2) (CAN/ULC-S101, “remain in place”). This further clarifies that if a factory assembled panel does not meet the criteria in Sentence 3.1.5.7.(2), then the code user must default back to the more restrictive Article 3.1.5.6. If the criteria in Article 3.1.5.6. is not met, then the code user must default back to the more restrictive Article 3.1.5.1. and the material must be noncombustible.
NRC Proposed Change to Article 3.1.5.15. is below. This change proposes to provide an exemption for a FAP containing foamed plastic referenced in Sentence 3.1.5.7.(1) from the application of Sentence 3.1.5.15.(2) which would otherwise require the foamed plastic to be protected by a thermal barrier. Unfortunately, the change does not go far enough to exempt other FAPs from the application of this Sentence. For example, a walk-in cooler or freezer referenced in Sentence 3.1.5.7.(3) is still subject to Sentence 3.1.5.15.(2) and is required to be protected by a thermal barrier, because this Sentence has not been included in the exemptions listed in Sentence 3.1.5.15.(2). It is my opinion that it is not the intent of the code to require a thermal barrier to protect coolers and freezers containing foamed plastic. A similar argument is also applied to Sentence 3.1.5.7.(2).
Can This Get Any More Complicated?
To make matters even more confusing, there are products on the Canadian market containing generation II polyisocyanurate foamed plastic that are achieving incredible results when tested to CAN/ULC-S101.
- What if the FAP passes the CAN/ULC-S134 test described in Article 3.1.5.6. and the CAN/ULC-S101 test in Article 3.1.5.15?
- Can these FAPs be used on tall buildings and Group A, B & C occupancies?
- Can a FAP be used as a fire separation if the FAP passes the required CAN/ULC-S101 test in conformance with Article 3.1.7.1.?
- Can a FAP containing foamed plastic be used as a thermal barrier to protect other foamed plastic products?
Although Codes Canada and the Canadian Commission on Building and Fire Codes appear to acknowledge the editorial issues surrounding factory assembled panels, more work is required to ensure the grammar and editorial connections between Articles within Subsection 3.1.5. of the code are consistent and easily interpreted by code users. The publication of the 2020 National Building Code of Canada has been delayed until December of 2021.
Interpretation of AHJs
Through my experience, I have found that the permitted use of a factory assembled panels containing foamed plastic without a thermal barrier, such as walk-in coolers and freezers, has been widely accepted. The current 2015 National Building Code may require otherwise. What do you think?
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