Proposed Change 1427

Sentence 9.25.4.2.(7) of Division B of the National Building Code of Canada (NBC) currently references CAN/CGSB-1.501-M89, "Method for Permeance of Coated Wallboard," for the testing of vapour barrier properties of coatings applied to gypsum board. Although CAN/CGSB-1.501-M89 is still applicable, it has not been updated since its initial publication in 1989 and was withdrawn by the Canadian General Standards Board (CGSB) in October 2011. As a result, manufacturers no longer test vapour barrier properties of coatings in accordance with CAN/CGSB-1.501-M89. Instead, manufacturers test vapour barrier properties of coatings in accordance with ASTM D1653-13, "Standard Test Methods for Water Vapor Transmission of Organic Coating Films," which is not currently referenced in the NBC. This creates enforcement issues for the authorities having jurisdiction (AHJs).

Justification

This proposed change would seek to resolve the enforcement issues noted above by replacing the reference to CAN/CGSB-1.501-M89 with a reference to ASTM D1653.

ASTM D1653

is equivalent to CAN/CGSB-1.501-M89,
represents the minimum Code requirements for testing the vapour barrier properties of coatings,
does not create any conflicts within the NBC,
does not modify any performance requirements in the NBC, and
will harmonize the Code with the state-of-the-art of the building envelope industry.

ASTM D1653 has a broader scope for the testing of vapour barrier properties of coatings as it applies to any material and is not limited to gypsum board as is the case with CAN/CGSB-1.501-M89. For this reason, this proposed change also revises Sentence 9.25.4.2.(7) to reflect the application of ASTM D1653 to any material and not just to gypsum board. This would allow for the introduction of new technologies onto the market.

In addition, this proposed change would add an explanatory Note to Sentence 9.25.4.2.(7) that would provide guidance for the application of fluid-applied vapour barrier coatings by referring Code users to the manufacturer’s specifications.

PROPOSED CHANGE

[9.13.2.2.] 9.13.2.2.Dampproofing Materials

[1] 1)Materials installed to provide required dampproofing shall be

[a] a)capable of protecting assemblies against moisture transfer from the ground,

[b] b)compatible with adjoining materials, and

[c] c)resistant to mechanisms of deterioration that may reasonably be expected, given the nature, function and exposure of the materials.

[2] 2)Except as otherwise specified in this Section, materials used for exterior dampproofing shall

[a] a)conform to one of the following standards:

[i] i)ASTM D1227/D1227M, "Standard Specification for Emulsified Asphalt Used as a Protective Coating for Roofing", Type III, Class I,

[ii] ii)ASTM D4479/D4479M, "Standard Specification for Asphalt Roof Coatings – Asbestos-Free", Type III,

[iii] iii)CAN/CGSB-51.34-M, "Vapour Barrier, Polyethylene Sheet for Use in Building Construction", or

[iv] iv)CAN/CSA-A123.4, "Asphalt for Constructing Built-Up Roof Coverings and Waterproofing Systems",or

[b] b)have a water vapour permeance of not more than 43 ng/(Pa×s×m²) when tested in accordance with ~~Procedure A (wet cup) of~~ ASTM E96/E96M, "Standard Test Methods for Water Vapor Transmission of Materials", using the water method (wet cup) and consist of one of the following material types:

[i] i)a vapour-resistant coating,

[ii] ii)a cold-fluid-applied or hot-rubberized bituminous dampproofing membrane,

[iii] iii)a liquid-applied or spray-applied asphalt-based emulsion dampproofing, or

[iv] iv)a type III hot-applied asphalt.

[9.25.4.2.] 9.25.4.2.Vapour Barrier Materials

[2] 2)Thermally insulated foundation wall assemblies are permitted to be constructed with variable-permeance vapour barriers having a permeance not greater than 60 ng/(Pa×s×m²) using the desiccant method (dry cup) and greater than 300 ng/(Pa×s×m²) using the water method (wet cup) measured in accordance with ASTM E96/E96M, "Standard Test Methods for Water Vapor Transmission of Materials".(See Note A-9.25.4.2.(2)PROPOSED CHANGE A-9.25.4.2.(2).)

[6] 6)Membrane-type vapour barriers other than polyethylene that are susceptible to deterioration under prolonged exposure to direct ultraviolet radiation shall

[a] a)be covered, or

[b] b)only be installed in locations that are not exposed to direct ultraviolet radiation after the completion of construction.

(See Note A-9.25.4.2.(6)PROPOSED CHANGE A-9.25.4.2.(6).)

[7] 7)Where a coating is applied to ~~gypsum board~~any materials to function as the vapour barrier, the permeance of the coating shall be determined in accordance with ~~CAN/CGSB-1.501-M, "Method for Permeance of Coated Wallboard".~~ASTM D1653, "Standard Test Methods for Water Vapor Transmission of Organic Coating Films," using the desiccant method (dry cup, Condition A). (See Note A-9.25.4.2.(7).)

Note A-9.25.4.2.(7) Application of Fluid-Applied Vapour Barriers.

The manufacturer’s specifications should always be consulted when using fluid-applied vapour barriers, to ensure a smooth, continuous film is applied and to avoid using too little or too much material, which could impact the vapour-retarding performance of the vapour barrier.

Impact analysis

No additional costs are expected to be incurred as a result of replacing the reference to CAN/CGSB-1.501-M89 with a reference to ASTM D1653. Currently, manufacturers already test coatings used as vapour barriers in accordance with ASTM D1653 and other materials used as vapour barriers in accordance with ASTM E96/E96M, which is currently referenced in the Code.

Enforcement implications

This proposed change can be enforced by the existing infrastructure without additional resources; however, training on the new standard is anticipated to be necessary for AHJs. This proposed change avoids enforcement issues for the AHJs.