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CSA A123.22-08 (2013): Specifications and Compliance for Asphalt-Coated Glass-Fibre Base Sheets
A Comprehensive Guide to the Canadian Standard for Roofing Base Sheet Materials
Scope and Purpose
CSA A123.22-08 (2013) establishes the material and performance criteria for asphalt-coated glass-fibre base sheets intended for use in built-up roofing (BUR) and modified bitumen roofing systems. This standard, reaffirmed in 2013, applies to base sheets that may be manufactured with or without a fine mineral surfacing, sanded backing, or a factory-applied adhesive layer (e.g., self-seal strips).
The primary purpose of this standard is to ensure that base sheets provide a dimensionally stable, tear-resistant substrate that can withstand the stresses of roofing installation and service environments across Canada’s diverse climate zones. It harmonizes with related CSA A123 series standards for cap sheets and vapour retarders, ensuring system compatibility.
Compliance Note: Products certified to CSA A123.22-08 (2013) are recognised by the National Building Code of Canada (NBCC) and most provincial building codes for use in prescribed roof assemblies.
Technical Requirements
Material Composition
The base sheet consists of a nonwoven glass-fibre mat impregnated and coated with an oxidised or polymer-modified asphalt. The glass-fibre mat provides tensile strength and dimensional stability, while the asphalt coating ensures waterproof integrity. Optional surfacing (e.g., sand, mica, or granules) may be applied for slip resistance or ultraviolet protection during short-term exposure.
Physical Properties
To meet the standard, base sheets must satisfy the following property requirements when tested according to the referenced ASTM or CSA methods:
| Property | Requirement | Test Method |
|---|---|---|
| Mass per unit area (overall) | ≥ 1.90 kg/m2 | ASTM D146 |
| Thickness | ≥ 1.0 mm | ASTM D374 |
| Tensile strength (machine direction / cross direction) | ≥ 290 N / 200 N (minimum average) | ASTM D828 |
| Tear resistance (machine direction / cross direction) | ≥ 200 N / 150 N | ASTM D4073 (modified) |
| Pliability (4°C, 1″ mandrel) | No cracking or delamination | ASTM D146 |
| Dimensional stability (80°C, 1 h) | ≤ 0.5% shrinkage or expansion | ASTM D4798 |
| Asphalt softening point (for coating) | 85–110°C (ring-and-ball) | ASTM D36 |
All tests are performed on samples conditioned at standard laboratory conditions (23 ± 2°C, 50 ± 5% relative humidity) for at least 24 hours prior to testing. The manufacturer must provide evidence of sampling frequency and quality control procedures that maintain these properties.
Important: Asphalt coating composition affects compatibility with adjacent membranes. Always verify that the base sheet’s coating is compatible with the cap sheet or torch-grade membrane to avoid interlayer adhesion failures.
Implementation and Installation Highlights
Substrate Preparation
The substrate must be clean, dry, and free of debris, ice, or standing water. For nailable decks, fasteners must be corrosion-resistant and spaced according to the base sheet manufacturer’s approved installation instructions. For concrete or steel decks, mechanical attachment or full adhesion with mopping-grade asphalt is typical.
Overlap and Seaming
Side laps and end laps must meet the minimum coverage specified (usually 75–100 mm for side laps and 150–200 mm for end laps). For self-adhered versions, the release film must be removed just before membrane placement, and the lap areas must be roll-pressed to ensure intimate contact.
Tip: In cold weather (below 5°C), self-adhered base sheets may require warm storage or an infrared heater to activate the adhesive. Follow manufacturer’s low-temperature application guidelines.
Fastener Pattern and Loads
For mechanically attached systems, the fastener pattern must be determined based on wind load calculations per NBCC. Typically, fasteners are spaced 300 mm on centre along the sheet edges and 600 mm in the field. The standard does not prescribe a specific pattern but requires that the base sheet resist uplift forces without fastener pull-through.
Compliance and Quality Assurance
Third-Party Certification
Most jurisdictions require that base sheets be certified by a recognised third-party agency such as CSA Group, Underwriters Laboratories (Canada), or Intertek. Certification ensures ongoing quality control through periodic audits and witness testing of production samples. The certification mark on the packaging confirms that the product conforms to CSA A123.22-08 (2013).
Health & Safety Alert: Hot asphalt application and torch-application of modified bitumen involve high temperatures and flammable materials. Always use personal protective equipment (PPE) and follow workplace safety regulations during installation.
Quality Control Testing
Manufacturers must document in-plant testing results for each production lot. At a minimum, mass per unit area and tensile strength are monitored continuously, while tear resistance and dimensional stability are checked at intervals not exceeding 40,000 m2 of product. Annual verification of all physical properties is required for continued certification.
Packaging and Labeling
Each roll must be labelled with the manufacturer’s name, product type, roll weight, roll area, production lot number, and the CSA A123.22-08 (2013) designation. The label must also indicate if the sheet is intended for mechanical attachment, full adhesion, or self-adhered application.
Q: Is CSA A123.22-08 (2013) equivalent to any ASTM standard?
A: While CSA A123.22-08 (2013) is specific to Canadian conditions, it is closely aligned with ASTM D4869-20 (Standard Specification for Asphalt-Saturated Organic Felt Used in Roofing and Waterproofing) but uses glass-fibre mat instead of organic felt. Some property requirements are similar, but temperature grading and dimensional stability tests differ for the Canadian climate.
A: While CSA A123.22-08 (2013) is specific to Canadian conditions, it is closely aligned with ASTM D4869-20 (Standard Specification for Asphalt-Saturated Organic Felt Used in Roofing and Waterproofing) but uses glass-fibre mat instead of organic felt. Some property requirements are similar, but temperature grading and dimensional stability tests differ for the Canadian climate.
Q: Can CSA A123.22-08 (2013) base sheets be used as a vapour retarder?
A: Generally, no. Base sheets are designed primarily for structural stability and waterproofing layers in a roof assembly. If a vapour retarder is required, refer to CSA A123.26 (Vapour Retarders for Roofing) for appropriate products, which may be installed below the base sheet.
A: Generally, no. Base sheets are designed primarily for structural stability and waterproofing layers in a roof assembly. If a vapour retarder is required, refer to CSA A123.26 (Vapour Retarders for Roofing) for appropriate products, which may be installed below the base sheet.
Q: What is the typical service temperature range for a roof system using CSA A123.22-08 (2013) base sheets?
A: The base sheets themselves can withstand service temperatures from -40°C up to 90°C, provided the correct asphalt grade is used. The system’s temperature limits are generally dictated by the cap sheet or surface material; always consult the roof assembly designer for specific thermal performance requirements.
A: The base sheets themselves can withstand service temperatures from -40°C up to 90°C, provided the correct asphalt grade is used. The system’s temperature limits are generally dictated by the cap sheet or surface material; always consult the roof assembly designer for specific thermal performance requirements.
This article is intended for informational purposes. For full regulatory and technical details, refer to the current edition of CSA A123.22-08 (2013) published by CSA Group.
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