CSA Tested Assemblies Draft 2
CSA Tested Assemblies Draft 2
1 Specified Wind Loads and User Responsibility
Before you use these tables, know the wind load requirements for the roof under design or construction. You can find guidance in Part 3 SECURING the ROOF ASSEMBLY of the membrane system that is specified. Specified Wind Loads for the three principal roof zones may be calculated either by using the formulae in the British Columbia Building Code, 4.1.7 Wind Loads, or by using the National Research Council's online tool, Wind-RCI online wind calculator.
The tables on this page display a collection of test data and downloadable reports offered for the purpose of designing and constructing a roof capable of resisting negative wind pressures, commonly referred to as "wind uplift" loads. The data and reports are offered without endorsement by the RCABC; they are provided as a courtesy by the RoofStar Guarantee Program to assist the Design Authority with the task of designing a roof that satisfies Code requirements, that meets the designer's specific and numerous design preferences, and that will qualify for a RoofStar Guarantee.
The British Columbia Building Code (or the Code having jurisdiction) requires a roof to be capable of resisting Specified Wind Loads (see the British Columbia Building Code, Part 4 (4.1.7 Wind Loads) and Part 5 (5.2.2.2 Determination of Wind Load), inclusive of the notes in the appendices). The reader will note that there are optional pathways by which a membrane roof design can comply with the Code. One pathway is the use of a "Tested Assembly" - a roof assembly tested in controlled laboratory conditions to resist simulated wind pressures and gusts. The test must be conducted in strict conformity to CSA-A123.21 Standard test method for the dynamic wind uplift resistance of membrane roofing systems (CSA-A123.21). The results of the test are published in a report signed off by the accredited testing agency. Each report details the materials and securement methods of the assembly. Every detail in a Tested Assembly report is critical for the performance of a roof designed on the basis of the tested assembly.
CSA-A123.21 classifies assembly tests by the method of securement, and these are simplified with three acronyms:
- AARS (Adhesive Applied Roof Systems)
- PARS (Partially Adhered Roof Systems)
- MARS (Mechanically Attached Roof Systems).
For a fuller explanation of these three classifications, see Part 3 SECURING the ROOF ASSEMBLY of the membrane system that is specified.
CSA-A123.21 requires that the published test limits for a roof system be adjusted by dividing the final test value by a safety factor of 1.5. This factor reduces the actual test results in order to account for variables that a laboratory cannot test for, such as strong wind gusts or sudden wind shifts. The tables displayed in the tabs to the right show only the adjusted Dynamic Uplift Resistance (DUR) values and can be validated by reviewing the downloadable test reports.
It is imperative that the user of these reports become familiar with the structure and content typical in a Tested Assembly report. While you will see that each accredited testing agency publishes test results in their own preferred format, there is general consistency among the report styles in the type of data each report provides:
- a designation of the securement system (AARS, PARS or MARS), although some reports do not do this and the classification of the test can be determined only by reading the report
- the DUR (most reports make this explicit at or near the top of the report although there are some reports that provide the DUR within the report text)
- a list of tested and alternate materials
- how each material was secured, and
- the size of fasteners or the types of adhesive used.
All of these variables, and more, affect the performance of the roof assembly. Care must therefore be taken to collect and analyze all this information in relation to the limitations of the building and the roof, and all these details (for example, the specific name of the adhesive and how it was applied) must be included in the design specifications that will ultimately guide the construction of the roof.
2 CSA-A123.21 and Tested Assembly Reports
The CSA-A123.21 Standard test method for the dynamic wind uplift resistance of membrane roofing systems (CSA-A123.21) is, properly speaking, a test for membrane roof systems where the membrane is exposed to the weather. Consequently, you will not find Tested Assembly reports that apply to Protected Membrane Roof Assemblies (where the membrane lies beneath the constituent components of a roof assembly). To secure PMRAs, refer to Part 3 of the membrane system that is specified.
A few roof systems were tested without insulation. Most of these were tested on a plywood deck, but some were tested on steel. Because these assemblies are listed together with reports for insulated roofs (also referred to as compact or conventional), the reader should always look beyond the DUR and read the test report in order to understand the entire assembly.
3 Tested Assemblies and RoofStar Guarantee Standards
Tested Assembly reports must always be read together with the RoofStar Guarantee Standards for the membrane system that is specified. For example, a roof assembly might be tested with a particular material or in a particular way that does not conform to the Standards. To conform to our Standards, some modifications to the Tested Assembly may be required, which may then preclude its use - for example, adding an insulation overlay panel where none was tested, because the assembly design requires one in order to conform to the RoofStar Guarantee Standards.
When a conflict is apparent or obvious the Design Authority may find a way to 'yes' by examining the alternative materials listed in many Tested Assembly reports. Alternatives include membranes, insulation overlays, insulation panels and roof deck overlays (commonly listed as "thermal layers"). Some materials are listed as "optional" which means that while the assembly was tested without the constituent material (a deck overlay, for example), the Design Authority may opt to use one of the materials listed in the report. Drop-down menus of the tables below (see the "View options" buttons) display Accepted Materials that can be used in each Tested Assembly.
If in doubt about how to use the Tested Assembly reports together with the RoofStar Guarantee Standards, contact the RoofStar Guarantee Program via email, or by calling (604) 882-9734.
4 Accepted Materials and Material Substitutions
We have selected Tested Assembly reports based on the membranes that will qualify for a RoofStar Guarantee Program, but there are tested assemblies that include one or more Secondary Materials that are not Accepted by the RoofStar Guarantee Program. Drop-down lists clearly show this by indicating when a material is "not accepted". To ensure that the entire roof system complies with the Accepted Material requirements of the RoofStar Guarantee Program, follow the requirements in 3.2.1 Material Substitutions in Tested Assemblies:
- "When a manufacturer's Tested Assembly incorporates materials (and listed alternates) that are not part of the RoofStar Guarantee Program, the Design Authority must identify appropriate substitutions for those materials from the list of RoofStar-accepted Materials and consult the manufacturer concerning compatibility with the Tested Assembly. and direct the user to consult the membrane manufacturer in order to determine which Accepted materials will qualify as alternates."
© RCABC 2020
No reproduction of these Standards, in whole or in part, is lawful without the expressed permission of the RGC Guarantee Program.