Essential knowledge for consistent fenestration specification

by arslan_ahmed | September 15, 2023 10:00 am

[1] By Steven Gille

In the world of fenestration, there is a wide variety of different products with a common purpose: to close the building envelope, allow light into the interior, and offer outside views. Fixed and operable windows, curtain wall, storefront, window wall, skylights, sliding doors, and hinged entrances are among the most familiar systems. Products must be evaluated to meet each project’s unique requirements and goals.

To ensure proper specification, it is essential to understand fenestration products are listed across multiple MasterFormat Divisions, and subject to different standards and code requirements.

Fenestration types are grouped into two broad product categories:

• Windows – The first category includes product types defined under the scope of AAMA/WDMA/CSA 101/1.S.2/A440 North American Fenestration Standard (NAFS), Specification for windows, doors, and skylights. NAFS has been referenced by the National Building Code of Canada (NBC) since its 2010 edition. The CAN/CSA Standard, A440-00/A440.1-00 (A3-B7-C5), is no longer recognized by the NBC and shall not be used in specifications (refer to Sidebar 2, page 2).
• Other Fenestration Assemblies – The second category includes curtain wall, storefront, and window wall, called “Other Fenestration Assemblies” as defined in the appendix of the current NBC 2020. These products are not covered by a specific testing protocol referenced in NBC 2020, but must achieve the performance minimums indicated for structure, water management, and air leakage.

Categorization and the relevant specifications become complicated when multiple fenestration products are selected for a single project, for example, when a NAFS scope window type is integrated into an “Other Fenestration Assemblies” product type, as defined in the NBC 2020 appendix. The specifications professional then must navigate a path through building and energy codes requirements, specific project needs, compliance with different standards and consistency between divisions, and expected quality and esthetics.

What is in the code?

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Canada’s 2020 National Model Codes are currently in effect. Code updates are now the responsibility of the newly formed Canadian Board for Harmonized Construction Codes (CBHCC). Proposed changes to the 2020 editions will be open for public review. If approved, code changes will be included in the 2025 editions of the National Model Codes, published by the National Research Council of Canada (NRC).

As per NBC 2020, Section 5.9.2. states that products listed in the scope of NAFS need to comply with both NAFS-17 and the CSA A440S1-19 Canadian Supplement to NAFS (refer to Sidebar 1 below) NAFS and the Canadian Supplement define the performance level and the process to determine it, the pass/fail criteria and tests protocols for structural considerations, and the air and water management.

Sidebar 1 – Standards, protocols, guides, and test methods noted in this article

Standards, protocols, guides, and tests methods noted in this article • AAMA/WDMA/CSA 101/1.S.2/A440-17 North American Fenestration Standard (NAFS), Specification for windows, doors, and skylights. • CSA A440S1-19 Canadian Supplement to AAMA/WDMA/CSA 101/I.S.2/A440-17, NAFS, Specification for windows, doors, and skylights. • AAMA 501-05, Methods of Test for Exterior Walls.* • AAMA 501.1-05, Standard Test Method for Water Penetration of Windows, Curtain Walls and Doors Using Dynamic Pressure.* • AAMA 501.2-09, Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls, and Sloped Glazing Systems.* • AAMA 501.4-09, Recommended Static Test Method for Evaluating Curtain Wall and Storefront Systems Subjected to Seismic and Wind-Induced Inter-Story Drifts.* • AAMA 501.5-07, Test Method for Thermal Cycling of Exterior Walls.* • AAMA 501.6-09, Recommended Dynamic Test Method for Determining the Seismic Drift Causing Glass Fallout from a Wall System.* • AAMA 910-10, Voluntary “Life Cycle” Specifications and Test Methods for AW Class Architectural Windows and Doors.* • AAMA 2604-13, Voluntary Specification, Performance Requirements and Test Procedures for High Performance Organic Coatings on Aluminum Extrusions and Panels (with Coil Coating Appendix).* • AAMA 2605-13, Voluntary Specification, Performance Requirements and Test Procedures for Superior Performing Organic Coatings on Aluminum Extrusions and Panels (with Coil Coating Appendix).* • AAMA 611-14, Voluntary Specification for Anodized Architectural Aluminum.* • ASTM E283-04, Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen. • ASTM E331-00, Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen. • ASTM E547-00, Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Cyclic Static Air Pressure Difference. • ASTM E330/330M-14, Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights and Curtain Walls by Uniform Static Air Pressure Difference. • ASTM E1748-95, Standard Test Method For Evaluating The Engagement Between Windows And Insect Screens As An Integral System. • CAN/CSA A440-00/A440.1-00, Windows/Special Publication; A440.1-00, User Selection Guide to CSA Standard; CAN/CSA-A440-00, Windows* – Do not use.Notes * Non-mandatory standards

 

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When it comes to Other Fenestration Assemblies, NBC 2020 Section 5.9.3. provides minimal requirements for air leakage tested at an air pressure difference of 75 Pa (1.57 psf) that is not greater than 0.2L/(s•m²) [0.30 cfm/sf] as per ASTM E283-04 (refer to Sidebar 3, page 4).

Water penetration compliance for NBC 2020 is achieved with either ASTM E331-00 or ASTM E547-00. The penetration resistance of the Other Fenestration Assemblies products must be capable of resisting driving rain pressure as determinate using the protocol and the climate design data defined in CSA A440S1-19.

ASTM E330/330M-14 is the acceptable protocol for structural and environment loads by reference in the NBC 2020 notes. Regarding loads, consult the NBC 2020 “Part 5 – Environmental Separation, Section 5.2 Loads and Procedures,” to review all loads affecting the Other Fenestration Assemblies due to a project’s specific conditions, location, and design. Even if these are not part of mandatory testing protocols, various loads can affect the fenestration components, and may require either project-specific testing or calculations.

Additional testing methods listed in the NBC 2020 notes include AAMA 501-05, AAMA 501.1-05, AAMA 501.4-09, AAMA 501.5-07, and AAMA 501.6-09 (refer to Sidebar 1 on previous page). These are not mandatory but offer helpful guidance for the specifications professional.

What is in NAFS?

NAFS and other standards have been updated since 2020. These updates may be reflected in proposed changes to the 2020 National Model Codes and, if accepted, could be included in the 2025 edition.

NAFS-17 applies to fixed and operable windows, and patio and terrace doors, which also can be integrated into Other Fenestration Assemblies products (refer to Sidebar 2 below). The purpose of NAFS is to evaluate windows products for comparable performances and to define performance levels. Aspects evaluated by NAFS include resistance to air leakage, water penetration, and structural environmental loads. In addition, evaluate for quality and durability through auxiliary testing such as operating force, ensuring ease of operation for occupants.

Minimal performance levels, relevant tests, and the test type depends on the product’s performance classes (PC). PC definitions describe a project’s typical characteristics and suggest differences in the testing protocols and the minimal dimensions required to undergo these tests as per NAFS.

Sidebar 2 – Fenestration product type deifinitions

• North American Fenestration Standard (NAFS) is for windows, doors, secondary storm products (SSPs), tubular daylight devices (TDDs), roof windows, and unit skylights. • Out of scope are interior products, garage doors, roof-mounted smoke, and heat-relief vents, sloped glazing, curtain walls, window wall, storefronts, commercial entrance systems, sunrooms, revolving doors, and commercial steel doors. • As per the National Building Code of Canada (NBC) 2020, “Other Fenestration Assemblies” includes curtain wall, window wall, storefront, and glazed architectural structures

 

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First, NAFS’ mandatory testing protocols involve measuring air leakage as per ASTM E283-04 at 75 Pa (1.57 psf). The result will be a measure of the volume of air going through the window at stable pressure differential per second and divided by the window surface area. Fixed products must meet the fixed level air leakage requirement of 0.2L/(s•m²) [0.04 cfm/sf], and operable products must minimally comply with the A2 level requirements of 1.5L/(s•m²) [0.30 cfm/sf]. The expression “air leakage” is used because both infiltration and exfiltration are tested since air can flow in both directions (refer to Sidebar 3 below).

Next, resistance to water penetration, validated in NAFS, follows ASTM E331-00 uniform static air pressure. Depending on the PC, the window specimen must resist water leakage at a defined minimal pressure of 15 per cent of the design pressure. Criteria to succeed this test differs in the U.S. and Canada. Be cautious when analyzing products to ensure the water penetration test complies with Canadian test requirements, namely that no water remains in an undrained fenestration framing cavity. However, water retained as droplets or surface film are not considered evidence of a failed test.

Finally, structural testing for NAFS references ASTM E330/330M-14, which involves two types of tests, each at a positive and negative static load.

• The first test validates how much a window will deflect under a specified design pressure. This does not validate for dangerous wind loads conditions, but it can demonstrate highly uncomfortable window movement for taller specimens. While all PCs are required to test for structural deflection, passing L/175 is only mandatory for commercial window (CW) and architectural window (AW) classes.
• The second tests the structural-ultimate wind load to 150 per cent of the static design load. All PCs must pass successfully to comply with NAFS. Operable products must remain locked during the test and operate after the test’s completion. This test helps ensure occupants egress safely.

Sidebar 3 – Air leakage requirements in codes

• Give special attention to fenestration products’ air leakage requirements. The National Building Code of Canada (NBC) 2020 and the National Energy Code of Canada for Buildings 2020 (NECB) do not have the same requirements for operable windows. • Fixed windows and Other Fenestration Assemblies must meet 0.2L/(s•m²) [0.04 cfm/sf] in both the NBC 2020 and NECB 2020. • For operable fenestration products, the requirement is 1.5 L/(s•m²) [0.30 cfm/sf] in the 2020 NBC, and 0.5 L/(s•m²) [0.10 cfm/sf] in the 2020 NECB. Remember, when a building is within the scope of a NECB, performances required in the NECB take precedence over those in the NBC.

In addition to these essential test protocols, NAFS describes minimal requirements to ensure products are easy to use, their screens remain in place on windy days, and they resist forced entry. This forced-entry test does not consider glass breakage type, but the product’s resistance to a quieter and less noticeable intrusion with the help of tools.

Products from all PC must also undergo the minimal mandatory tests. Their differences lie in the minimal dimensions of the tested samples, and the minimal water and wind load pressure they must meet. CW and AW classes are required to not exceed L/175 during the structural-deflection test. R and LC classes are tested to this, but the result does not determine a pass or fail.

In addition, AW class has more stringent requirements for air leakage with a maximum of 0.5L/(s•m²) [0.10 cfm/sf] for operable compression-sealed products and 0.2 L/(s•m²) [0.04 cfm/sf] for fixed products. Both are tested at 300 Pa (6.27 psf) for infiltration and 75 Pa (1.57 psf) for exfiltration. AW class products also must undergo two water tests: ASTM E331-00 uniform static air pressure and ASTM E547-00 cyclic static air pressure at a minimum of 20 per cent of the design pressure, defined with the structural-deflection wind load test.

The greatest distinction for AW class products is AAMA 910-10 life cycle testing. Life cycle testing involves thermal cycling from -18 C (0 F) to 82 C (180 F); opening, closing, and locking cycles of 4,000 operations each; and a misuse test for operable windows and doors. AW products must pass ASTM E283 air leakage and ASTM E331 water penetrations tests at the completion of cycling. The operating sash are then subjected to a torsion test.

AW class products also require high-performance finishes. Painted finishes must comply with AAMA 2604-13 or AAMA 2605-13, and Class I anodizing must meet AAMA 611-14 standards. This aspect should not be overlooked when preparing specifications (Figure 1).

The specified slider does not exist.

What is in the specification?

When it comes to specifying fenestration products, the most important consideration is to ensure consistency between requirements for products from Other Fenestration Assemblies, those in the scope of NAFS, and those in related divisions such as glazing and sealants.

First, regarding air leakage, it is important to validate requirements from both the NBC and the National Energy Code of Canada for Buildings 2020 (NEBC) and determine which one is applicable. Will the building be subject to continuous pressure differential because of the chimney effect, HVAC, or winds? These can be indicators for the air leakage rates and the pressure differential to specify.

Secondly, water resistance as per NBC 2020, driven rain pressure shall be determined using the climate design data and the protocol found in the CSA A440S1-19 Canadian Supplement to NAFS, as well as for Other Fenestration Assemblies.

The third and critical characteristic is structure. Does the project integrate tall or oversized fenestration products and does a deflection of more than L/175 present a concern to occupants or a risk for the glass?

Performance criteria expected of Other Fenestration Assemblies should be similar to those expected from windows integrated into these systems, or to adjoining windows in the same building. In addition to the air-water-structure trio, specification of extensive pre-construction testing may be needed for post-disaster buildings, super-tall buildings, or high-importance facilities. AW class can be an appropriate option for these situations since this PC requires additional, more stringent testing, and aligns with the Other Fenestration Assemblies’ AAMA 501 protocol (see Sidebar 3, page 3, and Sidebar 4 below).

If the project is a post-disaster building, a high-importance facility, or a highly customized design, the project-specific mock-up protocols, such as AAMA 501, may also be applied for fabrication, installation, and design validations. This approach offers the opportunity to identify and remediate potential issues during preconstruction, rather than facing costly changes on the actual building. However, no NAFS procedure specific to windows may be used for a product integrated into a mock-up that is following AAMA 501 protocols. If further job site validation is needed, AAMA suggests several protocols, but they are limited to water and air leakage because structural testing could compromise the integrity of the system or of the surroundings and are practically impossible outside of a test facility (see Sidebar 1, page 29).

Many building applications do not require extensive testing. What does a mid-rise, mixed-use complex, or a small commercial office demand of the Other Fenestrations Assemblies and windows forming its envelope? Examine NAFS and AAMA protocols to determine the actual performance needs for the project.

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Conclusion

Product performances obtained in the perfect world of a testing facility should only be specified to pre-qualify products. Those performances frequently surpass extreme environmental conditions. Products often do not perform the same as tested when installed on a project. Performance expectations should align with the real world as per climate design data and project-specific wind loads analysis, which already account for safety considerations.

Specifying too many test protocols or requesting job site compliance of air leakage and water penetration above realistic climate design data defined as per NBC, NEBC, and CSA A440S1-19 Canadian Supplement to NAFS can result in a significant loss of time and money with no real advantage to the project. Specifying few pre-construction test protocols and not verifying the products’ capability to fulfil their roles as per climate design data defined by codes, can also result in a significant loss of time and money. The risk of damages, forcing forensic evaluations and actions to correct the situation can be even more costly and time consuming.

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These well intended mistakes can be avoided by consulting with experts in the fenestration industry.

• Manufacturers can provide existing reports, offer guidance to align products’ performance with project needs, or develop a protocol for project-specific mock-up testing.
• Structural engineers can make calculations to validate the fenestration systems’ capacity to withstand loads at project-specific dimensions and can assist in determining the systems’ anchoring locations and methods. They also can review dynamic wind effects and assess how this may impact the building’s design and its surroundings.
• Consultants and testing teams can determine which protocols to use if mock-up or job site testing is required. They can advise when complex, oversized, or repeated fenestration may benefit from project-specific testing. They also can help define acceptable performance benchmarks for the project.

Finally, the specifier should be aware that fenestration tested to meet the highest standards still cannot guarantee the highest performance building. A project’s success goes beyond unquestioningly complying with a list of standards; thoughtful design, proper installation, and collaborative communication are essential.

[7]Author

Steven Gille is the pre-construction manager at Alumicor and Tubelite. He draws from more than 40 years of experience in designing, engineering, testing, and developing curtain wall, storefront, entrances, and daylight control systems. He works closely with specifiers, architects, glazing contractors, and consultants to assist with product information and selections, and new solutions. He can be reached at sgille@apog.com.

Source URL: https://www.constructioncanada.net/essential-knowledge-for-proper-fenestration-specification/

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