Tag Archives: Curtain wall

More great walls of fire: Exterior separations

by Jeff Razwick

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A fire-rated curtain wall provides lot line protection in a dense city. All images courtesy TGP

As shown in this author’s previous article, fire-rated walls typically stand guard inside buildings, ready to compartmentalize fires from within at any moment. As urban density and demand for daylight and visibility in the building envelope increase, these assemblies are also proving valuable for a growing number of exterior applications.

Fire-rated curtain walls can prevent a fire from traveling to or from neighboring buildings without restricting visibility. Unlike gypsum, masonry, and other opaque fire-rated materials, this multi-functionality can bring fire and life safety goals in line with the aesthetic design intent where building codes deem the threat of fire is significant from adjacent construction.

For design professionals evaluating when to use the assembly in the building envelope, it can be helpful to look at situations where it can benefit exterior separations with fire safety requirements.

Property line protection
As it becomes more efficient to build upward and closer together in cities to accommodate growing populations, property line setbacks are narrowing. This is generating an increase in the number of buildings required to use fire-rated materials as exterior separations—a safeguard building codes typically only require for structures in close proximity to each other.

Generally, lot line protection is required when a building is close to its neighbor, regardless of whether that adjacent structure is on the same lot. To provide clarity on this requirement, building codes specify the horizontal separation distances requiring fire-rated materials. For example, see International Building Code (IBC) Sections 705.5 and 705.8. In Section 705.3, IBC uses an imaginary line to determine whether buildings on the same piece of property are in close proximity to each other.

Where codes deem it is necessary to protect against the spread of fire between buildings, fire-rated curtain walls make it possible to do so while maintaining visibility and light. For example, they can provide lot line protection without sacrificing light transfer. Well-designed fire-rated curtain walls can even extend the surface area through which light can transfer to help illuminate a building’s core and better support green building goals. Some fire-rated curtain walls are available with fire-rated insulated glass units (IGUs) incorporating tinted or low-emissivity (low-e) glass for more efficient solar energy management, while taking advantage of daylighting techniques.

Transparent fire protection
Opaque fire-rated materials like gypsum and masonry can satisfy property line requirements and provide compartmentalization for both exterior and interior spaces. The downside is they restrict light transfer and visibility. Fire-rated glass curtain walls can serve as a clear alternative given their heat blocking characteristics; specifically, their classification as fire-resistance-rated wall construction.

Fire-rated curtain walls are tested to ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials, and Underwriters Laboratories (UL) 263, Fire-resistance Ratings. Receiving classification as non-directional fire-resistance-rated construction (meaning they can maintain the same fire-rating from both sides) rather than an “opening protective,” they can exceed 25 percent of the total wall area to provide transparency from the outside where fire and life safety is a concern.

Exterior cladding performance criteria
The air and water penetration resistance of fire-rated steel curtain wall systems (tested per ASTM E283, Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure, at 30.47 kgf/m2 [6.24 psf] and per ASTM E331, Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform Static Air Pressure Difference, at 20 percent of design wind load, respectively) is typically better than comparable, non-rated aluminum systems. The steel profiles are protected from air and water penetration by a continuous, full-width silicone gasket mounted to the face of the profiles in the glazing pocket.

Regarding thermal performance, the increased thickness of the rated glass in fire-rated curtain walls can help reduce potential for heat flow. Where energy-efficient curtain wall design is critical to building goals, fire-rated IGU constructions allowing low-e glass to be incorporated in the ‘glass sandwich’ can further improve energy performance. As an added benefit, narrow steel frames paired with high-performance fire-rated glazing can help lower the potential for heat transfer and therefore increase condensation resistance. Simulations of the actual construction can be modeled, giving the designer the ability to know how the fire-rated curtain wall will affect the sizing of the building’s HVAC systems.

Fire-rated curtain walls with steel frames can also work in close conjunction with surrounding materials to help ensure a sound building envelope as the temperature changes. Steel’s coefficient of expansion is nearly half that of aluminum, and is similar to glass and concrete. This also reduces the size of perimeter sealant joints, especially at locations where expansion is being addressed.

Tested to ASTM E119 and UL 263, fire-rated curtain walls can provide fire protection from the outside in.

Tested to ASTM E119 and UL 263, fire-rated curtain walls can provide fire protection from the outside in.

Support for demanding applications
Industry standards for exterior curtain wall frames typically limit deflection due to wind load to L/175 or 19 mm (¾ in.)—whichever is less—for spans under 4 m (13 ½ ft), and L/240 for greater spans (where L equals the length of the span between anchor points). These standards were originally developed to prevent sealant failure of insulating glass units due to mullion deflection.

In fire-rated curtain walls, the rated glass may impose stricter limits on the framing, such as L/300. Since steel has a Modulus of Elasticity three times that of aluminum, it can more easily meet these deflection limits without increasing the system profile size. It can also reduce the need to reinforce the frame members. As a best practice, one should consider verifying deflection requirements with the glass manufacturer before accepting typical industry standards.

Conclusion
For all the ways fire-rated glass can enhance building design goals for interior fire separations, there is an almost equal amount of options to do the same for exterior fire-rated glazing applications. To ensure the safety of people and property while still providing a high-performance product required by specification for exterior applications, it is important aesthetic goals align with fire and life safety standards in local building codes. Where necessary, the design team can consult with the manufacturer or supplier.

Jeff Razwick Head ShotJeff Razwick is the president of Technical Glass Products (TGP), a supplier of fire-rated glass and framing systems, and other specialty architectural glazing. He writes frequently about the design and specification of glazing for institutional and commercial buildings. Razwick is a past-chair of the Glass Association of North America’s (GANA) Fire-Rated Glazing Council (FRGC). He can be contacted via e-mail at jeffr@fireglass.com.

 

Great walls of fire: Interior separations

by Jeff Razwick

Fire-rated curtain walls can satisfy life safety requirements without sacrificing transparency. All images courtesy TGP

Fire-rated curtain walls can satisfy life safety requirements without sacrificing transparency. All images courtesy TGP

Glazed curtain walls are best known for their ability to visually integrate two otherwise separate spaces. Less talked about—though, perhaps more important—are curtain walls with the capability to retain visibility and access to daylight while standing guard against fire.

Tested to ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials, and Underwriters Laboratories (UL) 263, Fire-resistance Ratings, fire-rated curtain walls can satisfy life safety requirements without sacrificing transparency—for better safety and aesthetics. Their multi-functionality is critical to helping design teams meet a complex set of performance criteria with one product, eliminating redundant systems and streamlining construction.

Simply put—fire-rated curtain walls allow design teams to do more with less in areas where fire and life safety is a concern. For design professionals interested in using the tough-yet-transparent form of such curtain walls to tackle multiple project demands for interiors, certain questions may arise during the specification process.

1. What constitutes a fire-rated curtain wall?
Fire-rated curtain walls block the transfer of flames and smoke, as well as radiant and conductive heat, for the duration of their given fire rating. To achieve this level of defense, fire-rated curtain walls incorporate fire-resistive glass and framing.

Fire-resistive glass is typically a clear, multi-laminate product with an intumescent interlayer that turns opaque during a fire. This reaction allows the glass to carry fire ratings up to 120 minutes, pass the fire and hose stream tests, and remain relatively cool on the non-fire side of the glass for its designated fire rating.

Fire-resistive frames serve as the support structure in fire-rated curtain walls, and can block the transfer of radiant and conductive heat for up to 120 minutes. While many framing systems employ fire-resistive insulating materials to achieve the necessary defense, those using inherently heat-resistant framing materials like carbon steel do not typically require thermal barriers within their core to protect against heat transfer. Regardless of the material chosen, packing the perimeter of the framing system to the rough opening with firestop insulation or an appropriately rated intumescent sealant is critical to the system’s overall performance.

Some manufacturers offer comprehensive fire-rated curtain wall systems, complete with frames, glass, seals, and component parts. These integrated assemblies ensure all components are designed and tested in the same assembly and to the same standard. This is critical since the International Building Code (IBC) requires all elements within a fire-resistive glazing assembly to provide the same category of fire resistance and carry the minimum fire rating as stated in the code.

Fire-rated frames can be wet-painted or powder-coated to match virtually any color scheme.

Fire-rated frames can be wet-painted or powder-coated to match virtually any color scheme.

2. Where are fire-rated glass curtain walls suitable for use?
Fire-rated curtain walls are typically suitable wherever building codes require an assembly designated “fire resistant” to enclose a space. Examples include wall applications requiring a 60-minute or greater fire rating that must meet temperature-rise criteria, such as stairwells, walls in exit corridors, or other fire barriers dividing interior construction exceeding 25 percent of the total wall area.

Since the choice to incorporate fire-rated curtain walls is often at the design team’s discretion, it is important to evaluate whether the daylight and visibility provided is advantageous to occupant safety and well-being. For example, an expansive multi-story, fire-rated curtain wall may prove beneficial to people working in a hard-to-light office. Similarly, a single-story fire-rated curtain wall enclosing a stairwell, lobby, or gathering area can extend line of sight to boost safety levels or create a sense of collaboration.

3. Are fire-rated glass curtain walls suitable in areas where they are susceptible to impact?
Fire-rated curtain walls are available with glazing that provides up to Category II (Consumer Product Safety Commission [CPSC] 16 Code of Federal Regulations [CFR] 1201, Safety Standard for Architectural Glazing) impact-safety ratings. This is the highest rating, indicating the glass can safely withstand an impact similar to that of a fast-moving adult. As such, fire-rated curtain walls are ideal for use in high-traffic areas, including schools, gymnasiums, and hospitals.

4. How do fire-rated and non-fire-rated curtain walls compare?
Unlike the bulky, wraparound form of traditional hollow metal steel frames, modern fire-rated frames have a slender profile and sleek aesthetic. They can be much narrower, have well-defined edges (rather than rounded profiles), and have vertical-to-horizontal framing joints without visible weld beads or fasteners.

In areas where a frame-free exterior surface is desirable, it is now possible to specify fire-rated curtain walls with the smooth, monolithic appearance of a structural silicone glazed system. One available assembly is silicone-sealed and requires no pressure plates or caps. Its toggle retention system becomes completely hidden once installed, creating a seamless, uninterrupted surface appearance.

5. What finishes are available for fire-rated curtain wall systems?
Design professionals can achieve nearly any look when it comes to fire-rated frame appearance. Carbon steel frames can be wet-painted or powder-coated to match virtually any color scheme, from aluminum to bright greens and blues. Framing materials also include polished or brushed stainless steel.

Fire-rated frames are also available with finished stainless steel or aluminum custom cover-caps to provide design professionals with even greater aesthetic flexibility. The face caps are available in numerous shapes and sizes—from H- and I-shapes to custom configurations. Stainless caps are typically brushed finish while aluminum ones can be wet-painted, anodized, or powder-coated to match the framing.

Modern fire-rated frames have a slender profile and sleek aesthetic to improve sightlines and views between spaces.

Modern fire-rated frames have a slender profile and sleek aesthetic to improve sightlines and views between spaces.

6. Are there any limitations to be aware of?
Since mismatched fire-rated glass and framing ratings can jeopardize the safety of a fire-rated curtain wall, it is important to verify the entire assembly provides the same type of fire protection and has a fire rating equal to or greater than the code requires. This includes the glass, frames, hardware, and all component parts.

From a performance standpoint, use of fire-rated glass requires stiffer deflection limits due to imposed wind loads. Typical curtain walls will allow L/175 (where L = span of the framing member between anchor points) or 19 mm (3/4 in.), whichever is less. Due to the nature of the fire-rated glass, deflection is limited to L/300. This may not be critical for interior applications where the only wind load is from mechanical systems, but it becomes important when designing fire-rated curtain walls for exterior applications.

Regarding installation, it is helpful to keep in mind many frames in fire-rated glass curtain walls are shipped as knock-down (K-D) kits ready for onsite assembly. While frame components may be pre-assembled or welded in the factory, pre-assembly is often done on a case-by-case basis. If pre-assembly is critical to a job’s timeframe, one should verify the manufacturer has the resources to assist with this process.

Conclusion
While one of the primary advantages of selecting a fire-rated glass curtain wall system is the ability to do more with less, aesthetic goals should never come at the cost of safety. Manufacturers and suppliers are available to help problem solve or create a custom work-around to balance life safety with design goals.

Jeff Razwick Head ShotJeff Razwick is the president of Technical Glass Products (TGP), a supplier of fire-rated glass and framing systems, and other specialty architectural glazing. He writes frequently about the design and specification of glazing for institutional and commercial buildings. Razwick is a past-chair of the Glass Association of North America’s (GANA) Fire-Rated Glazing Council (FRGC). He can be contacted via e-mail at jeffr@fireglass.com.

 

Testing Glazing in the Field: Performance Classes

Up until the 2008 edition of American Architectural Manufacturers Association/Window and Door Manufacturers Association/Canadian Standards Association (AAMA/WDMA/CSA) 101/I.S.2/A440, North American Fenestration Standard/Specification for Windows, Doors, and Skylights (NAFS), there were five performances classes of windows with differing requirements for test pressures, allowed leakage rates, and other variables. The current four types, and their minimum performance grades are:

  • R ([15 psf]);
  • LC ([25 psf]);
  • CW ([30 psf]); and
  • AW ([40 psf]).

Water

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penetration resistance test pressure (for laboratories) is 15 percent of the performance grade for R, LC, and CW classes; 20 percent for the AW Class.

To read the full article, click here.

Testing Glazing in the Field: Specifying procedures now avoids trouble later

Photo © Bruce Damonte. Photo courtesy Wausau

Photo © Bruce Damonte. Photo courtesy Wausau

by Dean Lewis

Water penetration through the building envelope is a serious concern, involving issues ranging from what constitutes reasonable performance during a hurricane to resolving liability for interior water damage and possible toxic reactions to moisture-induced mold. Fenestration is the prime candidate for being the weakest link in the weather-resistant barrier, and thus typically receives the greatest scrutiny.

However, faulty fenestration design is not likely to be the cause of leakage problems. Products that meet the appropriate Performance Class and Grade defined by the code-mandated American Architectural Manufacturers Association/Window and Door Manufacturers Association/Canadian Standards Association (AAMA/WDMA/CSA) 101/I.S.2/A440, North American Fenestration Standard/Specification for Windows, Doors, and Skylights (NAFS), must pass laboratory water leakage spray tests of increasing stringency, depending on the applicable onsite Design Pressure (DP) as based on the wind speed contour maps of American Society of Civil Engineers/Structural Engineering Institute (ASCE/SEI) 7-10, Minimum Design Loads for Buildings and Other Structures.

These laboratory tests simulate wind-driven rain according to ASTM E547, Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Cyclic Static Air Pressure Difference, and ASTM E331, Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform Static Air Pressure Difference, by simultaneously applying air pressure at 15 percent of DP for all window classes, except the AW Class, for which it is 20 percent. (For more, see “Performance Classes.”)

Field testing of a storefront system to American Architectural Manufacturers Association (AAMA) 503, Voluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls, and Sloped Glazing Systems. An exterior pressure chamber establishes the pressure differential, and a calibrated spray-rack is located inside the chamber. Photos courtesy AAMA

Field testing of a storefront system to American Architectural Manufacturers Association (AAMA) 503, Voluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls, and Sloped Glazing Systems. An exterior pressure chamber establishes the pressure differential, and a calibrated spray-rack is located inside the chamber. Photos courtesy AAMA

These are not trivial conditions. For example, a 290-Pa (6.0-psf) water test pressure (WTP) is equal to that exerted by an 80-km/h (50-mph) wind. Such pressure develops an equivalent hydrostatic water head of 30 mm (1.2 in.), which may be enough to force water over a windowsill and into a building.

Yet, there are limitations on the extent to which even this rigorous testing can predict performance in the field. Water leakage may occur during a heavy rainstorm because the wind velocity pressure exceeds that for which the water penetration resistance of the window or door was designed and tested.

Additionally, laboratory tests cannot account for water penetration that actually may originate from the surrounding wall or roofing construction, causing water to run down the wall’s inside surface. Most importantly, lab tests do not account for window leakage due to improper installation, which—because building construction is rarely perfect—is the more likely culprit.

Product samples tested in the laboratory are positioned perfectly plumb, level, square, and true within a precision test fixture opening. In the field, although installed within acceptable industry tolerances, products are unlikely to find such exacting conditions. Shipping, handling, acts of subsequent trades, aging, and other environmental conditions all may have an adverse effect on product performance as installed when compared to the test results.

Specifiers are advised to require verification of the actual installed performance of fenestration products by insisting on field testing during or immediately after construction and before occupancy.

AAMA provides four field testing methods:1

  • AAMA 501.2, Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls, and Sloped Glazing Systems, which should be used as a spot-check during construction of a curtain wall or storefront system;
  • AAMA 502, Voluntary Specification for Field Testing of Newly Installed Fenestration Products, which is the proper test method for verifying field air leakage and water penetration resistance of newly installed operable windows and doors;
  • AAMA 503, Voluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls, and Sloped Glazing Systems, which is the proper test method for field testing of new storefronts, curtain walls and sloped glazing for air leakage resistance and water penetration resistance; and
  • AAMA 511, Voluntary Guideline for Forensic Water Penetration Testing of Fenestration Products, which is intended for performing a systematic forensic investigation of observed, known leaks.

AAMA 501.2
Intended to be used during the construction process, AAMA 501.2 is inappropriate for testing operable windows and doors. It neither simulates the effects of wind-driven rain nor provides quantitative performance information. Rather, it is a simple, economical water spray quality check to reveal leaks in non-operable glazing, including gaskets, sealant, perimeter caulking, splices, and frame intersections.

Architectural skylights can also be field tested using AAMA methods.

Architectural skylights can also be field tested using AAMA methods.

The designated test area is divided into 1.52-m (5-ft) sections of the framing and joint. The area selected must include typical, representative samples of each part of the construction—usually a minimum of 9.3 m2 (100 sf), with no outstanding punch list items or other visible defects.

The test is conducted using a hose (19-mm [¾-in.] diameter suggested) and a special nozzle as specified in the standard. The water pressure to the nozzle must be 205 to 240 kPa (30 to 35 psi), unless a lower pressure is unavoidable, such as at a multistory building, but not lower than 172 Pa (25 psi). The nozzle is held at a distance of 305 mm (12 in.) from the location under test. Each section is evaluated for five minutes by slowly moving the nozzle back and forth over the test section. If leakage occurs, modifications are made and the test is repeated.

AAMA 502
The correct field test for air leakage and water penetration of newly installed fenestration units is AAMA 502. Testing is to be conducted before issuance of the building occupancy permit, but in no case later than six months after installation. It is based on ASTM E783, Standard Test Method for Field Measurement of Air Leakage Through Installed Exterior Windows and Doors, and ASTM E1105, Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Curtain Walls, and Doors by Uniform or Cyclic Static Air Pressure Difference.

To implement AAMA 502, a temporary test chamber is sealed to the interior (or, optionally, the exterior) side of representative fenestration products at appropriate stages of the product installation, subject to a minimum of three units. The test chamber is to be in such a manner as to apply the pressure differential to all joinery conditions with the wall. The number of products tested, and the frequency of testing, should be clearly specified by contract. (On large projects, tighter construction monitoring may be performed by testing at approximate intervals of five, 50, and 90 percent completion of the installation.)

Depending on whether installed on the interior or exterior, air is supplied to, or evacuated from, the test chamber at the rate necessary to establish and maintain the desired air pressure difference across the specimen. The maximum pressure needed is equal to two-thirds of the lab-tested and rated water test pressure as prescribed for the applicable product performance grade designation in NAFS, but not less than 91 Pa (1.9 psf).

For example, a product tested or rated as H-CW50 is field tested for water penetration resistance at a pressure differential of two-thirds of 360 Pa (7.5 psf), which equals 240 Pa (5 psf). This one-third reduction of the test pressure for field testing is considered to be a reasonable adjustment to account for the variables inherent in a field test environment.

Wind-driven rain from storms can account for moisture leakage into office tower curtain walls and windows. Photo © BigStockPhoto/Aleksey Fursov

Wind-driven rain from storms can account for moisture leakage into office tower curtain walls and windows. Photo © BigStockPhoto/Aleksey Fursov

Once the test pressure is established, a calibrated spray-rack applies water against the outside surface—with all operable portions of the specimen closed and locked—while technicians observe for any water penetration at the interior. ASTM E1105 Procedure A (uniform static air pressure difference; used for AW performance class windows) requires a 15-minute test with continuous pressure and water application. Procedure B (cyclic static air pressure difference; for all but the AW class) applies four water spray cycles of five minutes each under pressure, interspersed by one minute with the pressure released. To pass the test, there can be no penetration of uncontrolled water beyond a plane parallel to the product’s innermost edges.

AAMA 502 also provides for an air leakage resistance test, conducted per ASTM E783 at a minimum uniform static test pressure of 75 Pa (1.6 psf) except 300 Pa (6.2 psf) for the AW class; or as specified for the project, but not to exceed 300 Pa (6.2 psf). The acceptable air infiltration rate is limited to 2.3 L/s•m2 (0.45 cfm/sf) or 0.8 L/s•m2 (0.15 cfm/sf) for AW Class products. It is important to remember that air leakage is to be tested before the wall is wetted for water leakage testing—otherwise, water trapped within the wall components will tend to reduce air leakage.

AAMA 503
Similar to AAMA 502 but applicable to storefronts, curtain walls, and sloped glazing systems, AAMA 503 is also applied soon after the specimen is installed and sealants are cured, but before installation of gypsum wall board, insulation, or other finish materials, and no later than six months after issuance of the occupancy permit. Like AAMA 502, AAMA 503 bases its testing protocols on ASTM E1105 and E783.

AAMA 503 calls for testing to be conducted on at least a single 9.3-m2 (100-sf) area of installed product that is representative of the project.

Under AAMA 503, as with 502, the water penetration resistance test is performed per ASTM E1105’s Procedure A (uniform static air pressure difference), with the test pressure set at two-thirds of the specified project water penetration test pressure, but not less than 200 Pa (4.18 psf). In the event the project does not have a specified water penetration test pressure, the default value is 20 percent of the positive design wind load times 0.667. Water leakage is defined as any water not contained in an area with provisions to drain it to the exterior or the collection on an interior horizontal framing member surface of more than 14 g (0.5 oz) of water in the 15-minute test.

While ASTM E783 is referenced by AAMA 503 for field air infiltration testing, and may be used to evaluate the installed air leakage of ‘punched opening’ curtain walls, storefronts, and sloped glazing, it is not recommended for a portion of continuous systems due to the complexity of compartmentalizing air chambers and cavities. It is impractical to install a chamber on a segment of a continuous horizontal or vertical member.

If conducted, the air infiltration test proceeds at the same pressures called for in AAMA 502. However, the maximum allowable rates of measured air leakage must not exceed 1.5 times the project specification rate, or 0.45 L/s•m2 (0.09 cfm/sf)—whichever is greater. Or, the specifier may require project-specific air leakage.

This photo shows AAMA 503 field testing of an upper floor with the spray-rack supported by a telescoping boom. The air chamber under negative pressure is interior to the building. Photos courtesy AAMA

This photo shows AAMA 503 field testing of an upper floor with the spray-rack supported by a telescoping boom. The air chamber under negative pressure is interior to the building. Photos courtesy AAMA

Importance of early testing
Once it is installed, changes needed to repair a wall can be difficult and expensive. Thus, defining the acceptance criteria and field testing requirements in the project specification and performing the tests as soon as practical before a substantial portion of the project is completed (but no later than six months after installation) can help determine whether problems are present.

The advantage of testing prior to closing up interior walls and before building occupancy is design, fabrication, and installation problems can be revealed early enough that remedial work will be easier and less expensive.

Short-form specifications
AAMA 502 and 503 each provides a recommended short-form model specification that allows the specifier to prescribe the test pressures for both air infiltration and water resistance, depending on the location and wind exposure of the specific project as determined using the principles of ASCE/SEI 7. These are used by merely inserting the following paragraph(s), completed with the indicated information, into the project specifications.

AAMA 502 Short Form Field Testing Specification

  1. Newly installed fenestration product(s) shall be field tested in accordance with AAMA 502, Voluntary Specification for Field Testing of Newly Installed Fenestration Products.
  2. Test three (unless otherwise specified) of the fenestration product specimens after the products have been completely installed for air leakage resistance and water penetration resistance as specified.
  3. Air leakage resistance tests shall be conducted at a uniform static test pressure of ___ Pa (___ psf). The maximum allowable rate of air leakage shall not exceed ___ L/s•m2 (___ cfm/sf).
  4. Water penetration resistance tests shall be conducted at a static test pressure of ___Pa (____ psf). No water penetration shall occur as defined in AAMA 502.

AAMA 503 Short Form Field Testing Specification
The newly installed (storefront, curtain wall, and/or sloped glazing system) shall be field tested by an AAMA accredited independent laboratory, in accordance with AAMA 503, Voluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls and Sloped Glazing Systems. The area(s) to be tested is (are) as follows: [(exact description of the area(s) to be tested by referencing an architectural drawing that clearly shows the intent of the area to be field tested.)]

Any of the following optional paragraphs may be added to modify the standard AAMA 503 specification:

  1. Optional air leakage resistance tests shall be conducted at a uniform static test pressure of ___ Pa (___ psf). The maximum allowable rate of air leakage shall not exceed ___ L/s•m2 (___ cfm/sf).
  2. Water penetration tests shall be conducted at a static test pressure of Pa (psf).

The specifier may increase the field water test pressure to the value specified for the project. In the event the project does not have a specified water penetration test pressure, the value would be equal to 20 percent of the positive design wind load times 0.667.

AAMA 503 includes field testing for storefronts. Here, the interior air chamber is sealed to a representative section including at least one of each profile, intersection, and joint. The exterior calibrated spray rack is visible through the glass.

AAMA 503 includes field testing for storefronts. Here, the interior air chamber is sealed to a representative section including at least one of each profile, intersection, and joint. The exterior calibrated spray rack is visible through the glass.

Forensic investigation of existing fenestration
In addition to field testing before occupancy, situations may arise where a forensic investigation of an actual problem in an occupied building can pinpoint the leakage path by recreating the known water leaks. This is done by researching the actual weather events that produced the reported water penetration, using the procedures of AAMA 511. Unlike quality assurance (QA) field testing during or shortly after installation, forensic investigators are required to provide more information than pass/fail criteria.

AAMA 511 expands on the investigative process set forth in ASTM E2128, Standard Guide for Evaluating Water Leakage of Building Walls, which recommends a total of seven investigative, review, and preparatory steps prior to actual testing, as well as post-testing steps. Pretest inspection and data gathering include a review of project documents, design concept evaluation, and a review of service history and inspections—all aimed at developing a hypothesis for the water intrusion’s source.

The process begins by calculating the differential air pressures the suspect specimens experienced during the actual wind-driven rain conditions coinciding with the original leak. This calculated pressure defines the test pressure to which the fenestration product is subjected during the actual field testing. If this calculated wind pressure is greater than two-thirds of the rated WTP for the product, it may be the product was not the most appropriate selection for the project.

The investigative process then moves to actual testing—the protocol for which is similar to that of AAMA 502 or 503. An optional sill dam test, also described in AAMA 511, can be used as necessary to further investigate the leak path.

Some caveats
Generally, field testing accounts for the unavoidable fact that performance of installed exterior wall systems likely will be somewhat less than laboratory performance, due to accumulated manufacturing and installation tolerances. Built-in allowances accommodate this, as well as the difficulty that may be encountered in conducting field tests with the same precision as laboratory tests.

In many cases, investigators have used inappropriate field testing adaptations to AAMA 502 and AAMA 503 to investigate the reported water penetration. A common, incorrect adaptation involves performing water testing at a differential pressure higher than the pressure the fenestration product experienced during the wind-driven rain events that produced the water penetration. Field testing at these high pressures may result in new leaks and the false conclusion the fenestration product is the cause of all the reported water penetration. Field testing at elevated pressures also may conceal defects that would have produced leakage at lower pressures.

Determining which units to test is an important step when planning field testing. It is important the units chosen as the test specimens include typical perimeter and joint conditions that occur throughout the wall system between fixed glass, fixed panels, and the framing members.

The University of California at Berkeley’s (UC Berkeley’s) newly opened Energy Biosciences Building is the most energy-effi cient facility on campus, thanks in part to its windows. According to lead architect Johnny Wong of San Francisco-based SmithGroup JJR, the building was designed and constructed to meet Silver under the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) program. Photo © Bruce Damonte. Photo courtesy Wausau

The University of California at Berkeley’s (UC Berkeley’s) newly opened Energy Biosciences Building is the most energy-efficient facility on campus, thanks in part to its windows. According to lead architect Johnny Wong of San Francisco-based SmithGroup JJR, the building was designed and constructed to meet Silver under the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) program. Photo © Bruce Damonte. Photo courtesy Wausau

However, the quantity and location of the specimen(s) selected for AAMA 503 testing can markedly affect the cost of testing. ASTM E122-09e1, Standard Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot or Process, provides guidance on how to establish the number of test specimens required to measure the quality of a production lot with prescribed precision. Obviously, a situation where the cost of testing and building remediation approaches the cost of the glazing system should be avoided. Selecting as few as one specimen (or surface area as small as 9.3 m2 [100 sf] of glazing) may be sufficient to provide the information needed. On larger projects, a formal cost-benefit analysis is appropriate.

It is important to note AAMA 502, AAMA 503, and AAMA 511 all require the indicated testing to be performed by an AAMA-accredited testing laboratory—that is, one recognized as meeting the current requirements of AAMA 204, Guidelines for AAMA Accreditation of Independent Laboratories Performing On-site Testing of Fenestration Products. This ensures the laboratory has the qualified staff and calibrated equipment to properly perform field testing. One should be wary of any self-proclaimed window-tester, and ask to see the AAMA certificate of accreditation.

Finally, AAMA 501, Methods of Tests for Exterior Walls, is a good general reference that provides an overview of field testing. It places the individual protocols in context with one another, and also provides a comprehensive guide specification to cover all field testing protocols and options.

Notes
1 These and other AAMA documents may be obtained online from www.aamanet.org. (back to top)

Dean Lewis is the educational and technical information manager for the American Architectural Manufacturers Association (AAMA). He began his career in the fenestration industry at PPG Industries with positions in project engineering, product design, and sales and customer technical support, and has served on committees of American National Standards Institute (ANSI), ASTM, and the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE). Further experience includes teaching in the industrial and military sectors, and 35 years of managing technical training, publishing, and certification. Lewis has served on standards and certification committees of a dozen national and international organizations. He can be reached at dlewis@aamanet.org.

Meeting Efficiency Codes without Compromising Design: Technology that Meets Specifications

A full-scale mockup incorporating architectural insulation modules.  [CREDIT] Photo courtesy Dow Corning Corporation

A full-scale mockup incorporating architectural insulation modules. Photo courtesy Dow Corning Corporation

by Stanley Yee, LEED AP

To help overcome concerns about adoption of new technology, a full-scale mockup of a high thermally performing curtain wall incorporating architectural insulation modules was recently successfully tested by an independent third-party. Testing was conducted in accordance with American Architectural Manufacturers Association (AAMA) 501, Methods of Test for Exterior Walls, ensuring acceptable performance for air and water penetration resistance, structural capacity, and vertical and seismic movement requirements.

To read the full article, click here.