Tag Archives: Field testing

To Test or Not to Test…? A guide to field quality control

Photo © BigStockPhoto/Vichaya Kiatying-Angsulee

Photo © BigStockPhoto/Vichaya Kiatying-Angsulee

by Sean M. O’Brien, PE, LEED AP, and David Artigas, PE

When properly implemented, field and laboratory testing of buildings and their systems and components can yield a wealth of useful information about construction quality, watertightness, durability, longevity, and other critical performance criteria.

Test results can help designers better evaluate ‘as-built conditions,’ understand any problems with the installation, and develop solutions appropriate to the specific problems that prompted the testing. When improperly implemented, however, testing can yield misleading results, lead designers to incorrect conclusions, and cause unnecessary expenses related to remedial work that may not really be warranted by the in-situ conditions.

In some cases, specifying inappropriate standards or performance criteria can create confusion or incite debate between the design and construction teams, especially in the event of a perceived failure. This article reviews some of the common test methods and procedures used in contemporary construction, with a focus on how the purpose of, and results from, these tests are often misunderstood.

This site-built interior chamber creates differential pressure across a curtain wall system for a test under American Architectural Manufacturers Association (AAMA) 503, Voluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls, and Sloped Glazing Systems.

This site-built interior chamber creates differential pressure across a curtain wall system for a test under American Architectural Manufacturers Association (AAMA) 503, Voluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls, and Sloped Glazing Systems. Images courtesy Simpson Gumpertz & Heger

The spray rack above has been positioned on the window exterior for AAMA 502, Voluntary Specification for Field Testing of Newly Installed Fenestration Products.

The spray rack above has been positioned on the window exterior for AAMA 502, Voluntary Specification for Field Testing of Newly Installed Fenestration Products.

 

 

 

 

 

 

 

 

 

 

 

Most important (but least asked) question
With dozens of industry organizations publishing thousands of test standards for buildings and building systems, there is almost always a quick answer to the questions: “What do I test and how do I test it?” However, the more important question, and one about which designers and contractors are often less sure, is “Why do I test?”

The answer to this question will almost always dictate the best method to use, the timing of the test, the pass/fail criteria, and sometimes whether it should be performed at all. In the case of poorly specified tests, the wrong tests are often performed ‘because it was in the specifications’ or ‘because the contractor owes us testing.’ Especially with fast-track construction projects, debates over testing are often brushed aside in favor of doing whatever the specification demands, regardless of the value of that testing.

In the authors’ experience, requiring designers to explain the reasoning behind their specified test methods or procedures can be an extremely useful exercise, either during the design process or as part of pre-construction activities. In the case of a designer having correctly specified test methods, the discussion can provide valuable information to the rest of the project team, giving everyone involved a better understanding of the reasons behind the testing. For improperly specified tests, the conversation can help avoid unnecessary testing and the resulting time/expense, as well as identify the correct test methods to determine the desired information.

Flood testing of a membrane waterproofing system on a rooftop parking deck occurs the finished paving is installed.

Flood testing of a membrane waterproofing system on a rooftop parking deck occurs the finished paving is installed.

Dye is used to color water during a roof flood test; it can help link interior leaks to specific areas of the roof above.

Dye is used to color water during a roof flood test; it can help link interior leaks to specific areas of the roof above.

Windows, doors, and curtain walls
Some of the most commonly tested building components are fenestration products—windows, doors, and curtain walls. For new construction, testing is most often specified as a quality control measure to ensure the installed system(s) meet the specified performance requirements for air and water penetration resistance.

The most common requirements are for testing in accordance with various American Architectural Manufacturers Association (AAMA) standards, depending on the system being evaluated. This requires the designer or specifier to know what type of system is specified as well as the relevant performance requirements to establish the appropriate test method.

There are different standards for different components, and some contain multiple test methods or options. For example, AAMA 501.1, Standard Test Method for Water Penetration of Windows, Curtain Walls, and Doors Using Dynamic Pressure, includes a method to test curtain fenestration for water penetration under dynamic wind pressure that requires a large fan—essentially, an airplane engine/propeller—and calibrated spray racks. There is also AAMA 501.2, Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls, and Sloped Glazing Systems, which is much easier to perform as it uses a simple handheld nozzle to spray along gaskets and joints. In this case, specifying testing per AAMA 501 is insufficient—the specific test method from that standard needs to be called out, as the two options vary greatly in scope and complexity.

In previous versions of the AAMA 501 standard, a third option (501.3) was available to perform water leakage testing under static pressure differential (Figure 1). Despite this test being pulled from the standard and replaced by AAMA 503-02, Voluntary Specification for Field Testing of Newly Installed Storefronts, Curtain Walls, and Sloped Glazing Systems, references to the 501.3 method can still be found in specifications written today. This often results in confusion when the time comes to perform the tests.

AAMA 501.2 is intended as a field check for water leakage—a simple, economical method to verify the general quality of the curtain wall installation. For compliance with a specified level of air- and water-penetration resistance, AAMA 503 must be used. It is important to note 501.2 is solely intended for fixed glazing systems; the high nozzle pressure used would likely cause moderate to severe leakage on operable vents or window products due to the inherent limitations of seals and gaskets used in operable fenestration.

For testing window assemblies (both fixed and operable) for compliance with a specified air- and water-penetration, AAMA 502, Voluntary Specification for Field Testing of Newly Installed Fenestration Products, is typically specified. This involves building a chamber on the interior of the product to allow for negative interior air pressure and using a spray rack to wet the exterior of the window (Figure 2).

It is important to understand this test method has a specific definition of what constitutes a leak. For example, water on the sill members that does not pass the innermost projection of the window is not considered a leak, since it does not reach a point where it can damage interior finishes. This can come as a surprise to designers witnessing the test and seeing water on the sill, only to find out that by the standard’s strict definition, the window is considered to not have leaked. For this reason, some specifiers add their own language regarding the definition of leakage, but may have difficulty holding a manufacturer to this definition in the event of a dispute.

It is also important for designers to clearly specify the pass/fail criteria for windows. This information can be derived from the performance class (e.g. R, CW, or AW) and grade for the product being tested, but is often misinterpreted, leading to confusion during the test or attempts to hold installers/manufacturers to unrealistic or non-industry-standard performance criteria.

Another caveat of AAMA 502 (since the 2008 revision) as well as AAMA 503 is they only apply to newly installed fenestration products. The standards define ‘new’ as products installed before issuance of the certificate of occupancy for the building or products that have been installed for less than six months.

This recent development is often a source of debate, as this means a window installed for six months and one day, even in an unoccupied/incomplete building, is no longer subject to AAMA 502 and therefore cannot be tested for compliance with the manufacturer’s stated performance criteria. In simpler terms, the manufacturer of the window is only held to its stated performance criteria for six months. For older products, AAMA 511, Voluntary Guideline for Forensic Water Penetration Testing of Fenestration Products, contains diagnostic procedures for identifying known leaks, but is not specifically intended to evaluate in-situ performance of non-leaking windows.

When specifying testing, it is important to make the distinction between test specifications, standard test methods, and testing guides. Each of these types of documents is used for a different, but often similar, purpose. Standard test methods, such as ASTM E1105, Standard Test Method for Field Determination of Water Penetration of Installed Exterior Windows, Skylights, Doors, and Curtain Walls, by Uniform or Cyclic Static Air Pressure Difference, contains specific information on how to physically test these various components, what equipment to use, and related information.

Test specifications, such as AAMA 502, provide procedural information on the testing, the relevance/applicability of the testing, and related administrative information, and typically reference standard test methods (e.g. ASTM E1105) for the physical test procedures.

Finally, testing guides, such as ASTM E2128, Standard Guide for Evaluating Water Leakage of Building Walls, are usually more general in nature and cover a wide range of components and procedures rather than focus on one specific area of the building enclosure. Similar to test specifications, these guides include procedural/administrative requirements and reference standard test methods for the actual testing procedures. Due to their non-specific nature, including ‘compliance’ with a testing guide such as ASTM E2128 as a specification requirement is likely to result in confusion, as it can be interpreted in many ways for many different components. A testing specification and pass/fail criteria must be clearly identified in the contract documents.

This depicts laboratory testing of brick masonry for compressive strength.

This depicts laboratory testing of brick masonry for compressive strength.

Water leakage through brick veneer/cavity wall can be seen from the interior through openings in the backup wall. The veneer does not provide actual waterproofing for this assembly due to presence of drainage plane and weather-resistant barriers.

Water leakage through brick veneer/cavity wall can be seen from the interior through openings in the backup wall. The veneer does not provide actual waterproofing for this assembly due to presence of drainage plane and weather-resistant barriers.

Roofing assemblies
Leakage from roofing systems, especially in the case of low-slope assemblies, can result in significant interior damage when left unchecked. There are many different methods for testing roofs, but not all are compatible with all assembly types. Understanding which methods can be used for which systems is key to specifying the appropriate test, whether as part of a specification for quality control in new installations or as part of remedial/troubleshooting efforts.

In this article, the authors focus on large-scale testing of roof areas, as opposed to smaller-scale testing of specific detail conditions (which is most often done using spray racks/nozzles or localized flood testing). As discussed, the roof’s configuration, as well as the specific membrane type, must be considered when specifying a test method.

The most obvious method of testing a roof—flooding it with water—can be effective in some cases, but extremely damaging in others. Flood-testing is best-suited to inverted roof membrane assemblies (IRMAs) where the membrane is installed directly over the structural deck, with insulation and ballast or other overburden above. In those cases, the testing is performed once the membrane and flashings are complete but prior to the installation of any overburden (Figure 3).

For this test, which is standardized in ASTM D5957, Standard Guide for Flood Testing Horizontal Waterproofing Installations, water is ponded over the system for a period of 24 to 72 hours, during which time the interior is reviewed for leaks. The depth of water must be reviewed to ensure the structural capacity of the roof is not exceeded, as every inch of water adds approximately 0.24 kPa (5 psf) of load. This can be challenging on large or complex roofs, where the deck slope may require compartmentalizing the test into smaller areas. Any leaks resulting from this test are likely to produce only localized damage which gets repaired along with the leaking component(s).

This test procedure is not appropriate for traditional ‘membrane-over-insulation’ roof systems, since leakage through the membrane may wet (and necessitate the replacement of) large areas of roof insulation. Especially in the case of a concrete roof deck, leakage through the membrane could go unnoticed or travel far from the original location as the deck retains the water, allowing large areas of insulation to become damaged and making it difficult to determine the leak’s source. These risks can be reduced by flooding only small areas at a time (limiting the amount of water that could enter the roof), in which case the water can be dyed to provide confirmation of leak sources if multiple areas are flooded in sequence (Figure 4).

There are several test methods available for traditional insulated roofing systems that do not carry the same risk of large-scale damage. These methods typically rely on specialized equipment to detect wet insulation below the membrane. Infrared (IR) thermography uses an infrared camera that visualizes temperature differences on surfaces by measuring and processing emitted radiation.

For an insulated roof, wet insulation will tend to retain more heat and cool slower than dry insulation. Since moisture from roof leaks is often trapped in the system for an extended period, scanning of a roof with suspected or known leaks shortly after the sun has set can help identify areas of wet insulation.

The IR camera measures the surface temperature of the membrane, so this method cannot be used on ballasted roofs since the ballast (e.g. gravel) will cool off uniformly and mask any small temperature differences on the membrane below. Similarly, testing on a windy day may yield misleading results as airflow over the membrane surface may even out temperature differences or cause the wet areas to cool off to the same temperature as the surroundings before the scan is made.

IR scanning of a roof is relatively efficient since large roof areas can be surveyed relatively quickly (some companies even offer aerial surveys, which can be economical for very large, open roof areas). A second method, often referred to as electrical capacitance/impedance (EC) testing, uses handheld or rolling (push-cart) equipment that sends electrical pulses into the roof system and measures the insulation’s ability to retain electrical charge. Wet areas will tend to hold a charge for less time than dry, allowing for relative comparison between areas. Similar to infrared, this method requires an exposed roof membrane since the scanner needs to be in close proximity to the insulation to be effective. For this method to be effective, the roof membrane needs to be non-conductive, making it ineffective on most ethylene propylene diene monomer (EPDM) assemblies or on membranes with metallized reflective coatings. For both of these methods, secondary verification (i.e. roof probes) of suspected wet materials should always be specified to confirm the efficacy of the test for the specific application.

A more recently developed test method uses specialized equipment to pinpoint specific defects in the membrane. In this method, a potential difference is created between the wetted roof surface and the grounded roof deck. Any breaches in the membrane create, in effect, a short circuit in the system which can be detected using specialized equipment.

This method can be used on both traditional and IRMA systems, but—similar to EC testing—the roof membrane must be nonconductive for the method to work. For new construction, especially on traditional roof systems, a grounding screen can be added below the membrane or cover board to provide more positive leak detection and become part of a permanently installed leak detection system. This type of system can be especially beneficial for vegetated roofing assemblies where the often significant amount of overburden can make locating leakage sites extremely difficult.

This infrared image shows air leakage around a window perimeter during a whole-building test.

This infrared image shows air leakage around a window perimeter during a whole-building test.

Brick masonry and exterior walls
Brick masonry has been a common building material in the United States since the colonial period, and mass masonry walls continued to be built through the first half of the 20th century. While the basic process of brick manufacturing has not changed much, modern technology allows the creation of brick typically much stronger and has greater uniformity of properties than historic brick. Historic lime mortars typically are softer and more permeable than modern cement mortars, which allows them to absorb greater stress within the wall from expansion and contraction or enables the wall greater capacity to ‘breathe.’

Concerns with historic masonry fall under two, often related, headings: the masonry’s structural capacity and durability. While it certainly is true modern masonry manufactured and constructed to meet modern standards should result in durable construction, it is not always necessary to hold historic masonry to these same modern standards, as the historic materials often have more than the necessary capacity to provide a long service life with good performance. Also, certain properties being lesser than modern standards may prove beneficial to performance.

The International Building Code (IBC) now has requirements for masonry properties such as compressive strength and performance in shear, though that was not always the case. Current codes are written for current construction, and do not always include previsions for how historic construction ‘works’ structurally. The International Existing Building Code (IEBC) includes provisions that allow historic buildings to remain, or repairs to occur, using original or like materials, but the structural engineer and code officials must still evaluate the structure’s capacity to withstand its loads and remain safe.

Structural engineers can use both non-destructive and destructive methods to determine masonry’s strength and ability to withstand stresses (Figure 5). It is important to specify testing appropriate to both the structure being evaluated and the goal of the evaluation. While a historic mass masonry wall may not meet the letter of the current code requirements, it may have capacity that exceeds its in-service loads with an acceptable factor of safety comparable to the code. That said, one concern with mass unreinforced masonry is it typically does not perform well during seismic events. In areas of higher seismic activity, greater care must be exercised in its evaluation.

Current requirements for energy efficiency mandate the building enclosure to have a specified resistance to heat transfer. While mass masonry walls typically have a lower R-value than modern insulated wall assemblies, they have an advantage—their bulk provides thermal mass unmatched by newer assemblies comprising several thinner layers of different materials sandwiched together. This thermal mass allows the wall to absorb and dissipate heat more slowly than modern walls, slowing the interior of the building’s reaction to changes in the exterior temperature and reducing the need for supplemental heating or cooling.

Changes to the thermal properties of a mass masonry wall, such as adding insulation to the interior, or significantly increasing the interior moisture load, may affect brick performance. Uninsulated historic masonry typically allows moisture to move through the wall (i.e. ‘breathe’) while remaining above the dewpoint, since the interior heat warms the wall.

The addition of interior insulation will reduce the wall’s temperature during the colder months. Water absorbed by the brick’s exterior wythe may go through freeze-thaw cycling as a result of the wall now being colder, and interior moisture that migrates through the wall assembly may condense on the inboard side of the masonry wall, because this side of the wall now is on the ‘cold side’ of the insulation.

Historic masonry may have two advantages that will reduce the likelihood of these two events occurring.

1. Historic brick typically is more porous than modern brick. This greater porosity may allow the brick to ‘drain’ rainwater more quickly than modern brick, and the larger pores may allow the absorbed water more room to expand without causing damage.
2. Historic lime mortars are more absorptive and permeable than modern mortars, and these properties may allow the mortar to wick water rather than having it remain on the wall.

However, it must be stressed the reaction of mass masonry to the installation of interior insulation is still a topic of study among engineers and preservationists. Further, there are currently no established guidelines for insulating walls, only various opinions on the matter.

Many designers of renovation projects may equate strength with durability and specify masonry testing with this thought in mind. Great care must be exercised when considering insulating mass masonry walls, and testing of the masonry’s porosity, absorption, permeability, expansion, and relative strength (both of brick and of mortar) should be performed. Additionally, laboratory testing and evaluation to determine the relative durability of the brick, as well as its resistance to freeze-thaw damage, are a crucial part of this kind of study.

It is also critical to evaluate test results in light of numerous factors, such as the type of building/occupancy, building use, and general quality of the surrounding construction. If a sampling of brick test as SW grade (suitable for severe weathering per ASTM C216, Standard Specification for Facing Brick [Solid Masonry Units Made from Clay or Shale]) that does not necessarily mean the wall assembly in question has the level of durability required for the specific application. SW brick on a large, clear wall area will likely provide suitable performance, but the same brick installed in a shaded location (i.e. minimal drying) below a window that experiences leakage (i.e. excessive wetting) may undergo premature degradation regardless of the brick grading.

The most important question to ask when evaluating a historic masonry building is: “How has it performed thus far?” If the building shows no obvious signs of distress after several decades or even centuries of use, its testing and evaluation must begin from a position of “How does it work?” as opposed to one of “Does it meet the code requirements for modern construction?”

This understanding will include site observations and possibly onsite or laboratory testing, and research into historic construction methods and materials. Ultimately, this approach to evaluating historic masonry may lead to a more efficient and lower cost project that also can maintain the building’s character. Regardless of testing, designers who take this approach much understand when the use of the building or other characteristics of the enclosure are changed as part of renovations, the prior performance of the building may not be a suitable predictor of long-term durability.

From a water penetration standpoint, there are many different test methods available for masonry walls, but not all provide useful information. For example, ASTM C1601, Standard Test Method for Field Determination of Water Penetration of Masonry Wall Surfaces, determines water penetration at the surface of a masonry wall, but does not provide any information on how much water actually leaks to the interior (as opposed to water that is absorbed and stored by the masonry). Similarly, RILEM tubes can be used to provide relatively quick evaluations of the water absorption rate of a masonry wall.1

ASTM E514, Standard Test Method for Water Penetration and Leakage Through Masonry, provides for measurement of the actual amount of water penetrating the full thickness of the masonry, but this is a lab test not applicable to field conditions (although it is often specified—incorrectly—by designers evaluating existing masonry buildings). Field surface absorption tests may have limited use in qualitatively evaluating the change in absorption that results from installing a penetrating sealer, but are typically of little to no use in evaluating water leakage.

Neither of these tests will be of practical value for masonry cavity wall construction, where any water penetrating the exterior façade is collected in a drainage cavity and wept out of the system (Figure 6). Water leakage through a masonry cavity wall is more likely the result of a breach in the water-resistive barrier (WRB) behind the masonry, since masonry veneer systems are expected to allow water into the drainage cavity.

The authors have generally found the general guidelines from ASTM E2128, Standard Guide for Evaluating Water Leakage of Building Walls—as opposed to one specific standard test method—are helpful in establishing the right combination of testing and inspection to diagnose water leakage through masonry walls.

Air barrier systems
As far as building testing goes, the testing of air barrier systems is a relatively recent development.2 Just as with window and curtain wall testing, there are multiple test standards and guides for testing air barrier systems in both the lab and the field. One of the first points of confusion is the definition of an air barrier—a system of interconnected components including walls, windows, curtain walls, and roofs that act together to prevent uncontrolled airflow into and out of the building. While air barrier testing is often thought of as testing a wall air barrier membrane (one component of the system), it can encompass everything from single materials to the entire building enclosure.

Some of the most commonly tested building components are fenestration products like windows and curtain walls. For new construction, testing is most often specifi ed as a quality control measure to ensure the installed systems meet the specifi ed requirements for air and water penetration resistance. Photo © BigStockPhoto/Graça Victoria

Some of the most commonly tested building components are fenestration products like windows and curtain walls. For new construction, testing is most often specified as a quality control measure to ensure the installed systems meet the specified requirements for air and water penetration resistance. Photo © BigStockPhoto/Graça Victoria

Testing of actual materials, such as sheet- and fluid-applied membranes, is performed in the laboratory due to the very small quantity of air leakage being measured and the high degree of accuracy required in the measurement. Air barrier products are required by most codes to allow no more than 0.02 L/s.m2 @ 75 Pa (0.004 cfm/sf at a pressure differential of 0.3 in. of water). In reality, most sheet membranes (such as self-adhered rubberized asphalt products) exceed this criteria by an order of magnitude or greater—much too low to be reliably measured in the field.

Air barrier assemblies—essentially, air barrier materials in an as-built condition that includes laps, seams, and penetrations—can be tested in either the lab or the field. Laboratory testing per ASTM E2357, Standard Test Method for Determining Air Leakage of Air Barrier Assemblies, provides an air leakage rate for a pre-defined arrangement of air barrier products, penetrations, and a window opening (but not the window itself—an oft-overlooked element of the air barrier system).

While primarily a laboratory test used by air barrier manufacturers to demonstrate their products’ performance and code compliance, the method can also be applied to field-installed mockups. However, applying this test in the field is not as simple as installing a chamber on the interior and testing the exterior. Air leakage through the perimeter of a sample area (e.g. through a concrete block or stud wall perpendicular to the interior-exterior direction) is often impossible to isolate, and due to the relatively low leakage rates being measured, even a small amount of extraneous leakage can create a false negative test result. Using this general chamber testing approach on a qualitative basis is simpler and often more effective, since telling a contractor that the test result was 0.25 L/s.m2 (0.05 cfm/sf)—in other words, a failure—does not provide the same level of usefulness as telling them there were leaks at one membrane seam and two brick ties that need to be repaired.

Specifications for field-installed air barrier assemblies often include testing of the window as part of the assembly. While this makes sense from a practical standpoint (i.e. the connection to the actual window system is a critical transition in the air barrier), there are limitations to this test. From a practical standpoint, mockup testing of air barrier assemblies typically happens at the beginning of a project, often long before the windows are delivered to the site (or in some cases, before specific window products are even selected). Testing of the assembly with a ‘dummy window’ in place is possible, but results can be misleading since the actual connection is unlikely to be the same as what is intended for the project windows.

In cases where the dummy window is put in temporarily with sealants and sprayed-applied foam insulation, the actual leakage rate may be much lower than what will occur when the project windows are installed, giving a false positive result for the test. In the case of the project windows being available at the time of testing, the specification of pass/fail criteria for the air barrier assembly test becomes more important. The performance criteria for air barrier assemblies are based on a window perimeter being included, but not the window itself. Since most windows will experience significantly higher leakage (on an area basis) than air barrier materials and assemblies, leakage through the window may far exceed the air barrier assembly leakage criteria, even if the assembly itself, minus the window, would pass on its own. For this reason, it is important to clearly specify how and if the window is to be included in the test, and, if so, some increase in allowable air leakage needs to be included to avoid requiring a result which is not attainable in the field.

The third type of air barrier testing is whole-building testing, using blower door or similar equipment and ASTM E779, Standard Test Method for Determining Air Leakage Rate by Fan Pressurization, procedures to measure overall air leakage through the entire building—including all walls, roofs, and windows. Different codes and standards require different overall leakage rates, but 0.02 L/s.m2 @ 75 Pa (0.4 cfm/sf at 0.3 in. of water) is typical for most building and energy codes.

While this test provides a single number to describe air leakage that can be easily compared to other buildings, it has many limitations that must be considered before requiring a certain level of whole-building performance. The first major issue is at the time when the air barrier is substantially complete to the point where testing can be performed, it is also likely to be concealed by cladding and other materials that can make the detection (using IR thermography or tracer smoke) and repair difficult or impossible.

Second, the testing itself can be difficult to perform, especially on large/more complex buildings, due to the need for multiple fan systems that must all be linked together for measurement or adjustment. In tall buildings, internal fans may be needed to equalize pressure differentials over the height of the building. While most testing firms can easily come to a site and perform standard window or curtain wall tests, large-scale testing of whole buildings requires specialized equipment and a fair degree of experience and expertise to successfully execute.

Lastly, there is some debate over what is achievable in terms of air leakage through whole buildings. A designer can certainly specify the overall leakage rate needs to be 0.5 L/s.m2 (0.1 cfm/sf), but achieving that level of airtightness requires an exceptionally well-designed air barrier, as well as carefully planned execution of the construction.

This is a common mistake with all types of air barrier testing—specifying a high level of airtightness without providing the corresponding design detailing is a futile effort. As mentioned, once the building is physically ready to be tested, it is often far too late to practically implement repairs, which brings up the difficult question of “What do we do now that we failed the test?” While the industry is still working on answering that question, specifiers can help avoid problems by specifying reasonable levels of airtightness appropriate for the building design.

As with the other previously described tests, visualization techniques such as infrared thermography and tracer smoke can be used to take advantage of the pressure differential created during a whole building test and qualitatively identify air leakage sites (Figure 7).

Conclusion
While the wide variety of available testing standards means there is almost always a standard for the designer’s specific need, finding the right standard can be difficult when one does not have a firm understanding of the actual goals. Designers and specifiers should first evaluate the question of ‘why’ when it comes to testing, as the answer will typically guide them to the correct test method to follow.

Specifying both the appropriate testing method and the appropriate pass/fail criteria are necessary to provide meaningful test results and avoid the time and expense of unnecessary testing or inappropriate testing which leads to ambiguous results. A little more time spent researching test methods during the design phase and specifying appropriate methods and performance criteria can go a long way toward reducing confusion and disputes during the construction process in the field.

Notes
1 For more on RILEM tubes, see The Construction Specifier articles, “Testing the Test: Water Absorption with RILEM Tubes,” by Adrian Gerard Saldanha and Doris E. Eichburg, and “Durable Waterproofing for Concrete Masonry Walls: Redundancy Required,” by Robert M. Chamra and Beth Anne Feero in the August 2013 and July 2014 issues. (back to top)
2 For more on air barriers, see the article “Wind Load and Air Barrier Performance Levels,” by Maria Spinu, Ben Meyer, and Andrew Miles, in the July 2014 issue. (back to top)

Sean M. O’Brien, PE, LEED AP, is an associate principal at the national engineering firm Simpson Gumpertz & Heger (SGH), specializing in building science and building enclosure design and analysis. He is involved in both investigation/forensic and new design projects. O’Brien is a member of the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE), co-chair of the New York City Building Enclosure Council (BEC-NY), and a frequent speaker and author on topics ranging from building enclosure design to energy efficiency. He can be reached at smobrien@sgh.com.

David Artigas, PE, is senior staff I–building technology at SGH, specializing in building enclosure design and investigation, building science, and historic preservation. He can be reached at djartigas@sgh.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.