the effect of changes of aama 502 standard

8/15/2019 The Effect Of Changes of AAMA 502 Standard

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INTRODUCTIONUncontrolled water penetration through

the building façade, exterior walls, andespecially fenestrations (windows) results inbillions of dollars of damage in the construction industry every year. Water penetration is of the utmost concern to buildingowners, the contractors and subcontractorswho construct the buildings, the architector engineer responsible for designing andspecifying the window products, and themanufacturers of the products. Manu facturers perform extensive “controlled” labtests in which windows are subjected tostructural loads, including wind force, aswell as water penetration tests usingnationally recognized test procedures.

Based on these test results, window anddoor units are assigned a performance rating by their respective industry organizations, such as the American ArchitecturalManufacturers Association (AAMA) and theNational Wood Window and Door Association (NWWDA). However, field water penetration tests must also be conducted totest the performance once the products areinstalled in buildings. The industry standards for field water penetration tests havecertain restrictions that must be understood by the design professional to ensurethat the window products installed withinthe exterior walls of a building meet theappropriate required code and industrystandard water penetration pressure. Recent changes in the test standard should becarefully reviewed to guarantee that theappropriate windows are designed, selected,installed, and properly tested in the field to

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resist water infiltration and avoid waterdamage to buildings.

WINDOW DESIGN

Selection of window units for residentialand commercial buildings begins with calculations by the project’s structural engineer or architect to estimate the designforce or pressure imposed by the wind. Theformulae used to perform these calculationsare found in ASCE 7, Minimum DesignLoads for Buildings and Other Structures.Chapter 6, Wind Loads, contains themethodology and formulae to estimate thewind-induced design pressure at threezones on the roof and two zones on theperimeter walls of the proposed building.

The applicable version of ASCE 7 and thewind speed to be applied at specific projectsare generally found in the building codeadopted by the local governing authority.

As an example, many cities have adopted the International Building Code (IBC)and the International Residential Code(IRC) for one- and two-family dwellings. Acity may also adopt local amendments toselected sections of the model codes. Thecity of Houston, for example, has stipulatedthat structural design shall be based onASCE 7-02, and the wind speed to be usedin the calculations shall be 110 mph (three-second gust). Other physical factors, suchas building dimensions, topography, andthe proximity of surrounding structures,are factored into the calculations to estimate the effective wind forces that willimpact the subject building.

These structural design loads are

reported as positive and negative loads andare commonly expressed in pounds persquare foot (psf). The positive load generallyoccurs on the windward side of the buildingand corresponds to the force of the windpushing against the walls, windows, anddoors. The negative load occurs at the leeward side of the building, where a vacuumis created at the downwind side by the windblowing past the building. The negative loadexerts a force that effectively attempts topull the cladding, windows, and doors offthe building. It is not uncommon for thevalue of the negative load to be differentfrom the value of the positive load. In anycase, the absolute value of the greatestwind-induced load, known as the designpressure, should form the basis for moststructural designs, water penetration requirements and, ultimately, window selections.

WINDOW SELECTION

The computed wind forces must be considered when selecting windows. Selectingwindows with a performance rating equal toor greater than a building’s highest positiveor negative design pressure as calculatedusing ASCE 7 ensures that the window unitwill resist the calculated wind forces andassociated water penetration requirements.When selecting a window, it is important forthe design professional to understand thedifferent performance classes and performance requirements and what informationthey provide. Windows are classified intofive performance classes: R – Residential,LC – Light Commercial; C – Commercial; HC

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Table 1 – Gateway requirements from AAMA/WDMA/CSA 101/I.S.2/A440-05, Standard Specification for Windows, Doors, and UnitSkylights.

– Heavy Commercial; and AW – Architectural Windows. Each performance classhas minimum gateway performancerequirements that the fenestration productmust achieve to be designated with a performance class ( Table 1). After the performance class, the window designation willhave a performance grade that is expressed

as the numeric equivalent to the designpressure in psf to which the specimen hasbeen tested. For example, a window with adesignation of HC50 would be a heavy commercial window with a performance grade of50 psf. This performance grade also equatesto a water-resistance test pressure thatmust be considered when selecting a prop

er window. Typically, AAMA equates thewater-resistance test pressure to 15% of thedesign pressure (varies between 15% and20%, based on the window unit’s performance class). As such, the performancegrade of the window designation should bereviewed when selecting the proper windowfor a project design load and water penetra

tion requirements.

WATER PENETRATION TESTING

In my experience, the single biggestclaim of “failure” for a window is with regardto water infiltration. Leaking windows on anew or existing building are major factorsin construction li tigation today. Indus try-

standard testsexist for resistance to waterpenetration bywindows. Fieldtest ing is performed ina c c o r d a n c ewith ASTM

Photo 1 – An interior-mounted pressure chamber on a large, triple- mulled window assembly on a project in Houston, TX.

Photo 2 – A pressure chamber mounted directly tothe precast concrete panel at a window mock-up

for testing on a project in New Orleans, LA.

E1105, “Standard Test Method for FieldDetermination of Water Penetration ofInstalled Exterior Windows, Skylights,Doors, and Curtain Walls by Uniform orCyclic Static Air Pressure Difference,”and/or AAMA 502. However, it should benoted that AAMA 502 refers to ASTM E1105for the actual field procedure and test appa

ratus requirements. The difference is thatAAMA 502 describes the manufacturer’srequirements for field test specimens, sampling, and reports to be used in verifying thewater penetration resistance of windows.

ASTM E1105 is a test standard intended primarily for determining the resistanceto water penetration through windows forcompliance with specified performance criteria. To perform ASTM E1105 water testing, a chamber is typically made andattached to the interior or exterior wall thatborders the frame of the specimen ( Photos 1and 2 ). A mechanical blower is then used toexhaust air from the chamber if installed onthe interior or supplying air to the chamberif installed on the exterior at a rate required

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Photo 3 – Water spray from a spray rack is applied from the exterior at a prescribed pressure and distance from the wall as stipulated in ASTM E1105.

to maintain the specified pressure difference across the specimen. Simultaneously,water is sprayed onto the outdoor face ofthe specimen at a rate required by the teststandard, and the specimen is observed forwater penetration ( Photo 3 ). The water-spray rack should be built to deliver wateruniformly against the exterior surface of thetest specimen at a minimum rate of 3.4

L/m2

•min (5.0 U.S. gal/ft2

•hr). This ratecorresponds to a rainfall of 20.3 cm (8.0in)/hr. The water spray rack should havenozzles spaced on a uniform grid located auniform distance from the test specimenand should be adjustable to provide thespecified quantity of water in such a manner as to wet all of the test specimen uniformly and to wet those areas vulnerable towater penetration ( Photos 4 and 5 ).

ASTM E1105 describes two differenttest procedures. Procedure A is a test underuniform static air-pressure difference. This

test procedure requires applying the specified static air-pressure difference whileapplying the water spray at the specifiedrate for a continuous 15 minutes. Pro cedure B is a test of cyclic, static air-pressure

difference. This test procedure requires applying the specifiedstatic air-pressure difference while applying the water sprayat the specified rate for a five-minute duration cycle (unlessotherwise specified by the project requirements). After thefive-minute cycle, while maintaining the water spray, reducethe air-pressure difference to zero for a period of not less thanone minute. This five-minute to one-minute cycle should berepeated a minimum of three times for a total pressure application of no less than 15 minutes. The number of cycles canbe greater, however, if required by the product specifications.

The window product performance class typically dictateswhich procedure should be utilized on a particular window

Photo 4 – A water spray is constructed to test windows ona slight radius on a high-rise building in Houston, TX. Partof the window assembly extends past the edge of thebalcony, so swing-stage equipment was utilized to support

portions of the water-spray rack during the testing.

Photo 5 – The spray rack is placed to test a mock-up on a project in New Orleans, LA. The spray rack is placed on thetest specimen so that the nozzles spray the water in such a

manner as to wet the entire test specimen uniformly.

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Figure 2 – Figure 1 from AAMA 502-02, Test Method A.

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“If no window manufacturer will guarantee or provide a warranty

that its products will withstand water penetration equal to the

ratings in which they are tested in the lab and certified for their performance rating, how will this affect the windows that we

design, specify, and install in our buildings?specimen.

AAMA 502 refers to ASTM E1105,described above, for the test procedure, butas previously mentioned, AAMA 502 furtherdefines the testing in the field. Althoughmany people are familiar with AAMA 502,they are unfamiliar with the recentchanges. Previously, AAMA 502-02 wastitled “Voluntary Specification for Field

Testing of Windows and Sliding Glass

Doors.” The new AAMA 502-08 is titled“Voluntary Specification for Field Testing ofNewly Installed Fenestra tion Products.” Thebiggest difference between these two is thatthe AAMA 502 can no longer be used forwindows that have been installed for morethan six months. It is only to be used dur

ing construction, prior to an issuance of thebuilding occupancy permit, but no laterthan six months after installation of the fenestration products. One of the main reasonsfor this change is to discover correctionsthat need to be made during the construction process in order to minimize financialimpact on the responsible parties. After theproducts have been installed for sixmonths, the AAMA 502 test standard now

references AAMA 511-08, “VoluntaryGuideline for Forensic Water Penetration

Testing of Fenestration Products.”AAMA 502 also now differs with regard

to its test methods. Previously, AAMA 50202 described two different test methods.

Test Method A was conducted to test thefenestration product within the confines ofthe perimeter of the main frame ( Figure 2 ).

This test method only tests the operable elements (sash, vents, panels) and fixed glazing components under the specified pressure for water penetration. Test Method Bwas conducted to test the fenestration product, inclusive of the joint between the fen

estration product and the rough opening.With this test method, the chamber isinstalled to the wall construction in such amanner as to create the pressure differential across the entire fenestration product(including the subframe/receptor and/orsill pan) and the perimeter seals ( Figure 3 )Now, AAMA 502-08 describes only one tesmethod. The test method described above

as Test Method B is the only test descriptionin the new AAMA 502 standard. As such,Figure 3 from AAMA 502-02 is the only figure in AAMA 502-08 that shows the testchamber. This change suggests that theAAMA 502 standard will now always testhe entire assembly – including the windowitself and the installation of that window –for water penetration.

As mentioned above, ASTM E1105describes two different test procedures.AAMA 502 designates which test procedures should be performed in the field,

based on the performance class of the window. This has changed in the latest versionof AAMA 502 and should be understood toensure the proper test procedures are beingperformed in the field.

AAMA 502-02 previously stipulatedProcedure B (cyclic, static test pressure) forresidential (R), light commercial (LC), andcommercial (C) performance-class fenestrations; Procedure A (uniform static test pressure) for architectural (AW) class products;and both Procedures A and B for heavycommercial (HC) class products. AAMA502-08 now stipulates Procedure B for allperformance classes except for AW win


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Figure 3 – Figure 3 from AAMA 502-02, Test Method B.

dows, which shall be tested usingProcedure A. AAMA 502-08 goes further tostate that Procedure A shall consist of a single 15-minute test as described in ASTME1105, and that Procedure B will consist offour cycles consisting of five minutes withpressure applied and one minute with thepressure released. This is above the minimum described in ASTM E1105 and shouldbe understood when performing field tests.

Perhaps the greatest difference withregard to the changes in AAMA 502, and theone that potentially affects the selection ofwindow products, is the change regardingthe water-penetration resistance pressuresto be tested in the field. Both AAMA 502-02and AAMA 502-08 state that the water penetration resistance testing in the field shallbe conducted at a pressure equal to two-thirds of the tested and rated laboratoryperformance test pressure. For example, anHC 50 window is a heavy commercial window with a performance grade of 50 psf.

The laboratory performance test pressurewith respect to water penetration resistanceis 15% of the performance grade, or 7.5 psf.However, using the AAMA 502 reduction,the appropriate field test pressure for thewindow is 2/3 x 7.5 psf, or 5.0 psf.

Previously, AAMA 502-02 included anote after discussing the two-thirds reduction that stated, “The specifier is permittedto increase the field water penetration resistance test pressure to the value specified forthe project.” This allowed the design professional or specifier to require that the fieldtesting of the installed window was equal tothe lab test or 15% of the design pressure

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calculated by the architect or structuralengineer of record. In this author’s opinion,any window installed in a building thatcould not meet the water penetration resistance equal to 15% of the calculated designpressure would be unacceptable for thatbuilding. Many architects or engineers arein the practice of writing in their specifications that there be no reduction in the fieldtest pressures. Now, AAMA 502-08 includesa note stating:

The field installation conditions alsoinfluence the product performance.Products tested in the laboratory areperfectly plumb, level, and square ina precision opening. Field test specimens, although installed withinacceptable industry tolerances, arerarely perfectly plumb, level, andsquare. Shipping, handling, acts ofsubsequent trades, aging, and otherenvironmental conditions all mayhave an adverse effect upon the performance of the installed specimen.A one-third reduction of the testpressure for field testing is specifiedas a reasonable adjustment for thedifferences between a laboratory testenvironment and a field test environment.

Another section of AAMA 502-08,Specifier Note 4, states:

When selecting static water testpressure to be tested at the job site,in no case shall the specified test

Test your knowledge of building en-velope consulting with the followingquestions developed by Donald E.Bush, Sr., RRC, FRCI, PE, chairman ofRCI’s RRC Examination DevelopmentSubcommittee.

1. How does a curtain wall or

window system design allow forthe thermal movement ofmaterials of different thermalexpansion coefficients?

2. Describe how to wet-glaze failed,shrunken, and dry-glazinggaskets at a window unit.

3. What purpose do end dams servein a glass curtain-wall system ?

4. What are the most commoncauses of adhesive failure at asealant joint?

5. A new low-slope roof system isbeing installed with a one-quarter in/ft roof slope. The roofslopes north to south and southto north to a drain valley thatequally divides the area to bedrained. The drain valley is deadlevel and has two drains, one ateach end. A cricket with a one-half in/ft slope is to be installedbetween the drains. The cricketwill be 60 ft long and 30 ft wide.What will the slope-to-drain be atthe drain lanes of the cricket?

6. How many board feet of insulation are required to build a one-half in/ft tapered cricket that is60 ft long and 30 ft wide for theroof described in question #5?(Assume a minimum insulationthickness of zero.)

Answers on page 12

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Answers to questions from page 11:

1. Properly designed sealant jointsand the right sealant willaccommodate the movement.

2. Cut dry gasket to form a 90degree angle between window

glass and metal. Solvent wipeglass and metal to cleansubstrate. Install silicone sealantwith ± 50% movement rating.Tool fillet bead to ensure acomplete seal.

3. They contain any water withinthe aluminum channels at thehorizontal/vertical intersectionand route the water out throughthe window weep system.

4. Improper surface preparation,substrate contamination, andimproperly tooled sealant.

5. a 2 + b2 = c2

15 2 + 30 2 = 1125 √ 1125 = 33.54 ft = length of

drain lane

¼ x 15 = 3.753.75 1 slope along= =33.5 8.9 drain lanes

6. (Total area of cricket) (Averageinsulation thickness) = Cubic feetof insulation

(Cubic feet) (12) = Board feet ofinsulation

900 x .625 x 12 = 6750 BF

REFERENCES:Questions 1-4 – SWRI WaterproofingManualQuestion 5 – NRCA Energy Manualandbasic geometryQuestion 6 – NRCA Energy Manual

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pressure exceed two-thirds of thetested or rated laboratory performance.

In discussing new AAMA 502 requirements for field testing and performancerequirements and ratings with numerouswindow manufacturers, this author has notfound any window manufacturer who will

state, claim, certify, or warrant that any ofits products will withstand water penetration in the field at the same test pressurethat the product is tested in the lab.

This poses a significant concern withregard to designing, specifying, and testingof windows. Industry standards for windowmanufacturers dictate that:

1. Windows must withstand waterresistance of no less than 15% of thewindow products’ performance ratings,

2. The performance rating is equiva

lent to the design pressure calculated for a building from code requirements, and

3. Building codes establish minimumrequirements for design, construction, and quality of materials, etc.

If no window manufacturer will guarantee or provide a warranty that its productswill withstand water penetration equal tothe ratings in which they are tested in thelab and certified for their performance ratings, how will this affect the windows thatwe design, specify, and install in our buildings? Even if we, as design professionals,specify windows that are equal to the designpressures calculated for a building by thenew AAMA 502-08 test standard, it is safeto assume that water infiltration could

potentially result under “typical” conditionsbased on standard building codes.

CONCLUSION

Uncontrolled water penetration in abuilding exterior – especially windows – is asignificant issue that we face in construction today. The basis of much constructionlitigation deals with damage resulting from

leaking windows. Architects and/or engineers of record for projects responsible fordesign and specification of window productsneed to understand the industry test standards that are utilized by manufacturerswith regard to their ratings and guaranteesfor water penetration resistance. It is theresponsibility of the design professional tospecify systems that, at a minimum, meetthe code requirements for the building. Thatbeing said, is it prudent or necessary tospecify a window product that is rated higher than the calculated building code

requirements to ensure that the guaranteedand warranted water penetration resistanceof the product meets accepted industrystandards and building code calculatedpressures? Interpretation of the code, theindustry standard water penetration tests,associated reductions with regard to fieldwater testing, and ultimately, the specification of the product, are the decisions of thearchitect or engineer of record. However,having a complete understanding of windowratings and test standards will help thedesign professional make the proper decisions when designing, specifying, and stipulating water penetration testing requirements for windows in buildings. Let’s hopethey don’t leak.

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Robért Hinojosa, RRC, RWC, RRO, PE, CDT

Robért Hinojosa, RRC, RWC, RRO, PE, CDT, is the principalengineer and a primary shareholder of Building Engineering-Consultants, Inc. (BE-CI or www.be-ci.com), an engineering

consulting firm that specializes in investigation, repair,design, and restoration of building envelopes based in Destin,FL, with offices also in Gulf Shores, AL, and Houston, TX.BE-CI and Hinojosa perform extensive water testing on existing construction for forensic purposes, as well as performance testing on new construction throughout the U.S. andthe Caribbean. Hinojosa has a bachelor’s degree in civil engineering from Texas A&Mand a master’s in business administration from the University of Houston. He is a registered professional engineer in Texas, Louisiana, Mississippi, Alabama, Florida, andGeorgia; and he is a Construction Document Technologist (CDT) through theConstruction Specifiers Institute. Robért is a member of RCI, CSI, ASCE, and is the current president of the Florida Panhandle Branch Chapter of RCI, Inc.

the effect of changes of aama 502 standard

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