How Are Curtain Wall Air, Water, and Wind Performance Tested?

A curtain wall is tested twice. Once in a laboratory on a sample nobody will ever live behind, and once on the actual building after it has been erected by real installers in real weather.

Both matter, and they catch different problems.The laboratory mock-up proves the system design. If it fails there, the detailing is wrong and it gets fixed before the facade goes into production. The field test proves the installation. A system that passed every laboratory test will still leak if the gaskets were compressed badly or a corner seal was missed.

Projects that skip the second test discover the difference during the first serious rainstorm, usually after the interior fit-out is complete. This article covers both sequences and what the reports should contain. PRANCE publishes technical documentation covering test evidence for the systems we supply.

The Three Performance Requirements

Air, water, and structural, tested in a defined order because each one can affect the next.

• Air infiltration measures how much air passes through the assembly at a given pressure difference. Excess leakage wastes energy, carries moisture into the construction, and usually indicates seals that will also leak water.
• Water penetration measures whether water reaches the interior under simultaneous spray and pressure. This is the test that generates the most failures.
• Structural performance measures deflection and permanent set under design wind pressures, both positive and negative.

The sequence runs air, then water, then structural, then air and water repeated. Repeating after the structural test matters, because a system that seals well before being flexed may not seal afterward.

Curtain Wall Air Infiltration Test

Tested to ASTM E283 in North American practice and EN 12152 in Europe.

The specimen is sealed into a chamber, a pressure difference is applied, and the airflow required to maintain it is measured. Results are expressed as flow per unit area or per unit length of joint.

• ASTM E283 typical commercial requirement: 0.06 cfm/ft² at 75 Pa (1.57 psf)

• Tighter specifications: 0.03 cfm/ft² or lower

• EN 12152 classification: classes A1 to A4, with AE for higher performance

• Fixed lights are tested against area, operable vents against crack length

Leakage above the specified rate usually points to gasket compression, corner joints, or the junction between the glazing pocket and the drainage cavity.

Curtain Wall Water Penetration Test

The test that finds most problems, and it comes in static and dynamic forms.

Static Water Testing

ASTM E331 in North America, EN 12154 in Europe.

Water is sprayed uniformly across the exterior at a defined rate while a constant positive pressure difference is applied. The standard calls for 5 gallons per square foot per hour, applied for 15 minutes.

Test pressure is typically specified as a proportion of design wind pressure, commonly 20%, with a minimum often set around 300 Pa (6.24 psf). Higher values are specified on exposed sites.

Failure is defined as uncontrolled water appearing on the interior. Water within the drainage cavity that exits through the weeps is not failure, since a pressure-equalized rainscreen is designed to manage water rather than exclude it absolutely.

Dynamic Water Testing

AAMA 501.1 uses a propeller to generate a turbulent air stream against the specimen while water is sprayed.

This better represents wind-driven rain than a static pressure difference, since real storms produce fluctuating pressures rather than steady ones. Dynamic testing frequently finds leaks that static testing misses, particularly at corner joints and vertical-to-horizontal transitions.

Cyclic Water Testing

ASTM E547 applies water with pressure cycling rather than constant pressure. The pumping action of varying pressure can draw water through joints that hold under steady conditions, which is why it is specified on demanding projects.

Curtain Wall Wind Load Test

ASTM E330 in North America, EN 13116 in Europe.

Uniform static air pressure is applied to the specimen, positive and then negative, and deflection is measured at defined points.

Two load levels are applied:

• Design load: deflection must stay within specified limits, commonly L/175 for spans up to 4115 mm, with tighter limits sometimes specified

• Overload, typically 150% of design: the assembly must not suffer permanent damage or glass breakage, and permanent set must stay within tolerance

Design wind pressures come from the governing code. ASCE 7 in the United States, EN 1991-1-4 in Europe, and national codes elsewhere, with values derived from basic wind speed, exposure category, building height, and location on the facade. Corners and parapets see higher pressures than the middle of an elevation, which is why zone-specific pressures matter.

Curtain Wall Mock-Up Testing

The full laboratory sequence on a representative sample, usually two or three bays wide and two storeys tall, including the details that are hardest to get right.

What the Mock-Up Should Include?

A mock-up that omits the difficult conditions proves very little. It should contain:

• A typical vision bay and a spandrel zone

• A vertical and horizontal joint intersection, where most leaks originate

• Any operable vent in the system

• A corner condition if the building has exposed corners

• The slab edge and anchor detail

• Any interface with adjacent construction, such as a roof junction or a louvre

Test Sequence

Preload, then air infiltration, then static water, then dynamic water where specified, then structural at design load, then air and water repeated, then structural overload.

Repeating air and water after the structural test is the part that gets dropped under programme pressure, and it is the part that proves the system still seals after being flexed to design load.

Where a mock-up fails, the system is modified and retested. That is the point of doing it before production rather than after, and factory checks that precede the test rig cover what should already have been verified by then.

Curtain Wall Field Water Test

Testing the real facade after installation, which is a different question from testing the system design.

AAMA 501.2 uses a calibrated spray nozzle directed at joints and seals at close range, with a specified water pressure and nozzle traverse rate. It is a check on workmanship rather than a pressure test, and it is quick enough to run on sample areas during construction.

ASTM E1105 is the more rigorous field test, applying spray with a pressure difference across the installed assembly using a chamber sealed to the interior. It replicates the laboratory water test on the actual building.

Field testing is best specified early and run on the first installed bays, so that problems with technique are found while there are still hundreds of bays left to install correctly. Testing at practical completion finds the same problems when fixing them is far more disruptive.

What happens after the mock-up passes covers the erection sequence that field testing checks.

What a Test Report Should Contain?

Four things worth confirming on any report handed over at submittal.

• The tested specimen matches the system being supplied, including profile depth, glazing, gaskets, and anchor type

• The test standards are named with their year of issue

• The pressures applied are stated, both design and overload, and relate to the project wind loads

• The laboratory is accredited and identified

A report for a similar system at a lower test pressure is not evidence for yours. This is the most common gap in curtain wall submittals, and verifying it takes minutes.

Our published certification and test documentation covers the systems we manufacture, and test reports required in the Philippines sets out how jurisdiction-specific requirements add to the standard package.

Where Systems Usually Fail?

Vertical and horizontal joint intersections. The most common leak point in any curtain wall, where three or four sealing planes meet.

Corner conditions. Higher wind pressures, more complex geometry, more joints.

Operable vents. Any opening unit is a weak point unless the hardware, gaskets, and drainage are detailed properly.

Transitions to other construction. Roof junctions, louvre interfaces, and the perimeter where the curtain wall meets structure.

Drainage cavity blockage. Weeps obstructed by sealant, debris, or insulation, so water that entered the cavity by design has nowhere to go.

Glass type and its failure behavior interacts with the structural test, since the overload stage checks that glazing survives 150% of design pressure.

Frequently Asked Questions

1. What is the difference between mock-up testing and field testing?

Mock-up testing proves the system design in a laboratory before production. Field testing proves the installation on the actual building after erection. A system can pass every laboratory test and still leak on site if gaskets were compressed badly or a corner seal was missed.

2. Is water in the drainage cavity a test failure?

No. A pressure-equalized curtain wall is designed to manage water rather than exclude it absolutely, so water entering the cavity and leaving through the weeps is normal. Failure is defined as uncontrolled water reaching the interior.

3. What pressure is a curtain wall water test run at?

Commonly 20% of design wind pressure, with a minimum often around 300 Pa, though exposed sites and demanding specifications call for higher values. The figure should be stated in the specification and reflected in the test report.

4. Why are air and water tests repeated after the structural test?

Because a system that seals well before being flexed may not seal afterward. The structural test loads the assembly to design pressure, and repeating the air and water tests confirms the seals still perform once the frame has moved.

5. When should field water testing be carried out?

On the first installed bays, early in the erection programme. Finding a workmanship problem after a few bays allows the technique to be corrected across the remaining facade. Testing only at practical completion finds the same problems when remediation is far more disruptive.

Getting the Testing Right

Specify the mock-up to include the hard conditions rather than a clean typical bay. Run the full sequence including the repeat after structural loading. Then field test early, on real installed work, while there is still time to change how the crew is sealing joints.

Laboratory evidence proves the system. Only the field test proves the building.

PRANCE manufactures curtain wall systems with mock-up testing, accredited test reports, and field testing support. Send your performance specification and wind load data and request test documentation.