How air, water and wind tests are carried out on curtain walls, what the classes mean and why mock-ups matter.
Whether a curtain wall works for years without leaking, whistling or being damaged in storms depends on the performance classes set at design stage and on verifying them by testing. In Türkiye, curtain walls are placed on the market with CE marking under the TS EN 13830 product standard, which defines the test methods for its essential characteristics.
Air permeability (EN 12153 / EN 12152)
Positive and negative pressure is applied to the specimen in stages and the air passing through the facade is measured. The result is expressed as classes A1 to A4, or as AE (exceeding) for pressures above 600 Pa. Tall buildings typically target AE.
Watertightness (EN 12155 / EN 12154)
Water is sprayed onto the facade at a constant rate while the pressure is increased in stages; the pressure at which the first leak appears sets the class. Classes R4 to R7 are used, with RE (for example RE1200) above 600 Pa. RE1200 or higher is recommended for coastal and high-rise projects.
Wind load resistance (EN 12179 / EN 13116)
The specimen is loaded up to the design wind pressure while the deflection of mullions and transoms is measured, then checked for permanent damage under a safety load of 1.5 times the design value. The design wind pressure is calculated to TS EN 1991-1-4 according to the building's location and height.
Mock-up testing
A laboratory report covers a standard system specimen of particular dimensions. Project-specific details, different glass sizes, corners and slab-edge details can only be verified with a full-scale mock-up. A mock-up is usually two storeys high and at least two or three panels wide, and goes through air, static water, dynamic water (wind-driven rain simulated with an aero engine), wind and repeat water tests in turn.
On-site water testing
Laboratory tests verify the design; to verify installation quality, water tests are carried out on site. Water is sprayed onto selected joints with a calibrated nozzle and checked from inside. On our projects we carry out at least one site water test per 1,000 m² of facade and add the results to the as-built file.
Advice for clients
Stating performance classes clearly in the specification makes it easier to compare bids from different contractors. On tall buildings and coastal projects, adding a mock-up test to the specification removes major risks for a small percentage of the total budget.
Where do tests fit in the programme?
Mock-up fabrication and a laboratory slot usually take 8–10 weeks, and any detail revisions following the test must also be allowed for. The mock-up should therefore be planned in parallel with shop drawing approval, and series production should not start until the test has been passed.