Water tightness testing and ratings in glazing systems

How is water tightness tested?

Water tightness testing is an important process to evaluate the ability of glazing systems to prevent water ingress from entering a space resulting in rot or structural damage. The physical assessment covers all glazing systems from windows and glass doors to water tightness testing on roof glazing systems.

Water tightness to glazing systems within the UK are tested under EN 12208 with the classifications ranging from class 0 to class 9 with the highest (9) able to withstand 600Pa of water spraying pressure for 55 minutes.

Water tightness classifications according to EN 12208

Class	Test Pressure	Spraying Time
	Pa	Minutes
1	0	15
2	50	20
3	100	25
4	150	30
5	200	35
6	250	40
7	300	45
8	450	50
9	600	55

The glass windows and doors are subjected to these powerful jets of water for prolonged periods of time increasing the flow rate in increments of 5 minutes of hose spraying.

The hose spraying testing procedure starts at the bottom of the area typically at the lowest point of the building envelope near the base working across the horizontal structural transom elements to evaluate their ability to prevent water ingress.

The testing process continues by directing water spray up the intersecting mullions of the to assess the weather tightness for the windows and doors.

The testing procedure continues in a systematic manner, moving from the bottom to the top of the area being tested. This ensures that the entire building envelope is thoroughly evaluated for water tightness in one continuous session.

An additional 30 minutes observation time is added. This additional period is referred to as ‘drain down time’.

The drain down time is a critical part of the testing process because it allows for a more comprehensive evaluation of the specimen's ability to prevent water intrusion. It ensures that the specimen can maintain its weather tightness over an extended period, which is important for assessing its long-term performance in real-world conditions.

By including the drain down time in the testing procedure, it provides a thorough assessment of the building envelope's ability to resist water penetration under various weather conditions. This contributes to the overall quality and durability of the structure.

If no water has ingress is found after the 30 minutes drain down time, the test specimen will have passed the weather tightness test.

If you're specifying glazing systems in locations with extreme weather conditions with high wind loads and driving rain, it is pertinent to recommend sliding glass doors over hinged or bifolding doors since the recessed tracking system on ultra slim sliding glass doors prevent water ingress inside the space through its design, whereas bifolding doors typically sit on top of the tracking surface. In addition, we would also recommend using the new rubber gasket seals in our NextGeneration sliding glass doors as they provide more resistance over outdated brush seals.

Learn more about the advanced innovative features in our new Keller NextGeneration minimal sliding glass doors.

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