If you’re planning to invest in new doors and windows, it’s natural for you to want to know you’re getting the best possible product. A number of different tests are carried out in order to ensure product quality and performance.

There is a comprehensive regime of tests which can be used to measure the performance of a window or door.


Class1 (less tight), Class2, Class3, Class4, Class5, Class6, Class7, Class8, Class9 (super tight) under testing method ‘A’ *

As the name indicates, this test is designed to examine a door or window’s resistance to water pressure. To carry out the test, a uniform water spray is applied to the surface area and air pressure increased. This continues until either the necessary standard has been met or until the water has penetrated the surface.

Performance on this test is measured in classes, with Class 1 indicating 15 minutes of pressure with no leaks. Once Class 1 has been met, pressure is increased in increments of 50Pa every five minutes until the test has reached Class 7.

Above Class 7, the pressure is increased in larger increments of 150Pa every five minutes: again, this continues until either the necessary standard is achieved or until the pressure becomes too much.

If a door reaches Class 9, the final levels of performance are graded by an E followed by the maximum pressure endured. So, if a door had endured 900Pa, it would be given the class E900.

*There are two Resistance Classes for testing – A and B. Method A test has products fully exposed, Method B test has products partly exposed.


Class 0 (Lowest), 1, 2, 3, 4 (Highest)

Air Permeability refers to the amount of air that will travel through a window or door system in its closed position.

The classes for EN12207 (EN1026) range from class 0 (the lowest) to class 4 (the highest). Class 4 indicates that the window or door system has been tested under pressures up to 600 Pa and had below the class limit of air permeability through the system along the panel joint and overall system area.


C1 (lightest), C2, C3, C4, C5 (strongest)

This is a test of a door or window’s overall strength – an important attribute during those chillier, windier months! The test is conducted in a similar manner to the water pressure test, where the levels of air pressure are increased slowly to measure the extent to which the windows and doors bend and at which point draughts begin to get through.

Performance tests for Pressure, is grouped into 5 classes: Class 1 is the lowest level of performance. A Class 5 door or window is capable of withstanding 2000Pa of pressure, which is the equivalent to 127mph winds. Anything above 74mph is classed as hurricane force.


RC1 (occational), RC2, RC3, RC4, RC5, RC6 (experienced)

European Standard EN1627 subjects windows and doors to a number of static and dynamic loads, designed to test both the materials and the locks. The test also includes attempts to break in using specified tools. For this standard, windows and doors may be categorised into six classes, RC1 to RC6.

For domestic use, though, the standards are only RC1 to RC3.


Class 1 (25 – 29 decibels), Class 2 (30 – 34 decibels), Class 3 (35 – 39 decibels), Class 4 (40 – 44 decibels), Class 5 (45 – 49 decibels), Class 6 (over 50 decibels)

This indicates the ability of elements to reduce the noice pollution. Effective sound insulation is equally dependent on sealing the windows during the installation process using the
appropriate glazing tape, etc.


The ability of an element to transmit heat from a warm space to a cold space in a building, and vice versa. The lower the U-value, the better insulated the building element.

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