Plastic windows: which variants are there?

Plastic windows can be designed very differently. This applies to the shape of the frame as well as the design features and the special properties of the window. In this article you will find an overview of all common plastic window variants.

Frame shapes

The frames of plastic windows can be designed differently. The individual frame shapes are coded with specific letters in order to be able to describe the respective frame shape quickly and universally.

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Fixed element (F)

Fixed elements are windows that cannot be opened. You don't have a casement. Fixed elements often come in combination with other frame shapes and complement them.

Fixed element with wing (FF)

Fixed elements can also have wings so that they can be opened. In this way, too, they can complement other parts of the window.

Pivot window (D)

Rotary windows can only be opened by turning, but not tilted

Tilt window (K)

Bottom-hung windows, on the other hand, can only be tilted, but not opened by turning.

Turn-tilt window (DK)

These windows can be opened by turning or tilting the sash.

Skylight (O)

It is located above a window and can have a fixed, rotating or tilting sash

Lower light (U)

A lower light is located below a window and can have the same possible properties as the skylight.

Combination of frame shapes

The coding allows an exact description of the frame shape. For example, F-DK-D means that the window consists of three sashes, the first of which is fixed, the middle can be rotated and tilted and the right can only be rotated.

D-DK-OK would then mean that it is a double-sash window. The left wing can only be rotated, the right one can be rotated and tilted, above the two wings there is a skylight that can be tilted.

Design features of windows

A basic distinction can be made between double and triple glazing. In both versions, a so-called "warm edge" can be built in to increase the insulating effect.

In addition, a design as a special sun protection window is possible, or a design as a laminated glass security window (VSG). Special soundproof windows and, for special areas of application, fire-resistant windows complete the range.

Each of these versions has its special design features and fulfills special services in its respective design.

Classification according to resistance classes

Plastic windows can also be classified according to their respective resistance class. The resistance classes according to DIN EN 1627 are based on the design features and the equipment of the frame. DIN EN 356 defines resistance classes for glazing.

Classification according to U-value

Windows with U-values between 0.9 and 1.1 W / (m²K) are considered "energy saving windows". Windows with values above 1.3 W / (m²K) are not permitted.

Below 0.8 W / (m²K) one usually speaks of passive house windows, although these U-value classes are still often used in low-energy houses.

Windows with U-values below 0.6 W / (m²K) are special windows that are only used under special conditions. They are very expensive and currently the absolute limit of what is technically and physically feasible.