Installing windows with PU foam

Around 80 % of all windows in Germany are insulated with construction foam. There are four good reasons for this high percentage:

1. It provides the best insulation.

A comparison with other insulation materials shows that PU foam has the best thermal insulation values and therefore saves the most energy.

Chart: Comparison of insulating values

2. It is fast.

Trade professionals can insulate window joints with assembly foam two to three times more quickly than with mineral wool.

3. It is safe.

Window foam easily compensates uneven areas in the joint. As PU foam continues to expand after it has been applied, it also reaches difficult-to-access areas reliably.

4. It is efficient.

Thanks to its high adhesive strength, it forms very good, durable connections between windows/frames and materials such as concrete, masonry, stones, plaster, wood, fibre cement, metal and many plastics.


PU foam saves time and costs, and insulates the best. Our website outlines what properties a good window foam must have and what you should be aware of when purchasing foams.

Please note:

Selection of the right PU foam is an important factor for professional window fitting. Window fitting also includes other important steps that cannot be illustrated here. The RAL Window Fitting Guide itself is 300 pages long. For example, you will find more information here: Verband Fenster und Fassade (Assembly guide)

Installing windows just with PU foam – is that possible?

Time and again, there are reports stating that windows can be installed and insulated only with the help of PU foam. Other contributions, by contrast, explicitly point out that this is not possible. So which is it? The PU Foam Info Centre asked the German expert for professional window installation, Dipl.-Ing. Wolfgang Jehl from ift Rosenheim..


Read more about Dipl.-Ing. Wolfgang Jehl

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