Leaking windows can quickly drive up energy costs. Here you can find out how easy it is to get the problem under control.

Older houses in particular have leaky windows that can cause heat loss and thus higher heating costs. Subsequent sealing is therefore recommended – also to avoid mold and plaster cracks.

Note for tenants: More complex work that cannot be completely removed should always be discussed with the landlord beforehand.

Various methods can be used to check whether windows are leaking.

A simple possibility is the so-called paper trick. To do this, clamp a sheet of paper between the window frame and sash. If you can easily pull the sheet out when the window is closed, your windows are not sealed properly. Countermeasures are then recommended.

Alternatively, you can hold the flame of a lighter or candle close to your closed window. If the flame begins to dance in the draft, your window is leaking.

Self-adhesive sealing tapes offer a quick and inexpensive way of sealing windows. These tapes have adhesive on one side. Before attaching it to the window, you only have to remove the paper strip over the adhesive. It is also advisable to use a carpet knife or scissors to help. Tip: Before sticking it on, it makes sense to thoroughly clean the area provided for this purpose.

The more expensive alternative to the sealing tapes are the commercially available universal seals. In addition to the higher price, however, these seals also have the disadvantage that they usually do not sit well on the window edges. Before making a purchase, you should therefore first find out about the correct size of the window seal. With this type of seal, a distinction is made between P, E and D profiles. If you are not sure which profile is the right one, take an old seal with you to the hardware store and have them determine it on site. Alternatively, if you don’t want to drive to the hardware store, you can measure the size yourself using graph paper.

When purchasing universal seals, also note the length: Sealing tape rolls are available in 5, 6, 8 or 10 meters.

In the following tables you can see various window seals with different profiles that have been rated as good.

If the cold streams into the apartment between the window and the walls, the use of acrylic is recommended. But beware: Before you buy, you should be aware of where you want to use the acrylic. Depending on the area of ​​application, you can choose between indoor and outdoor acrylic. Outdoor acrylic has the important property of being temperature resistant. This is of great importance for external seals. Depending on the color of the frame, you can also choose between transparent and colored acrylic.

Once you have made your choice of acrylic, it makes sense here, as with the sealing tapes, to clean the surface before processing. Before applying, also remove paint and adhesive residues, for example with a spatula. If everything is clean and dry, nothing stands in the way of using the acrylic sealant.

In the following table we have listed various acrylic products for you.

For this comparison, a specialist editor from our partner CHIP.de examined test reports from other publications as well as the most popular offers (“best sellers”) and customer opinions from online retailers. Based on this, the product selection was made. For the selection of the top devices, models with more than four stars and a reasonably high number of ratings come into question. A selection of customer reviews was read and devices were selected that, based on the professional assessment, meet the needs of the users. The products have not been tested in the CHIP test center.

All products that the CHIP test center had in the laboratory can be found in this overview of the best lists. Products that have also been tested by our other cooperation partners can be found in the test