Windows keep the heat inside and keep the cold out. With the right care, they stay tight longer. You should note that.
When a cold wind is blowing outside, it should be pleasantly warm inside. If instead the cool outside air makes itself felt through the window cracks, it is not only unpleasant. This also costs valuable heating energy.
You don't feel a cold draft? Testing whether your own windows are tight is still worthwhile: according to a study by the Window Façade Association (VFF), 235 million of a total of around 634 million window units (one window each with an area of 1.69 square meters) in German residential buildings are considered outdated.
They can lose energy through poor glazing and lack of insulation. Even modern windows can leak due to poor maintenance.
The density test:
You can find out for yourself whether this is the case: "You should put a sheet of paper loosely on the window frame and then close the window," says VFF Managing Director Frank Lange. "If the paper can no longer be pulled out, the window closes well. If you can still remove the paper, on the other hand, there are problems with the tightness."
A lit candle can also help. Guided slowly along the window frame, it flickers where there is a leak, says master carpenter Thomas Gerke from the DIY Academy in Cologne. For a more precise diagnosis, however, he recommends a heat scanner, which is available at hardware stores for little money. "You can use it to identify gaps in the cold not only at the window, but also in other areas of a building."
The problem: Broken seal
The problem is often the seal on the frame, which has been crushed, stuck together or has become porous. "It can also be replaced relatively easily by laypeople," says DIY expert Thomas Gerke. Appropriate meter goods are available in specialist shops.
The old seal must first be completely removed and the area then carefully cleaned. It's best to start in a corner and work your way around. The new seal is carefully but thoroughly pressed into the corresponding groove of the window. This works best if you start in the top middle of the frame.
The problem: warped window frames
Defective seals often indicate a larger problem: over the years, the window frame has warped and presses on the entire construction with its weight.
This can be the result of lack of maintenance and persistent operating errors. Frank Lange from the Window Façade Association advises: "You should make sure that the windows are always closed correctly. Sometimes you see windows where the handles are not turned the full 90 degrees to lock them." Then the full closing pressure is not generated and the mechanical parts of the fittings get caught in each other. If this becomes a habit, the window can warp.
In the case of smaller displacements, amateurs can readjust them themselves, preferably in pairs. "There are adjustment options on the locks, mostly with slotted or Allen screws," says master carpenter Gerke. "At these points you can control the pressure of the window on the frame." One helper should support the window and the other should adjust the screws.
Prevention: window care
Windows show very clearly when they are neglected. "Creaking and crunching noises when opening and closing are a warning signal," says Frank Lange. "This also applies if the windows can only be locked with some effort." The easier it is to open and close windows, the less wear and tear there is.
A little care protects against this. "Every two years at the latest, the inside of the frame should be cleaned and the moving parts there greased," says Lange. Thomas Gerke recommends sewing machine oil to keep the mechanical parts in the window fold in good condition.
The seals also last longer if they are creamed regularly. Gerke advises care products that are intended for car doors. Alternatively, a special window care milk prevents the seals from hardening and losing their effectiveness.
