Water penetration - "The rain is coming in"
If, for example after heavy rain, you find that water has penetrated the window, it will almost never be the rain water that has come in. The window is protected against rain through the exterior aluminium cladding. The water that has penetrated will usually be condensation. Condensation forms in various ways
Cooling of exterior cladding
When it rains, the exterior cladding is cooled by the relatively cold rain. This results in the area under the cladding also being cooled. Therefore, the gaskets protecting the window from incoming air (draught) will also become relatively cold. If the interior level of humidity is also high the warm humid air will condense on the gaskets. When enough condensation has built up on the gaskets, it will collect in drops and begin running down. Condensation can form in much larger quantities than you imagine.
Read more about Condensation
Changing of gaskets
If your gaskets are old (more than 10 years old), they will probably be stiff and dry. This means they will not be working properly. Warm and humid air will now be able to flow over the gaskets and condense on the exterior cladding and run down at the back of the cladding. At some point the condensation water will drip onto the area between the frame and the sash, and if the gasket is not working properly the water will find a weak spot to penetrate.
You should replace the gaskets so the window closes completely between the frame and the sash. The gasket at the back of the ventilation flap should also seal completely at the ventilation gap.
As it is essential that the correct gasket is used in the correct place, you should let the VELUX Service Department do handle it.
The replacement of gaskets is carried out at a fixed price regardless of where you live in the country. In connection with the service visit we will also provide you with a free check of all your VELUX roof windows.
Let VELUX help you replace the gaskets
Fixing of squre installation
As can be seen from section 2, it is essential the gasket works properly between the frame and sash. If your gaskets are okay and you still experience problems with water coming in - especially when it is cold outside - this may be because the frame and sash are not placed correctly in relation to each other. A square installation may result in the sash not being absolutely parallel to the frame.
You may either contact your roofer to take care of the problem or contact the VELUX Service Department.
Cleaning the flashing
If water penetration cannot be traced to the area between the sash and the frame, but is visible on the lining and/or the inner wall around the window, it may be due to the flashing being filled with leaf fall or moss, preventing the water from freely running away from the window. Instead the water is pressed over the edge of the flashing and onto the roof or into the area between the flashing and the frame. Therefore, it is very important to clean the flashing at least once a year for leaves etc., so that the rain water can run freely away.
Read more about Cleaning the flashing