Over time, seals can

…Therefore, if there is no good ventilation in the house, moisture may accumulate in it, which, condensing, forms glanced areas on the windows.

Over time, seals can be damaged and unusable. To extend the service life of the seals, you need to process them every six months for cleaning rubber parts, thus cleansing of dirt and dust. It is also necessary to take care of drainage — channels intended to remove moisture. To get to them, it is necessary to open a window sash — the drainage excesses are located at the bottom of the window frame. Of them periodically you need to remove the accumulated dirt. Plastic windows also need regular care. So that the hardware serves for a long time — periodically lubricate moving details. Do not use the products of manufacturers unknown to you to lubricate, instead of increasing the service life, they can significantly reduce it.