As a window installer, your primary responsibilities are the installation and the replacement of windows in structures like houses and other buildings. The windows you install are typically pre-made, so you will not have to deal with sizing or cutting glass. Your job duties involve heavy lifting and climbing to fit windows into the correct locations on construction sites or in existing structures. You also make sure your window installations are level, weather-tight, and meet manufacturer specifications. Window installation jobs may last one day or weeks, depending on the size of the structure and the number of windows being installed or replaced.