How do you know it’s time to repaint the windows?

Check the windows every year. If you see cracks in the putty and paint at the bottom of the window frames, it’s a sign that it’s time to repaint. This is where the windows are most vulnerable. If the window is otherwise good, it may be enough to paint the bottom piece and about 20 cm up the sides. But remember that even if you’re only going to paint the base, it should be done thoroughly.