When you have water leaking in the top of your first floor windows, and you have second floor windows above with a vinyl siding exterior, there is a pretty good chance, your window and siding contractors made some serious errors in the installation of the exterior cladding on your home. We recently received a call from a concerned customer regarding water leaks in their first-floor windows, particularly at the top side. If you are experiencing similar leaks with windows both above and below, there are several important factors to consider through diagnosing this common home problem.