Leaks around replaced vinyl windows are more often caused by installer error than by the window itself. Gene Summy, a California contractor that specializes in fixing moisture intrusion problems, describes the efficient practices his crews use for a leak-free installation.

Summy insists it's rarely the window unit itself that's responsible for the leaks. He has tested a wide variety of replacement windows using a calibrated spray rack—which simulates heavy rain in a sustained wind of up to 49 mph—and found that most units exceed their AAMA performance standards for resistance to water penetration, air leakage, and wind pressure. Read more.