Step 5 · Apply Window Film

Clean the interior window frame thoroughly. Cut a piece of window insulation film large enough to cover the entire window opening, plus a few extra inches on each side. Use double-sided tape to attach the film to the interior frame, ensuring it is taut. Use a hairdryer on a low setting to gently heat and shrink the film, creating a smooth, wrinkle-free surface. Be careful not to overheat the film.