Weep holes in vinyl windows work in the same fashion as those in wooden or aluminum frames. The small vents in the vinyl frame prevent water from entering the building by draining through the weep holes. Unlike other types of windows, you won't accidentally clog the weep holes with paint or caulk, but you still must ensure they remain free of debris to drain properly.
On vinyl windows and doors, weep holes consist of vented slots on the bottom of the exterior frame. Vinyl replacement windows often are made on each side from the same piece of vinyl, called the extrusion. It is cut into sections and connected together to create the frame. In a vinyl window, the sill is the exact shape as the jambs. This means window tracks holding the sash when the frame is in the vertical position collect and hold water as they act as the sill in the frame's lower horizontal position. Weep holes permit drainage of any water.
Installation and Replacement
If installing or replacing vinyl windows yourself, check to make sure you are placing the window in the correct position so the weep holes are on the outside and the bottom of the sill. If improperly placed on the interior or at the top of the frame, weep holes cannot function, and there is no protection against excess water entering the house. If you find your windows already are incorrectly installed, you may drill weep holes in the proper place to function until the windows are replaced.
No Wind or Water
Weep holes in vinyl windows are designed to keep both water and wind out. Manufacturers install small flaps covering the weep holes, which open out to let water exit and close so wind can't come through the window. In other designs, the outside weep holes for water drainage do not align with inside weep holes, blocking wind from entering.
Periodically check weep holes to make sure the openings are not clogged. Do this whenever you are cleaning the windows, or before the wettest part of the year in your region's climate. If weep holes are clogged, use a screwdriver or soft brush to open them. Remove any debris from the window, such as leaves, dead bugs, dirt and grime to prevent clogging.