The purpose of a window's weep hole is to drain water away from the window, keeping the water out of the building and protecting the window sill. Found at the bottom of storm window frames, these little holes must be kept clear to function properly. If the weep holes clog for a long period of time, you may end up repairing or replacing a rotten window sill.
Wooden and Vinyl Windows
Wooden and vinyl windows both need weep holes. While a weep hole in a wooden window drains the water and keeps the sill from rotting, weep holes also perform an important function in a vinyl replacement window. The four sides of these windows are made from an extrusion, otherwise known as the lineal piece of vinyl sectioned out and welded, forming the window frame. Weep holes are necessary because the vinyl sill is the same shape as the window jambs, so that the tracks holding the window sash collect and contain water when they function as the sill in the lower horizontal frame position. Without weep holes, this water could not drain.
Windows and Doors with Weep Holes
Double-hung windows usually include weep holes, and so do sliding windows. On sliding windows, the weep holes are under the screen, and operating and sliding sash. Exterior doors may also include weep holes, serving the same purposes as window weep holes -- keeping water out. If doing any remodeling or repair work on windows or doors, do not paint or place caulk over these holes. Weep holes should always be open or they will not perform their basic function.
Checking the weep holes should become part of your annual home maintenance routine. Do it whenever you clean the windows. Make sure the weep holes are open before the wettest season of weather in your area. If weep holes clog, simply push through the debris with a screwdriver, brush or similar object. Keep the window sill free from falling leaves, dust, dirt and grime that could clog these holes.
Creating New Weep Holes
If you discover that your storm windows lack weep holes, put them in by using your drill, with a 1/8 drill bit. Each window frame should have two holes. Also make sure the windows are installed with the weep holes at the bottom, not the top.