Frame weep holes are small openings (holes) made on the aluminum profile to allow water that enters it to drain. Plastic covers (weep hole caps) are placed on top to cover the holes, but primarily to prevent the possibility of strong winds returning the draining water back through the weep hole. Company manuals specify the exact distances and density at which weep holes should be made.
Weep holes are essential for both the frames and the sashes of all types of windows (sliding, casement).
See other reasons why windows leak water or air.
