Weep Holes

Weep holes are small openings — typically slots or round holes 3–6mm wide — located at the bottom of a window frame, usually on the exterior face of the sill. They serve one critical function: drainage. When water enters the window frame cavity (from condensation, wind-driven rain, or through the glazing gaskets), weep holes provide an exit path so the water drains out instead of pooling inside the frame where it can cause damage.

Why Weep Holes Matter

A vinyl or aluminum window frame is essentially a hollow extrusion. During wind-driven rain, water can enter through the gaps between the glass, gasket, and frame. Without weep holes, this water has nowhere to go and accumulates in the sill track. Over time this causes:

• Corrosion of metal hardware inside the frame
• Mold growth in the frame cavity
• Rot in wood components nearby
• Water overflowing into the wall or onto the interior sill

Blocked Weep Holes

Weep holes can become blocked by: paint overspray, debris (insect nests, dirt), or overly aggressive caulking by homeowners who mistake them for gaps to seal. A blocked weep hole is a common cause of water infiltration complaints in otherwise sound windows. Inspect them annually and clear with a thin wire or toothpick if needed.

Common Mistake: Caulking Weep Holes

Never caulk weep holes. They are intentional drainage points, not errors in the installation. A homeowner who caulks weep holes to stop wind noise (the holes can whistle slightly in high winds) may end up with a water-damaged window frame within a few years. If wind noise is a problem, weep hole covers — small plastic baffles — allow drainage while reducing noise.