Weep Holes on Window Frames and Why They Clog

On a slider or single hung window installed in Austin, TX, every small slot at the bottom of the frame matters, and the running record window installation austin tx love my cc holds shows that a blocked weep hole is among the easiest leaks to prevent and among the most common to find. These slots are not decoration, and they are not a defect.

What a weep hole drains

Water gets into a window frame by design. Rain runs along the sash, finds the track, and has to go somewhere. A weep hole is a small opening in the bottom of the frame, usually on the outside face, that lets that water leave. A vinyl window has them cut into the sill, an aluminum window usually has a slot with a small flap, and a fiberglass window follows whichever pattern the maker chose.

Where to look for them

Look at the exterior edge of the bottom rail or the face of the sill nosing. Most units have two or three, spaced along the width, and a wide picture window or slider may have more. On a bay window each section has its own set. A sliding unit with no visible weeps either has them hidden under a cap or has had them sealed shut, which is a problem worth chasing.

What blocks them

Exterior paint is the most common culprit, especially after a repaint where the painter brushed straight across the slot. Caulk is second, applied by someone trying to seal the frame from the outside. Dust, pollen and insect nests close the rest. Austin is full of cedar and oak pollen in spring, and mud dauber wasps use small openings for their nests without asking.

Clearing them gently

Use a thin plastic or wooden pick, a pipe cleaner or a small soft brush, and push only far enough to open the slot. A metal nail can puncture a drain channel or tear a flap. Pour a little water into the track afterward and watch it leave from the outside. Water that still stands in the track after a minute means the passage is blocked further in.

When water stands in the track

Water that pools in the track during a storm and runs onto the sill inside suggests the weeps are closed or the unit was set out of level. A window that is out of plumb sends water to the low corner, and no weep hole at the other end helps. Stains under the stool, swollen wood and peeling paint at the interior sill follow quickly.

A clearing before spring storms takes a few minutes. Treat the weeps like a gutter: unseen most of the year, and the first thing to fail when it matters.