Finding it
The drip is rarely where the leak is. Water runs along the underside of the trough and drops at the low point, which can be feet from the actual joint.
Look for the stain instead. A vertical rust-colored or dark streak on siding or brick below a corner is the giveaway, and it shows up long before anyone notices dripping.
Why the caulk failed
Three usual reasons. It was applied over dirt or oxidation and never bonded. It was the wrong product — general-purpose silicone rather than a gutter sealant rated for metal and movement. Or it was applied in cold weather onto a damp surface.
A joint sealed properly on a dry, clean, warm day lasts years. One sealed over sludge in November lasts until spring.
How we reseal
Scrape and wire-brush the joint back to clean metal on both sides. Solvent-wipe it. Let it dry.
Then a gutter-grade tripolymer or butyl sealant, tooled into the joint rather than smeared over it, with enough thickness to move without tearing.
On a joint that's been resealed several times already, we cut the miter out and refit it rather than adding another layer over old failed sealant.
When it's a symptom
Repeated corner leaks on the same joint often mean the run is moving — expansion with nothing to accommodate it, or a hanger issue letting the gutter shift.
Fixing the sealant on a moving joint just resets the clock. We look at why it's moving.
Questions people ask
Why does my gutter corner keep leaking?
Usually the sealant is failing because the joint moves, or because it was applied over an unclean surface. Repeated failures point to movement.
Can I just caulk it myself?
You can, and it may hold a season. Bare-metal prep is the difference between a season and years, and it's the step that gets skipped.
What sealant works on aluminum gutters?
A gutter-specific tripolymer or butyl product. General-purpose silicone doesn't stay bonded to aluminum through freeze-thaw.
Is a leaking seam worth fixing?
Yes, and early. The water goes into the fascia behind it, and a $200 reseal beats a carpentry bill.
Free estimate
We measure, we look at the fascia, and you get a number in writing.
Talk to a real St. Louis gutter company
Third generation, family-run since 1947. Somebody picks up, day or night.