Gutter leaking at the seams

How gutter joints are sealed

Sectional gutters are joined at seams, corners, end caps and downspout outlets, and each joint is held with rivets or screws and sealed with sealant on the inside. Seamless gutters have no seams along their length, but they still have sealed corners, end caps and outlets. Over the years the sealant dries out, and the metal expanding and shrinking with the weather works the joints loose.

A dripping seam doesn't sound like much, but it drops water right next to the house, onto the fascia board behind the gutter and down along the foundation. Gutters that don't slope toward the downspout leave water sitting at the joints, which makes them fail sooner. New sealant has to go onto clean, dry metal to stick, so a little prep matters more than the sealant itself.

Why gutter seams leak

Let's fix it

1. Find exactly where it dripsWatch the gutter during a rain, or run a garden hose into the gutter at the high end and watch from the ground. Mark each seam, corner or end cap that drips. While water's running, notice whether it pools anywhere instead of flowing to the downspout. Clear out leaves and grit before you go further; there's a separate guide for cleaning gutters.
   Done

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2. Clean and dry the jointAt each leaking joint, scoop out debris and scrub the inside of the seam with a stiff wire brush. Wipe it with a rag and let it dry completely, since sealant won't bond to wet metal. If the sealant label calls for it, wipe the area with rubbing alcohol to remove grime and oils.
   Done

   Something went wrong?

   • The seam won't dry Wait for a dry, warm day; sealant won't bond to damp metal.

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3. Scrape off old sealantUse a putty knife to scrape away cracked, peeling or loose sealant along the seam and around rivet heads. New sealant sticks poorly over old sealant that's already failing. Brush away the scrapings and wipe the joint again.
   Done

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4. Tighten a loose jointIf the two pieces have pulled apart or a rivet is loose, pull them back together. Drill out a bad rivet and replace it with a new pop rivet or a short sheet-metal screw. Match the fastener to the gutter: aluminum rivets on aluminum gutters, steel or stainless on steel, and copper on copper, since mixing metals can cause corrosion. A tight joint gives the sealant a thin gap to fill instead of a wide one.
   Done

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5. Seal the seam from the insideRun a continuous bead of gutter sealant along the seam on the inside of the gutter, covering the joint and the rivet heads. Smooth it with a putty knife or a gloved finger so it feathers out onto the metal on both sides of the joint. Seal corners and end caps all the way around. Let it cure for the time on the label before rain or testing with the hose.
   Done

   Something went wrong?

   • It still drips after sealing The sealant may not have cured before rain, or the joint is still loose; tighten it and reseal.

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6. Patch small holesFor a small hole or rust spot, scrub the area clean, cut a patch of aluminum flashing that extends a couple of inches past the hole on every side, and bed it in a layer of gutter sealant inside the gutter. Press it down flat and seal around its edges. If a section is rusted through in many places, replacing that section is the better fix.
   Done

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Watch it done

How To Reseal Old Leaking Gutter JointsBy Start A Rain Gutter Business on YouTube. Their method may vary a little from ours.

Watch on YouTube

If it's not the seams

If water spills over the front edge instead of dripping at a seam, see the guide for cleaning gutters.

If the gutter is sagging or pulling off the fascia, check our guide for a gutter pulling away from the house.

Leaking gutter seam questions