Why is my gutter leaking at the seam?

The sealant in the joint has dried and cracked, or the rivets holding the joint have loosened as the metal moved with temperature.

What is the best gutter sealant?

A sealant made for gutters, usually butyl rubber or a flexible polymer, that bonds to metal and stays flexible. Avoid general-purpose silicone.

Can I use Flex Seal on gutters?

Spray rubber can stop small leaks for a while, but it is not a lasting fix for open seams. Proper cleaning and gutter sealant hold better.

Why does my gutter drip at the joint only in heavy rain?

The joint may be slightly open, or the gutter may be overfilling there because of a clog or a low spot.

How do I fix a rain gutter leak at the seam?

Clean and dry the seam, remove old sealant, tighten or replace the rivets, then press new gutter sealant into the joint from the inside.

Guides

Leaking Gutters: Finding and Fixing Seam and Hole Leaks

A dripping gutter joint is easy to ignore until the paint below peels or the fascia goes soft. Most gutter leaks are simple to find and fix, as long as you fix the cause and not only the drip.

Updated 2026-10-26 · Gutter Fixing Editorial Team

Gutters leak in a few predictable places: the seams between sectional pieces, the miters at inside and outside corners, end caps, downspout outlets, and holes worn or punched through the trough. Some apparent leaks are not leaks at all: water running behind the gutter because of a missing drip edge, or spilling over the front because the gutter is clogged or sloped the wrong way. Working out which you have is the first step.

Finding the leak

On a dry day, run a garden hose into the gutter at the high end and watch from below or from a ladder.
Look for drips at joints, corners, end caps and around outlets.
Check the fascia behind the gutter: a wet board with no visible drip from the front points to water getting behind.
Look inside the trough for rust spots, cracks and pinholes, especially on older steel gutters.
Note where water stands after the hose stops; pooling means the slope is off.

Why seams and joints leak

Sectional gutters are joined with connectors or overlapping pieces sealed with gutter sealant. Over the years the sealant dries, shrinks and peels as the metal moves with temperature. Rivets loosen, and the joint opens just enough to drip. Corners are worse because they are where two runs meet and where debris collects. On seamless gutters, the corners and end caps are the main joints, so that is where seamless gutter leaks usually start.

Sealing gutters at a leaking joint

Clean the gutter and let the joint dry completely.
Scrape out old sealant and brush the area with a wire brush; wipe with a solvent such as mineral spirits.
If rivets are loose, drill them out and fit new ones, or add a sheet-metal screw.
Apply a gutter-specific sealant along the inside of the seam, pressing it into the joint and feathering the edges.
Let it cure as the label says before running water through.

Use sealant made for gutters, usually a butyl or polymer formula that stays flexible and bonds to metal. Ordinary bathroom silicone does not hold up well. Spray rubber coatings and liquid rubber can seal pinholes and short-term leaks, but they are not a lasting fix for open seams and can make later repairs harder.

How to fix a hole in a gutter

Small holes and rust pinholes can be patched. Clean and dry the area, sand away loose rust, and cover the hole with a piece of matching metal flashing or a gutter patch set in sealant, then seal the edges. Roofing tape made for metal can work on small holes. Larger holes or a trough with rust spots all along its length are a sign the gutter has reached the end of its life. On vinyl gutters, cracked sections are usually replaced rather than patched.

Leaks at outlets and end caps

Downspout outlets leak where the drop is riveted and sealed into the trough. Remove debris, reseal around the outlet flange from inside, and make sure the downspout above the first elbow is not loose. End caps leak when their sealant fails or they were crimped poorly; they can be removed, cleaned, refitted and sealed, or replaced cheaply.

Gutter leaking into the house

If water from a gutter is getting inside, it is usually going behind the gutter rather than through it. Common causes are a missing or short drip edge, gutters hung too low so water runs down the fascia, ice dams pushing meltwater under shingles, or a built-in box gutter whose lining has failed. Each needs a different fix, and the sooner it is found, the less wood has to be replaced. The drip edge guide and the box gutters page cover two of those causes.

Leaks that are really slope or overflow problems

Water pouring over the front of a gutter is not a leak; it means the gutter is blocked, undersized or sloped away from its outlet. Water dripping off the bottom edge along the whole run often means the gutter has been hung too low or the fascia has moved. Sealing joints will not fix either. The blog post on why gutters overflow when they are clean explains these cases.

When to repair and when to replace

Repair: one or two leaking joints, a small hole, an end cap or outlet.
Repair: a sectional system in good shape that needs resealing every few years.
Replace: leaks at many joints along every run, rust through the trough, or repeated failures at the same spots.
Replace: gutters that also sag, overflow or are badly undersized.

Contractors in our network can find the source, reseal joints and patch holes, or quote a seamless replacement if the system is worn out. The gutter repair service page explains that work.

Leaks on different gutter materials

Aluminum seams are sealed and riveted, so most aluminum leaks are fixed with fresh sealant and new rivets. Steel gutters leak mainly from rust, which starts inside the trough where wet leaves sit; once rust has gone through, patches buy only a little time. Copper joints are soldered, and a cracked solder seam needs re-soldering by someone with the right torch and flux, not caulk. Vinyl joints rely on rubber gaskets that can be replaced when they harden.

Preventing future leaks

Clean gutters often enough that debris never sits wet against seams.
Check and reseal corners every few years before they drip.
Keep hangers tight so runs do not flex and crack joints.
Choose seamless gutters at replacement to cut the number of joints.
Fix sagging sections quickly, since standing water finds every weak seam.

Temporary fixes during a storm

If a gutter starts pouring through a split seam in the middle of a storm, there is little to do safely until the rain stops. Put a bucket or tarp under the drip to protect beds and the foundation, move anything valuable away from the wall, and wait. Never climb a wet ladder. Once it is dry, the steps above will fix the joint properly.

Choosing a gutter sealer

The best gutter sealer is a product made for gutters, not general caulk. Gutter seam sealer and rain gutter leak sealer are flexible, stick to aluminum and steel, and stay soft through heat and cold. The best sealer for gutter seams is usually a solvent-based or polymer gutter sealant applied to a clean, dry joint. Rain gutter seam sealer in a tube suits small gaps, while liquid or roll-on coatings cover rusted or pitted sections.

Fixing a leaky gutter joint or corner

Fixing a leaky gutter joint means taking the old sealant out, cleaning the metal, and resealing from inside the gutter. Fixing leaky gutter corners is the same job, with care to cover the miter seams. A gutter leaking at a join between sections may also need a new rivet or two. The best way to fix leaky gutters for good is to replace joints with seamless runs where many joints fail.

Plastic gutter joints

Plastic gutters use rubber seals in clip-together joints. When a plastic gutter is leaking at a joint, the seal has usually shrunk, cracked or slipped. To repair a leaking plastic gutter joint, unclip it, clean it, and fit a new seal or a new union piece. Repairing plastic gutter joints with sealant alone rarely lasts, because the plastic moves with temperature.

Downspout and pipe leaks

A gutter pipe leaking at its joints, or a gutter drain pipe leaking at the elbows, usually has a crimped end facing the wrong way or a loose fastener. Each section should slide inside the one below. Drilling a hole in a gutter to drain standing water is a poor fix; a gutter drain hole without a proper outlet leaks and rusts. It is better to fix the slope or add an outlet.

Can clogged gutters cause roof, ceiling or window leaks?

Yes. Backed up gutters can cause roof leaks when water pools at the edge and is pushed under the shingles, especially with ice. Full gutters can cause a roof leak at the eave, and over time gutters can cause a ceiling leak along an outside wall. Clogged gutters can also cause window leaks when overflow runs down the wall and gets behind window trim.

Quick fixes, concrete and box gutters

A quick fix for a leaking gutter, such as gutter tape or a dab of sealant, will hold until a proper repair. Concrete gutters, found on some older homes and buildings, leak through cracks and need a membrane liner. A conservatory box gutter leaking usually has a failed seal or blocked outlet.