How to Seal Gutter Seams to Avoid Leaks

A length of rain gutter secured to the eaves of a roof.
What You'll Need
Utility knife
Wire brush
Medium-grit sandpaper
Spray paint
Silicone caulk
Caulking gun

Gutter leaks can not only compromise the integrity of your foundation but can also cause flooding in your yard. Rain, snow, hail, wind, and sunlight can all cause metal and plastic gutters to warp and come apart at the seams. Luckily, taking care of these leaks is not hard to do and can be accomplished with some simple tools and steps.

Identify the Leaking Seam

Gutters are a series of pieces of metal or plastic set inside one another, much like shingled roofs. If there is a strong rain, you can probably spot the seam that needs repair because the water will be flowing out of it and the ground will be sopping wet below. Also, gutters are constructed so that debris will not get caught on a seam. If you see leaves or other materials hanging around any particular joint, then that is a clear indication of a leak.

If there is no visible cue, then you have to do some investigative work. Take a ladder and climb up for a closer inspection of the gutter length. You'll want to focus on each segment that rests on the inside of the other pieces, called the "uphill," instead of the ones on the outside, the "downhill."

Disconnect the Seams

A seam occurs where two pieces of gutter intersect. When you do find a dislodged seam, you need to take the two connected pieces apart at the joint where they are caulked together. In addition to caulk, the gutter pieces are often held together by a series of screws. Use the utility knife to cut through the sealant, and then utilize the screwdriver to remove the screws. The pieces will then be easy to pull apart.


Assess the gutter as a whole around the seam that you just took apart. Use the utility knife to scrape away any caulking material that is left on either side and be sure that no other caulk or debris has settled around the joints.

Rust is another factor in gutter leaks, so if you notice any buildup on your metal pieces, this will be the time to take care of it. Use the wire brush to scrape away loose pieces, and then sand the metal to smooth the lip. Go over the area afterward using rust-resistant outdoor spray paint the same color as the rest of the gutter. Make sure this has time to dry completely before you proceed.

Fix the Seam Seal

Use the caulking gun to apply sealant on the inner lip of the gutter segment known as the downhill. Lower the uphill piece back into place and press them together for several seconds to make sure you evenly distribute the caulk. Replace all pieces that make the seam, and then finish by re-adding the screws.