How to Repair a Leaking Gutter Joint

Most gutter joint leaks can be fixed by cleaning the joint thoroughly, applying gutter sealant or replacing the gasket, and ensuring proper alignment of the gutter sections.

1. Clear Away Debris and Old Sealant. Remove all debris, leaves, and dirt from around the leaking joint using a wire brush or putty knife. Rinse the area with water and let it dry completely. Old sealant or rust must be scraped away to ensure the new repair material adheres properly.
2. Know Your Joint Type First. Determine whether you have a slip joint with rubber gaskets, a mitered corner joint, or a soldered connection. Slip joints are most common and have visible rubber seals, while mitered joints connect at corners. This identification determines your repair approach.
3. Seal Small Gaps Instantly. For small leaks in slip joints or minor gaps, apply a generous bead of gutter sealant along both sides of the joint. Press the sealant into the gap with your finger, ensuring complete coverage. Allow the sealant to cure according to manufacturer instructions before testing.
4. Swap the Gasket Out. If the rubber gasket is cracked or deteriorated, carefully separate the gutter sections by loosening the screws or clips. Remove the old gasket, clean the groove thoroughly, and install a new gasket. Reassemble the joint, ensuring the gasket seats properly in its groove.
5. Patch Major Damage with Flashing. For significant gaps or damaged joint areas, cut a piece of metal flashing slightly larger than the damaged area. Clean both surfaces, apply roofing cement to the patch, and press it firmly over the leak. Smooth the edges and apply additional sealant around the perimeter.
6. Verify Water Flows Freely. Pour water into the gutter upstream of the repair to test for leaks. Check that the gutter maintains proper slope toward the downspout. If water pools at the joint, adjust the gutter hangers to restore proper drainage angle.