Gutters need to be routinely cleaned and maintained to keep them in good condition. However, routine maintenance does not completely protect gutters from damage that may cause them to leak. Leaking gutters need to be promptly dealt with to avoid major water damage problems to your home. Repairing a leaky corner gutter is a simple process that doesn't require a lot of time.
Remove leaves and other debris from the leaking area of the gutter. Wear gloves to protect your hands.
Spray the gutter with a garden hose if the source of the leak is not obvious. A large or small hole is an obvious problem, but leaking joint connections or small cracks may not be obvious. The joint connection between the downspout and the gutter is many times the most likely source of a corner leak.
Scrub the damaged area with a wire brush or abrasive pad. Use an all-purpose cleaner to remove grime and dirt. Rinse with clean water and dry with a towel.
Repair leaking joints with silicone caulk. If water is leaking where the gutter and downspout jointly connect, repair the joint connection. Remove the old silicone caulk from the joint connection. Cut the caulk with a utility knife. Pull it off the gutter with your fingers or a pair of needle-nose pliers. Press the joint connection together to make as tight a fit as you can. Apply a new bead of silicone caulk around the edges of the joints.
Fill small hairline fractures or cracks in the gutters with silicone caulk. Use roofing cement for larger cracks and small holes.
Make a metal patch from a piece of flashing or sheet metal large enough to repair larger cracks or holes. Cut the flashing slightly larger than the hole that is being repaired. Use wire snips to cut the patch.
Apply roofing cement to the damaged area with a putty knife. Apply more roofing cement to the metal patch. Plug the hole with the patch. Smooth out the roofing cement around the edges of the patch. Allow the roofing cement to dry.
Wait for a warm and sunny day to repair the gutter. Silicone caulk and roofing cement adhere better to warm, dry metal.