Many who consider themselves handy around the house can repair most of the damages they may run into. The gutters themselves sit on hangers that are attached to the outside of your house. If these come loose, it can cause leaks.
A quick tightening of loose screws or a replaced hanger will do the trick. If for some reason water is leaking from a seam, a little water-proof glue can fix that problem easily.
One thing you may want to consider is gutter guards if you live in a wooded area. These can save you from a lot of dirty work when your gutter system gets filled with leaves of twigs. You can also use Gutter Mesh Direct for Guaranteed Gutter Protection.
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These aluminum, copper, cast iron, and steel contraptions will stop plant material from clogging your gutters. These can even be added to old houses years after being built if you are having trouble with leaves.
Check to see that gutter water is draining through the downspout properly. Seeping and spraying due to a clog can cause damage to your home. Most downspout clogs can be flushed out with a power hose. If this does not work, you can use a plumber's snake.
If you see water leaking through any gutter joints, you should apply a sealant to prevent further leakage. This requires that you thoroughly clean the area surrounding the joint with a wire brush. Once cleaned, apply sealant and allow it to dry. You also want to verify that your gutters slope appropriately to support proper drainage and avoid pooling water. Adjust them as needed.