Overflowing Rain Gutters
Gutters that overflow can present serious problems to your home’s walls and foundation. If your gutters overflow during a heavy rain, either the gutters and/or downspouts are clogged, the gutters are sagging and thereby preventing water from reaching the downspouts, or the gutters and downspouts are not large enough to handle the volume of rain runoff.
In most cases, gutters overflow because leaves and debris are clogging them, essentially creating dams that prevent water from flowing to the outlets above the downspouts. In fact, these clogs often occur right at the outlets. When this is the case, it’s time to clean out the gutters. (For more about this, see Rain Gutter Cleaning & Maintenance.)
Gutters that sag are a different issue—and the more they fill up with water, the more likely they are to sag because they become so heavy when full. If the gutters overflow but are not sagging or clogged, you will probably need to install new, larger downspouts and gutters.
Sagging Rain Gutters
When full of water, rain gutters can become extremely heavy. As a result, the types made of flexible materials such as aluminum, vinyl, and galvanized steel can begin to bend and sag and their hangers to loosen. As this happens, they cease to do a good job of draining rainwater efficiently, allowing water to pool along their lengths. This, of course, just exacerbates the problem, making them heavier and causing them to To determine if your rain gutters sag, check for signs of standing water or water marks along the inner sides of the gutters. With a level, check the slope—gutters should drop about 1/4 inch for every 10 feet of run toward the downspouts.
To fix them, you may need to replace the hangers or, at the very least, re-seat them. If the gutters are held by spike-and-ferrule hangers, use a hammer to drive the long spike, making sure it goes into solid wood. If it does not grab securely, you may need to replace it with an even longer galvanized nail or, better yet, a long screw.