In a heavy rain, an astonishing quantity of water descends on your house. When all goes well, the water flows smoothly off the roof and into the gutters, where it gets funneled into the downspouts and drains away from your house.
When things don't go so well, water backs up in the gutters and overflows before it can drain. That can happen if a gutter or downspout is clogged, or if a gutter doesn't have the required slope down toward the nearest downspout. It can also happen if the downspouts are too few or too far between, and they simply can't drain a roof's worth of water fast enough.
Gutters should slope 1/2 inch for every 10 feet toward a downspout. For gutter runs longer than 40 feet, it's best if the gutter is pitched down from the middle to a downspout at each end. They can also be sloped down from each end toward a single downspout in the middle of the run.
If you see water building up in the corners of the gutter, or overflowing from a straight run, first check for clogs and debris. If the water's still not flowing properly after you've cleaned them, your gutter may be improperly pitched or your downspouts may be inadequate for the flow. If either of those is the case, adding an extra downspout will help keep the water flowing away from your foundation.
Adding a downspout is not difficult, says Chris Freeman, owner of Exterior Specialist in Carpentersville, Illinois, and a gutter installer for more than a decade. "All it takes is a little measuring, a little bit of cutting, and a fitting of pieces together like a small puzzle." On the following pages, Freeman shows how to install a downspout, step by step.
