A gutter is a channel along a roof edge that collects and diverts rainwater. It is part of the roof drainage system. The gutter catches water as it runs off the roof. The downpipe carries it to the ground. Without a gutter, water would pour off the roof and erode the soil, damage the foundation, and stain the walls. The gutter is a simple but essential component. It protects the building from water.

Gutters come in several types. A sectional gutter is made of short pieces joined with connectors. A seamless gutter is formed on site in long runs, reducing leaks. The material can be aluminum, copper, steel, vinyl, or zinc. Aluminum is the most common. Copper is durable and develops a patina. Vinyl is cheap but brittle. The gutter is sized based on the roof area and the rainfall intensity. Too small, and it overflows. Too large, and it is wasteful. The gutter must slope toward the downpipe. A slope of 1/16 inch per foot is typical.

Gutters need maintenance. Leaves and debris can clog the channel and the downpipe. Water backs up and overflows. The fascia and soffit can rot. Mosquitoes can breed in standing water. Gutter guards, screens, and covers reduce clogging but do not eliminate it. The gutter must be cleaned at least once a year. In cold climates, ice dams can form, forcing water under the shingles. Heat cables and proper insulation help. The gutter is not glamorous. It is the first line of defense against water. It works quietly. It fails loudly.