Downspout (Downpipe)

A downspout is the vertical pipe that drains a gutter. Water collected along the eaves enters the downspout through an outlet in the gutter bottom and travels to ground level, where it is discharged onto a splash block, into an extension that carries it away from the foundation, into an underground drain, or into a rain barrel or tank. The same component is called a downpipe in Britain, Australia and New Zealand, and a leader or conductor in parts of the United States.

Components

• Outlet (drop): the fitting connecting gutter to pipe.
• Elbows and offsets (swan necks in the UK): bends that bring the pipe from the gutter, which is set out from the wall, back to the wall face.
• Straps or clips: fix the pipe to the wall.
• Shoe: the angled fitting at the bottom that directs water outward.
• Rainwater head (hopper head): an open box at the top of the pipe collecting from one or more gutters or roof outlets, often decorative on historic buildings.

Profiles and materials

Rectangular (corrugated or plain) and round pipes are both common. Materials generally match the gutter: aluminium, galvanised or coated steel, copper, zinc, cast iron, uPVC. Heritage buildings in Britain often have cast-iron downpipes and decorative hoppers.

Sizing and placement

The number and size of downspouts depends on roof area, gutter capacity and design rainfall intensity. As a residential rule of thumb, a 100 mm (4 in) gutter with one 68 mm downpipe has been suggested for about 56 m² (600 sq ft) of roof. Placing outlets near the ends of long runs and at corners reduces overflow. Discharge should be directed well away from foundations, and local regulations may control connection to storm sewers.

Alternatives

Rain chains are a decorative alternative to downspouts, guiding water down a chain or series of cups.