What each gutter and downpipe fitting does, the materials used, and how debris and backflow risks are controlled.
At the gutter
- Running outlet: the fitting with an opening in the base of the gutter, connecting it to the downpipe below
- Stop end: closes off the open end of a gutter run so water is directed along to the outlet instead of running out of the end
- Union bracket: joins two straight gutter lengths and seals the joint, leaving the marked gap for the plastic to expand and contract
- Angle fitting: turns the gutter around a corner while keeping the run continuous, unlike a straight union
- Gutter bracket: fixes the gutter to the fascia at the correct height and fall
- Deep-flow profile: holds a larger cross-section than a half-round gutter of the same nominal width, so it carries more water on a large roof
- Valley gutter: sits in the internal angle where two roof slopes meet, collecting and concentrating the water from both - harder to inspect than an eaves gutter, so a blockage there is more likely to send water into the building rather than over an open edge
At the downpipe
- Swan neck (offset): bridges the gap between the gutter outlet at the eaves and the downpipe fixed to the wall below
- Pipe clip: fixes the downpipe to the wall at intervals, carrying its weight and the wind load on an exposed run, and keeping the socket joints aligned
- Push-fit sockets: downpipe joints are usually left push-fit rather than solvent-welded, for the same reason gutter joints are - so the plastic can expand and contract without splitting
- Shoe: fitted at the foot of the downpipe to direct the discharge into a gully, clear of the wall
- Hopper head: gathers the flow from more than one pipe or gutter at high level into a single downpipe below
Keeping debris out
A leaf guard or balloon grating fitted at a gutter outlet, or a first-stage filter fitted before a storage tank, stops leaves and grit blocking the downpipe or fouling stored water. It reduces blockages; it does not remove the need to clear the system periodically.
Materials
- PVCu (uPVC) is the standard material for domestic gutters and downpipes: light, low-cost and it does not rust, though it expands and contracts noticeably with temperature
- Cast iron and aluminium give a traditional appearance suited to period properties; cast iron is far heavier than plastic and needs correspondingly strong fixings
Rainwater and the wholesome supply
Keep harvested rainwater separate from drinking-water pipework, including where a roof downpipe fills a garden butt. A direct connection could let a fall in mains pressure draw stored rainwater into the wholesome supply. Return the butt's overflow to the drain instead.
Discharge points
- Where a downpipe discharges onto a lower roof and more than 25 square metres of upper-roof effective area drains through it, a distributor pipe is fitted to the shoe to spread the flow so it does not over-top the receiving gutter
- A soakaway taking roof water is sized for the area draining to it and sited on ground permeable enough to accept the water, at least 5 metres from a building or road