Skip to main content
HELPERG Ecosystem
Build Design HubBuild Design Hub

Building components

Drainage & Rainwater Elements

The gutters, outlets, downpipes, channels, chambers and traps that collect water, carry it and let it be inspected.

13 entries in this category.

Overview

About this category

Drainage is a chain, and a chain is only as good as the element that is currently blocked. Each element here has a distinct job — collect, admit, convey, intercept, inspect, discharge — and treating them as one undifferentiated system is what makes a blockage hard to find.

These entries name each element and what it depends on. They state no sizes, gradients, falls, capacities or rainfall figures: drainage design is a professional calculation, and this library does not perform it.

Boundaries

What this category covers, and what it does not

  • Covers the discrete elements of rainwater and surface-water drainage, above and below ground.
  • Does not cover drainage SYSTEMS — roof rainwater, siphonic, infiltration, attenuation, swale and below-ground systems are building systems.
  • Does not cover pipe, membrane or aggregate materials.
  • States no diameter, gradient, fall, capacity, rainfall intensity or discharge rate, and makes no adequacy determination.

Browse

Forms and roles in this category

Descriptive labels for what is here. They are a way of reading the list, not a filter and not a ranking.

Forms:Conveyance element
Roles:DrainageProtectionTermination

Entries

Drainage Elements components

Every entry in this category. Each explains what the element is, what it depends on, and how it relates to materials, systems and junctions.

Conveyance elementChannel Drain →A linear channel set into a surface that intercepts water running across it along a line rather than at a point.Conveyance elementDownpipe →The vertical pipe carrying water from a roof outlet down to ground level and into the drainage below.Conveyance elementGutter →A channel at the edge of a roof that collects water leaving the covering and carries it to an outlet.Conveyance elementInspection Chamber →An access point in a buried drainage run that allows the pipework to be inspected and cleared.Conveyance elementOutfall →The point at which a drainage system discharges into a watercourse, a sewer, or the ground.Conveyance elementOverflow Outlet →A secondary opening that discharges water visibly when the primary drainage cannot cope, before it accumulates.Conveyance elementPerforated Underdrain →A pipe with openings along its length, laid in a permeable surround, that collects water from the ground around it.Conveyance elementRainwater Outlet →The point at which water leaves a roof or gutter and enters the pipework that carries it away.Conveyance elementSilt Trap →A chamber with a sump below the outlet that lets solids settle out before water continues into the system.Conveyance elementChamber Benching →The shaped, falling floor formed inside a drainage chamber that carries flow across it and leaves nowhere for solids to settle.Conveyance elementGully →A point inlet set into a surface that admits surface water into a drainage system, commonly through a trap that keeps drain air below it.Conveyance elementHopper Head →An open funnel at the head of a downpipe that receives discharge from above and concentrates it into the pipe beneath.Conveyance elementRodding Eye →A capped opening that lets rods be introduced into a buried drainage run at a place where no chamber is provided.

Related reference libraries

Components are what materials become and what systems are made of. The three libraries answer different questions and are kept deliberately separate.

Materials Library →Building Systems →