NZ Certifying Drainlayer key terms

The main New Zealand statute governing building work. It sets out when building consent is needed, who may carry out and certify restricted building work, and the duties of owners, builders and building consent authorities.

The performance requirements in Schedule 1 of the Building Regulations 1992. Drainage work must satisfy clauses G13 (foul water), G14 (industrial liquid waste) and E1 (surface water), among others.

Formal approval from a building consent authority to carry out the building work shown in the approved plans and specifications. Drainage must be installed as consented and inspected before being covered in.

A registered drainlayer holding a current certifying endorsement from the Board, allowing them to certify that drainage work they design or carry out complies with the Building Code and the consented plans.

A person registered with the Plumbers, Gasfitters and Drainlayers Board to carry out drainlaying. Registration is a legal requirement before doing drainlaying work for other people.

The statutory body that registers and licenses plumbers, gasfitters and drainlayers, sets competency requirements, investigates complaints and disciplines practitioners. It also publishes licensing classes and certifying endorsements.

A territorial authority or private organisation accredited to issue building consents, carry out inspections and issue code compliance certificates for building work, including drainage work.

A certificate issued by a building consent authority at completion confirming that the building work, including drainage, complies with the building consent and the Building Code.

The joint Australian and New Zealand standard for sanitary plumbing and drainage. It gives design, installation and testing requirements that drainage work is normally expected to follow alongside the Building Code.

A written statement, usually from a designer or installer, that certain work has been done to a stated standard. Consent authorities use it as evidence when deciding whether to inspect or issue certificates.

A drawing or record showing the drainage as it was actually installed, including positions, levels, pipe sizes and materials rather than the original design. It is given to the owner and council at completion.

The system of pipes and fittings that carries sewage and other liquid waste from buildings to a public sewer or on-site treatment system. It must be graded and vented to keep gases out of buildings.

Pipes, channels and grated inlets that collect stormwater from roofs, paved areas and ground and carry it to a stormwater system or watercourse. It is kept separate from foul water.

The slope of a drain, written as a ratio such as 1:60 or as a percentage. The correct fall lets liquid and solids travel at a self-cleansing speed without the pipe scouring too fast.

The minimum flow speed needed to keep solids moving and stop sediment building up in a drain. It is typically about 0.6 to 0.7 metres per second, depending on the pipe size and standard used.

The height of the inside bottom of a pipe at a given point, usually measured relative to a chosen datum. Invert levels set the fall of a drain and are recorded on plans and as-builts.

The distance from the finished ground surface down to the top of the pipe. It must be sufficient to protect the pipe from traffic loads and damage and to meet the minimums in the standard.

The point where a private drain joins the public sewer or stormwater main, usually near the property boundary. It needs the network operator's approval and its position and level must be recorded.

A trapped, grated fitting that receives waste water from fixtures such as sinks, basins and laundry tubs. It holds a water seal that stops sewer gases escaping into the building.

The body of water held in a trap that seals out sewer gases. Design and venting must keep the seal intact and within the depth limits set in AS/NZS 3500.2.

An access fitting such as a rodding eye or inspection opening that allows drains to be cleaned and examined. It must stay accessible and be positioned where the standard requires.

A pipe that admits air into the drainage system so trap seals are not siphoned away. It also releases foul gases above roof level, clear of windows and other openings.

A one-way valve that lets flow leave the site but stops sewage or stormwater flowing back in, protecting the building when the public system surcharges or floods.

The material placed under and immediately around a pipe to support it evenly along its length. Correct bedding spreads loads, protects the pipe and lets it hold the designed gradient.

A number describing how well a buried pipe resists deflection under load, written as SN followed by a value. The stiffness needed depends on burial depth, soil type and traffic loading.

A push-fit joint in which a rubber ring held in a groove forms a watertight but slightly flexible seal between two pipes. It allows small movement and is common on uPVC drains.

Support such as timber, hydraulic props or trench shields placed against the walls of an excavation to stop it collapsing onto workers, used where the sides are not battered back safely.

The material placed back into the trench after the pipe is laid, bedded and tested. It must be put in and compacted in layers so the pipe is not damaged or pushed out of shape.

Removing groundwater or surface water from an excavation so the trench stays dry and stable. Methods include sumps, pumps and wellpoints, with the water discharged to an approved place.

Finding existing pipes, cables and ducts before digging, using plans, locating equipment and trial holes. In New Zealand plans are usually requested through beforeUdig and services marked on site.

A test in which a completed section of drain is filled with water and checked for leakage or loss of head. It proves joints and pipes are sound before the trench is backfilled.

A test in which a drain or stack is pressurised with air and the pressure drop measured to show it is airtight. It is quicker than a water test but needs careful safety controls.

Recording the inside of a drain with a camera on a push rod or crawler to find defects such as cracks, roots, offsets and sagging. It may be required before handover or before repair work.

A check that a flexible buried pipe has not been squashed out of shape, done by pulling a mandrel or laser through it after backfilling. Too much deflection means the pipe or bedding must be redone.

Liquid waste from commercial or industrial processes that is not ordinary domestic sewage. It usually needs pre-treatment and a written consent from the network operator before entering the sewer.

A chamber that slows kitchen or food-processing waste water so fats, oils and grease float and are held back while clearer water flows on. It must be correctly sized and emptied regularly.

A system that treats and disposes of wastewater from a property not connected to a public sewer, typically a septic tank or aerated treatment unit followed by a disposal field.

An enclosed or partly enclosed space not designed for people, with restricted entry, that may contain a hazardous atmosphere. Entry requires a permit, gas testing and a standby person.

A document for a job that identifies hazards, sets out the controls to manage them and records who is responsible. It is updated as the work changes and used to brief workers and visitors.