ACO New Zealand


Building Code

Building Code Compliance for Threshold Drainage


Provision for level threshold drainage is called for by NZBC E2/AS1 where a concrete floor slab exits onto external paving/concrete. Channel requirements are detailed in paragraph and say that:

  • Width to suit capacity in accordance with E1/AS1
  • Minimum depth of 150mm
  • Maximum length of 3700mm
  • 1:200 minimum fall to outlet

A grate is needed to cover the channel and the specifications are:

  • Grate supported independently of door frame
  • Removable to allow access for cleaning
  • Designed to accommodate imposed loads
  • Wheelchair and mobility aid friendly
  • Continuous 12mm gap from any joinery

ACO provides a wide range of product offerings designed for use in level entry thresholds and façade drainage, where compliance with NZBC Building Code E2/AS1 is required. A variety of products are available to suit a range of applications, joinery details and site requirements, using a cast in-situ channel and a proprietary grate and frame.

Benefits of using an NSBC Building Code E2/AS1 compliant solution include easier consenting process and a simple ‘drag and drop’ specification.

NZBC E1/AS1 – Alternative Solution

An Alternative Solution, falling under NZBC E1 can also be presented where joinery and cladding allows, or where a precast channel is preferred. This is especially useful with flush finish joinery, or where a vehicle trafficked finish is required.

To assist with the design and consenting process, ACO can provide full technical support and channel hydraulics to demonstrate the suitability of the product as an Alternative Solution.

Project Consenting

The application of the building code can vary from project to project and with different council interpretations. ACO are more than happy to offer design and installation advice, for all consenting matters it is best to speak to your contact in the council.

New Zealand Building Code