Acceptable Solution B1/AS1

The first Acceptable Solution for clause B1 Structure (known as Acceptable Solution B1/AS1 or simply B1/AS1) is a prescriptive design solution for various types of simple structures that provides step-by-step guidance to achieve compliance with the Building Code.

Like Verification Method B1/VM1, Acceptable Solution B1/AS1 references, modifies and adds to several existing standards. However, as a prescriptive solution, it lacks the design direction of the Verification Method and primarily references standards that describe the correct use and installation of building components, materials and systems.

In July 2020, the standards and other documents referenced (in whole or in part) by Acceptable Solution B1/AS1 were:

  • AS/NZS 1170 Structural design actions Parts 0, 1, 2 and 3

  • AS/NZS 2032:2006 Installation of PVC pipe systems
  • AS/NZS 2033:2008 Installation of polyethylene pipe systems
  • AS/NZS 2566:2002 Buried flexible pipelines Parts 1 and 2
  • NZS 3604:2011 Timber-framed buildings
  • NZS 4223 Glazing in buildings Parts 1, 2, 3 and 4
  • NZS 4229:2013 Concrete masonry buildings not requiring specific engineering design
  • NZS 4251.1:2007 Solid plastering – Cement plasters for walls, ceilings and soffits
  • NZS 4299:1998 Earth buildings not requiring specific design
  • AS/NZS 4671:2001 Steel reinforcing materials
  • NASH Standard Part 2: May 2019 Light steel framed buildings

Foundations for houses built on ground that has the potential for liquefaction or lateral spread are outside the scope of B1/AS1.

Amendment 10 to Acceptable Solution B1/AS1 in 2011 stated that the Acceptable Solution could no longer be used for foundations on ground prone to liquefaction or lateral spreading in the Canterbury region. From 29 November 2021, Amendment 19 extended the effect of Amendment 10 to cover the whole country.

Buildings on this type of ground will require more-robust foundations than before and will have to use a Verification Method or Alternative Solution for building consent. The definition of ‘good ground’ in Building Code clause B1 Structure has been amended.

You can find more information on MBIE’s Building Performance website.