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.

Updates to the Building Code in November 2019 added to B1/AS1 the information on the design of foundations in expansive soils previously in the Simple House Acceptable Solution SH/AS1. Current Building Code solutions to ‘good ground’ in B1/AS1 will continue to comply until 28 November 2021.

Foundation designs for houses built in areas that have the potential for liquefaction, as defined by the Christchurch City Council, the Selwyn District Council and the Waimakariri District Council, may be in accordance with the MBIE guidance Repairing and rebuilding houses affected by the Canterbury earthquakes. The foundation options apply to properties in the Canterbury earthquake region that have been categorised as Technical Category 1 to 3 (TC1, TC2 and TC3).