Basement Design Guide

Building on the success of the Code of Practice for Weathertight Concrete and Concrete Masonry Construction (CP 01: 2014), CCANZ has published Concrete and Concrete Masonry Basement Design Guide (BG 01:2016).

The Guide is intended as an overview to inform the initial design process for underground structures. It covers the use considerations for basements and site characteristics, describes suitable design methods, and discusses the selection of materials.

New Zealand is undergoing a demographic transformation. The population is aging, immigration patterns are changing, and couple and single person households are increasing,” says CCANZ Chief Executive Rob Gaimster.

Add to this rising property prices, the scarcity of land for development, plus the relatively slow rate of residential construction and we are seeing significant growth in medium density developments and therefore basement construction.

Basements maximise available land space by creating storage for household items or unappealing and possibly noisy plant equipment or waste collection, all without increasing the building footprint or occupying additional land,” says Rob.

It is imperative that during the planning stages of a basement all factors are accounted for. This Guide will be a valuable tool in helping designers meet their objectives.

The Guide will provide solutions for a watertight below ground concrete structure across four separate categories, each requiring different levels of watertightness:

  • Basic plant rooms and refuse collectors - minor seepage and patches accepted.
  • Dry plant rooms, high spec car parks and work shops - no seepage but moisture vapour accepted.
  • Ventilated areas such as retail storage and restaurants - dry ambience.
  • Controlled ventilated areas: residential, offices and archives - totally dry and thermally insulated.

Special attention will also be given to soil-type, with different watertight solutions recommended depending on whether the soil is, for instance, self-draining or if ground water is present. Solutions will cover watertight concrete, cavity draining build ups and membrane options.

Concrete and Concrete Masonry Basement Design Guide (BG 01:2016) can be downloaded from the CCANZ website.