Constructing cavities for wall claddings

All content related to E2 External moisture

About this document

  • Of interest to Building consent authorities, Builders
  • ISBN: 0-478-29722-X (Print) / 0-478-29723-8 (Online)
  • 1st edition


A practical and easy-to-follow guide that explains how to construct drained and vented cavities for timber-framed buildings to ensure they are well built and healthy. It is targeted for people involved in design, construction and weathertightness compliance.


For timber-framed buildings in New Zealand, recent science and research has identified ‘drainage’ and ‘drying’ of water as critical functions of cavities.

This booklet will help you construct cavities according to E2/AS1 to help ensure buildings are well built and healthy. Note that E2/AS1 is amended from time to time, and the most recent version of E2/AS1 should be referred to for compliance with the Building Code.

It sets out the importance of designing for weathertightness, including:

  • when cavities are needed
  • installing wall underlays
  • cavity battens
  • closing off the top cavity
  • drainage and ventilation
  • cavity walls over two storeys
  • installing window and door joinery
  • air seals.

Note that it does not explain the cavity behind masonry veneer wall claddings.

All guidance documents related to E2 External moisture

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: