Issue 31 – September 2011
The Department of Building and Housing (the Department) has issued two new guidance documents to support changes to the Building Code for Structure (B1).
- Guidance for NZS 3604 construction on ground with potential for liquefaction, outside Canterbury
- Guidance for an alternative solution for mesh reinforcement for concrete slabs-on-ground
The Department has issued guidance for using NZS 3604 construction on ground with potential for liquefaction, for those building outside Canterbury.
In the Canterbury earthquake region the definition of 'good ground' has been changed in Acceptable Solution (B1/AS1) to exclude ground where liquefaction and lateral spread could occur. Defining 'good ground' is complex and once the Department has more knowledge from Canterbury, it will address the definition of 'good ground' nationwide.
In the meantime, the Department has issued guidance for building designers and homeowners who are building on potentially liquefiable soils outside Canterbury, and may choose to use foundation details that provide enhanced performance over those in NZS 3604:2011 (including as modified in B1/AS1).
View the Guidance on using NZS 3604 construction on ground with potential for liquefaction (www.dbh.govt.nz/liquefaction-construction-on-ground-guidance).
The Department has issued guidance for NZS 3604 concrete slabs-on-ground.
Recent changes to Acceptable Solution (B1/AS1) require all concrete slabs constructed according to NZS 3604 on 'good ground', to be reinforced with Grade 500E reinforcing mesh. This applies nationwide.
Because Grade 500E reinforcing mesh may not yet be available in New Zealand, the Department has issued guidance providing an alternative solution using an equivalent capacity mesh as an interim measure.
View the Guidance on reinforcement for concrete slabs-on-ground (www.dbh.govt.nz/earthquake-concrete-slabs-guidance).
Summarised from the Department of Building and Housing's Building Controls Update No. 117, 22 August 2011.
- NZS 3604:2011 Timber-framed buildings