Issue 01 - October 2011
There have been several changes to the documents supporting Building Code Clauses B1 Structure and E2 External Moisture. If you are a designer or builder of timber, steel framed or concrete houses and small buildings, these changes affect you.
Changes to the documents supporting B1 Structure
If you use Acceptable Solution B1/AS1 and NZS 3604 to construct houses and small buildings you should use the 2011 version of NZS 3604; that's the version B1/AS1 references now.
But there are important modifications to NZS 3604:2011 in B1/AS1:
You can't use unreinforced concrete slabs-on-ground anywhere. All concrete slabs-on-ground must be reinforced with Grade 500E steel mesh which is tied to perimeter foundation reinforcement. This was introduced for the Canterbury earthquake region in May 2011 and has been extended nationwide. Read guidance on reinforced concrete slabs-on-ground.
In the Canterbury earthquake region the definition of 'good ground' excludes ground with potential for liquefaction or lateral spread.
You can buy NZS 3604:2011 from the Standards New Zealand 
website.
If you use Verification Method B1/VM1 there are two new referenced documents:
A Standard for restraining equipment in earthquakes – NZS 4219:2009. Visit the Standards NZ website to buy this standard.
A Standard for the design of light-steel framed houses, published by the National Association of Steel-framed Housing (NASH). Visit the NASH website to buy the standard.
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Changes to the documents supporting E2 External Moisture
Acceptable Solution E2/AS1, which deals with the weathertightness of cladding, has been updated to work better with the 2011 version of NZS 3604. The extended wind range of 55m/s allows more buildings to be designed to E2/AS1.
Verification Method E2/VM1, is a way to test how claddings with drainage cavities perform on timber-framed buildings to show that they comply with the Building Code clause E2. E2/VM1 has been updated to work with the revised E2/AS1.
There is a new Acceptable Solution for weathertightness of concrete and concrete masonry construction. This is E2/AS3 which references the Code of Practice for Weathertight Concrete and Concrete Masonry Construction published by the Cement and Concrete Association of New Zealand (CCANZ). Read the CCANZ document .
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When do B1 and E2 changes take effect?
They are already in effect.
There is a transition period until the end of January 2012 when you can use either the previous documents or the new ones. From 1 February 2012 onwards you must follow the revised documents to be sure your buildings will comply with the Building Code.
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