Contractor (September 2011) A Concrete Solution to a Leaky Problem

01 Sep 2011

Rob Gaimster
Cement & Concrete Association of New Zealand (CCANZ)

With New Zealand Building Code documents now referencing CCANZ’s weathertight concrete construction Code of Practice, the issue of leaky homes has regained some prominence on a building and construction industry agenda dominated by the Canterbury earthquakes.

The vast majority of attention within the industry is currently, and appropriately, focussed on concerns surrounding Christchurch, and its rebuilding.  This has been even more apparent since the release of the draft Central City Plan in mid-August.

While it is paramount to address issues of land use and appropriate design as they relate to building performance during earthquakes, it wasn’t too long ago that the leaky homes crisis dominated industry discussions.

The launch of the leaky homes Financial Assistance Package at the end of July brought the issue of weathertightness back into focus, and the numbers remain shocking.

It is estimated that more than 80,000 people are living in leaky homes, predominantly built between 1992 and 2005.  In the greater Auckland region alone, the council predicts a total number of claims around the 15,000 mark.  Nationwide the cost of repair will be approximately somewhere between $11 – $50 billion.

Under the Financial Assistance Package, eligible homeowners will receive a 25 percent contribution from the Government and may receive 25 percent from their local council. The contributions will be based on agreed actual repair costs.

Homeowners will need to meet a range of criteria to qualify for the Financial Assistance Package, including having an eligible claim as defined in section 8 of the Weathertight Homes Resolution Services Act 2006, and having an assessor’s report under the Weathertight Homes Resolution Services Act 2006.

Qualifying claimants will also need to demonstrate they can pay their share of the repair costs, as set out in an agreed repair plan taking into account the amount that will be contributed by the government and any participating local council.

Eligible home owners who use the scheme must agree not to sue contributing councils and the Crown, although they can still pursue other liable parties such as builders, developers and manufacturers of defective products.

The government’s 25 percent contribution towards agreed repair costs is expected to cost a massive $1 billion over five years.

It is timely, therefore, that building a home to take advantage of concrete’s excellent weathertight credentials has become even simpler with a new Acceptable Solution that references the CCANZ’s Code of Practice CCANZ CP 01:2011.

From August 2011 Clause E2 (External Moisture) of the New Zealand Building Code gained an Acceptable Solution  (E2/AS3) for weathertight concrete and concrete masonry construction that references CCANZ’s Code of Practice for Weathertight Concrete and Concrete Masonry Construction.

The Code of Practice covers the weathertightness of the building envelope for concrete slabs on the ground, concrete walls and associated methods of insulation, concrete flat roofs and decks, and concrete to timber construction junctions. 

To aid planners and builders, the Code of Practice follows the same format as existing weathertightness solutions, but offers larger detail drawings following the text.

CCANZ developed the Code of Practice in partnership with building and construction industry representatives, and its acceptance into the New Zealand Building Code followed wider consultation by the Department of Building and Housing (DBH).

Needless to say, I am delighted with the Code of Practice and believe it will bring real benefits to builders and home owners.

The document’s development and its inclusion as an Acceptable Solution in the New Zealand Building Code will alleviate the current uncertainty amongst consent authorities in the area of weathertight concrete and concrete masonry design and construction.

It will also allow builders, designers and their clients to choose from a wider range of building materials, and in turn enable the weathertight and rot resistant advantages of concrete and concrete masonry systems to enhance New Zealand’s building stock.

The establishment of E2/AS3 in the NZBC, along with the launch of the leaky homes Financial Assistance Package, has placed a degree of the building and construction industry spotlight back on to the weathertightness issue, which those rebuilding Christchurch would do best to take into account.

For further information about this key change to the NZBC External Moisture documents, go to the Department of Building and Housing website -

To download [pdf 2.80 MB] or purchase a hardcopy of Code of Practice for Weathertight Concrete and Concrete Masonry Construction (CP 01:2011), go to the CCANZ website -

Article appeared in Contractor magazine.