1 June 2001
Weathertightness of Houses
BRANZ (the Building Research Association of New Zealand) has expressed concern at some of the recent media statements on
the weathertightness of New Zealand houses.
“Over recent days there have been many stories in the press stating that New Zealand houses leak. It is appropriate to
provide a more balanced view of the actual situation,” said Dr Graham Rowe, BRANZ Marketing Manager. “Leaks can occur in
all climates and with all types of cladding systems if buildings are not designed, built or maintained correctly.
“What causes a leak can vary, from poor detailing at the design stage, shortcuts being taken in the construction
process, manufacturers’ recommendations not being followed or materials used not being those originally specified, to
critical elements of the building – such as flashings -- being omitted. Design fashion – elements such as horizontal
parapet caps, pipes penetrating the exterior cladding, cantilevered decks and lack of or inadequate eaves, for example –
can also increase the risk of leaks. It is very rare for properly maintained cladding materials themselves to be at
fault.
“The consequences of a leak vary widely, but common problems can include decayed framing, wet insulation materials,
deterioration of interior linings and damaged flooring, as well as the formation of moulds which can be damaging to
health.
“The building industry agrees that better training is required, and has already responded with new training schemes for
builders and for specialist applicators and fixers of some proprietary cladding systems. Manufacturers, be they of
cladding products, windows, roofing or other key construction elements, are increasing their efforts to ensure they
comply with appropriate Standards and the requirements of the New Zealand Building Code, and to provide more product
information. Many continually review their products and have them Appraised by BRANZ – a process that ensures that they
are fit for their intended purpose. All building work is subject to a building consent and a sign-off at the completion
of the job through a code compliance certificate, to ensure it meets the requirements of the New Zealand Building Code.
“The industry has recently set up a national working group to deal with the issue of leaking buildings, led by BRANZ
Materials Manager Adrian Bennett. The group includes designers, builders, manufacturers, building regulation experts,
educators and industry associations. It aims to coordinate the range of activities already under way across the industry
and to identify the additional work that needs to be done to ensure that buildings in the future do not leak as some do
now.
“An initial focus will be on education and training, both for new entrants into the industry and those already working
in it. Increased research into what makes effective cladding systems for New Zealand conditions is also being
investigated,” Dr Rowe said.
BRANZ says that anyone who is concerned about the design or construction of a house they are currently planning, or the
materials being used, should ensure they clarify with their designer, builder, manufacturers and local authorities how
the weathertightness of the building is being addressed, or talk to a local building consultant for advice.
The BRANZ internet site at www.branz.org.nz includes a current list of all BRANZ Appraised products as well as contact
details for all building consultants who are BRANZ Accredited Advisers.
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For more information contact:
Graham Rowe,
Marketing Manager,
BRANZ
Tel: (04) 235 7600
or:
Adrian Bennett
Co-ordinator, Weathertightness Steering Group,
BRANZ
Tel: (04) 235 7600
The Building Research Association of New Zealand
Moonshine Road, Judgeford
Private Bag 50 908, Porirua City, New Zealand
Telephone (04) 235 7600, Fax (04) 235 6070
E-mail: postmaster@branz.org.nz