NZMRM working in Standards development.

In previous articles we have discussed the role Standards play in providing a framework for regulation of all sorts of products, systems, safety in many industries, and specifically how it does this for the building industry. Standards NZ have covered the new relationship with MBIE, and its transformation from a stand-alone service provider to being a business unit within MBIE. 

We have discussed the quite large number of Standards, NZ, Australian and joint and some ISO, which cover the materials and systems we use in producing roofing systems which comply and which comply with the NZBC.

In this final article we will cover the Standards in which NZMRM Technical Committee members have been involved, and discuss where these are at.  Participation may be as a member of a Standards Committee, or by submitting into the Public Comment process, (which can be as effective in bringing comment to the Committee as being on the Committee itself – and with less restraint).

I have previously discussed the difference between NZ and Australian standards committees.  

In NZ, a committee is set up for a specific project.  Once is has been decided (now by MBIE) that a new Standard is needed, or an existing one needs to be revised or amended, then committee members representing various organisations are nominated by these organisations. Once the project is completed the committee is disbanded.

In Australia, various standing committees exist over some (sometimes many) years and these cover a range of apparently related standards. Members come and go, but there is a continuing core of people who can remember the past.  

We have served on both types, and both have benefits and disadvantages. Overall the standing committee has the benefit of covering several related standards, and of some continuity of membership.

A - Standards we have worked on as committee members

NZS 3604 - Timber framed buildings -

(restricted to 10m maximum height i.e. residential or light commercial buildings) 1999-2000 completed in 1999 and amended in 2000; and 2009-2011, completed in 2011. This is the primary NZ standard affecting all residential and smaller commercial building construction and is effectively a very large Acceptable Solution, compliance with which is regarded as complying with the NZBC.

In 1999 we only became involved in the final stages of development of the Standard, and MRM’s primary concern was the specification of purlin and batten fasteners where we were able to achieve what we regarded as a more practicable outcome, which was published (with some other changes) in 2000 as Amendment 1.  

In 2009 we were involved from the beginning and contributed in a  number of areas.  

A primary concern of the committee was the strength classification of timber caused by significant degradation of pinus radiata quality in the intervening 10 years and we now have three strength grades.  Here the previous single grade was classified as the lowest, and there are now two grades above this – with the strongest having limited availability.  (All the more reason to use steel framing!)

Other concerns were with durability and location of fasteners and the corrosion zones in which materials are used (different to those for external materials), and at a late stage the assessment of ground stability (following the Christchurch earthquakes, after which it became clear that the previously used zoning was incorrect.)

NZS 2295 Permeable pliable building underlays

(i.e. does not include foil underlays or other vapour checks/barriers) 2005-2006 (Chair) and 2016-2017 completed in 2017.

In 2006, this was a belated update to the 1988 version, which was in itself derived from a 1972 British Standard. We had instead been using and calling up relevant bits of AS/NZS 4200.1 1994 (see following) as being more up to date, but 4200.1 did not properly cover permeable underlays, which are the predominant product in non-industrial buildings in New Zealand.  So the 2006 version was a complete revision of tests and specification, and allowed the inclusion of synthetic wall underlays, which by then were in wide use and not covered by any Standard. It still only provided for kraft based roof underlays.

In 2017, NZS 2295 was amended to include provision for synthetic roof underlays, by now in wide use and widely accepted as an Alternative Solution to the NZBC.  This is now ahead of 4200.1.

AS and AS/NZS Committee BD-058 Thermal Insulation

AS/NZS 4200.1 Pliable building membranes and underlays – Material

(includes foils used as vapour barriers, or thermal insulation, or lighting improvement – not used for residential in NZ) Revision, completed in 2017, but while including and specifying for permeable underlays, and covering the permeability of synthetic underlays, still does not provide for them in the duty classifications (strength).

AS 4200.2 Pliable building membranes and underlays – installation.

Not an NZ Standard but the only relevant standard in NZ or Aus.  Does include many aspects of foil installation relevant to NZ commercial buildings. Completed in 2017.  38 pages of content replacing 6 in the previous, 1994, version, and contains much information valid for New Zealand for both permeable underlays and vapour control barriers (foils.) 

AS/NZS 4859.1 Materials for the thermal insulation of buildings – General criteria and technical provisions
primarily bulk insulation, but also use of foil for insulation.  Comment only for NZMRM but relevant. Under revision currently.

Committee BD-014 – Metal Cladding AS 1562.1

Design and installation of Sheet roof and wall cladding Part 1 Metal.

NZMRM has been a member of BD-014 since 2002 when 1562.1 (then AS) was intended to become a joint standard.  Put on hold/ inactive from 2009 to 2016, then revived.  Since the advent of successive NZMRM CoPs this is less needed as a joint standard (and will still be AS only), but this remains the only Standard covering sheet roofing (Parts 2 and 3 cover corrugated fibre-reinforced cement, and plastic).  1562.1 is still under revision, but should be issued in 2018.  Some sections of this are incompatible with NZ practice, but others will be useful in NZ and will be considered in the current revision of the NZMRM CoP.

AS 4040.0 Methods of testing sheet roof and wall cladding - Introduction

AS 4040.1

Resistance to concentrated loads

AS 4040.2

Resistance to Wind Pressure for Non-Cyclone Regions

AS 4040. 3 Resistance to wind pressures for cyclone regions

The 4040 series covers the test procedures for sheet wall and roof cladding.  The methods are called up in AS 1562.1 where the outcomes to be achieved are prescribed. NZMRM broadly follows the method in the CoP Section 15, but requires different outcomes.

4040.1 covers concentrated or point load and we follow this method.

4040.2 covers Uniformly Distributed Load (UDL) created by wind uplift pressure

NZMRM follows the method but not the outcome, as 1562.1 specifies maximum deflection at which failure is deemed to have occurred and NZMRM tests to actual failure.  We are currently determining what alignment there is between these criteria.  4040.2 is currently under review of a few points.

4040.3 covers testing in cyclone regions

(there are none in NZ but these are Zones C and D in Australia; roughly north of Brisbane where tropical cyclones are likely to occur) and is about to be significantly changed.  Currently, there are two different test programmes in this Standard (4040.3 for WA and Qld, and DABM for NT) and neither of these is considered to reflect real-life experience.  In the mid-2000s BD-014 considered it necessary to revise the test programme, and the outcomes.  In 2009 a new, more realistic, regime called Low-High-Low (LHL) was introduced and mandated by the Australian Building Codes Board for compliance of roof cladding with the BCA.  Walls and doors continued to be subject to the previous regime(s).  Roof claddings in Australia for use in cyclone regions have been tested (or retested) to LHL since 2009.

Now in 2017, this is recognised and 4040.3 will include two subsections – LHL for roofs, and walls if specified; and the previous 4040.3 for walls if specified and garage and large access doors. 

AS/NZS 4505 Garage and other large access doors. 

NZMRM has an interest in panels and test processes, and provided liaison with NZ door manufacturers. Completed in 2012. Changes here were that doors were required to be type tested, which was not the case previously, and this was seen as creating some issues for NZ manufacturers.  NZMRM may be able to do some door testing for NZ manufacturers.

Committee MT-009 Metal Finishing

AS/NZS 2728 Prefinished/prepainted sheet metal

products for interior/exterior building applications - Performance requirements  describes required properties of materials used to manufacture products like those made by NZMRM members.  Reviewed in 2012-3 to include new Bluescope Australia products. We think this needs more work on durability provisions and assessment. 

Committee ME-029 

AS 3566.2 Self-drilling screws for the building and construction industries -

Corrosion resistance requirements.  Revision was sought in 2010 of the 2002 version, but lack of agreement between committee members from screw manufacturers and members from screw users during 2011-13 led to Standards Australia withdrawing the standard in 2014.  However, apart from creation of “Class 5” in the NZMRM CoP and adoption of this description, this remains the only Standard covering these products’ durability in use and the method of testing is still useful.

Other standards covered by Australian committees, including ISO liaison, which may not strictly affect NZ roofing, can still be commented on, and keeps the NZMRM name in focus.

B - Commenting using the Public Comment process.  

These are standards of which NZMRM have not been on the actual committee.  This process can still be used by committee members and all Comments are considered by the committee.

AS/NZS 3500.3 Plumbing and drainage -

Stormwater drainage – deals (inter alia) with roof drainage capacity, from profile capacity through to downpipes.  This is a very useful and relevant standard used and quoted by other standards.  NZMRM have a specific interest in changing the design restrictions on valley gutters, which are used by E2/AS1. We have submitted changes to several revisions of 3500.3 so far with no success, but have overridden the restrictions in the CoP, which is then quoted by E2/AS1.

NZS 3640 – chemical preservation of round and sawn timber

Following the “leaky building” crisis this standard was upgraded to prescribe treatment for various uses of timber. This included timbers not previously treated, such as Douglas Fir, and created a storm of comment from DF producers.  In the end the treatment process was limited to pinus radiata timber.  NZMRM’s concern was that timber treated using excessive quantities of copper was not in contact with metal roofing or wall cladding, and we were also concerned with the use of solvent based treatment in which the solvent was not completely removed.  Amended in 2013 to cover more treatment methods and to align with B2/AS1.

AS 1397 Continuous hot-dip metallic coated steel sheet and strip -

Coatings of zinc and zinc alloyed with aluminium and magnesium. This was revised in 2011 to include new Bluescope metallic coated products but initially dropped other metallic coatings used in NZ and so would have meant these were not covered by a standard. These are now included.


From all this you can see that NZMRM has had a quite long, and mostly fruitful relationships with Standards NZ and Standards Australia International. The Standards process has been well understood and existed as an independent, industry initiated, developed and managed operation outside of Government control or involvement in NZ for over 70 years.  

We now have a system of documentation of the “right way to do things” generated by those affected and those using the documentation to create better outcomes for the community of users (even if they are often unconscious of the benefits).

The Future

By the late 2000s it was clear to many that Standards NZ was not fulfilling its function as well as it could, and in 2012 a consultation process was initiated by MBIE to discuss with interested parties the way forward to increasing the use of, access to, and value of Standards in NZ.  NZMRM attended one of these sessions.

The outcome was a report by the independent facilitator recommending a number of changes to the management of Standards development. This is available elsewhere.

In earlier times it was more or less understood that Standards development, although much of the actual work was done by self-funded committee members, was not a profitable exercise but one fulfilling a useful function in society. Now it seemed that it was not fulfilling this either.

Reaction to the changes in the Building Code during the 1990s which in part allowed the construction of some inadequate or even dangerous buildings (“leaky buildings”) has resulted in more legislative controls and Government involvement in Standards.  

Following this consultation process it was eventually decided by MBIE that Standards should cease to be an independent organisation, but be included under the MBIE umbrella and managed by someone appointed by MBIE.

This took some time to bed down, during which period nothing much seemed to happen.  Our first involvement with the new system was the NZS 2295 revision/amendment. This was quite a change from earlier committees and whether this is productive in generating useful Standards remains to be seen.

During the same period, Standards Australia also became more concerned with commercialisation of Standards and the cost benefits of recommendations contained in Standards as well as the cost of producing them.


Stuart Hayman: Technical adviser to MRM