Masterspec
13 Sep 2021
THE HISTORY OF MASTERSPEC
Construction Information Limited (CIL) is a New Zealand owned and operated industry organisation incorporated in 1995 to manage and create information...
09 Sep 2021
THE BEST WAY TO COLLABORATE THROUGH MASTERSPEC
There’s nothing quite like the peace of mind of a professional, well-thought-out specification. Build quality specifications in Masterspec with...
31 Aug 2021
SPECIFYING SCNZ STRUCTURAL STEEL ON MASTERSPEC
Structural Steel New Zealand (SCNZ) has had a Structural Steel specification document based on AS/NZS 5131 since 2018. However, a new industry...
04 Aug 2021
PURLINS & GIRTS MOVING DAY
Masterspec existing branded Purlin and Girt sections are on the move, but not far. For a long time they have not quite been in the right CBI number,...
04 Aug 2021
CONCRETE TERMINOLOGY & TYPES
With three new branded sections relating to concrete, we have provided a brief overview article describing common concrete terminology and related...
03 Aug 2021
MONTHLY PRODUCT PARTNER EVENTS AT MASTERSPEC
Partner Manager Trish Croot is excited to introduce a brand new, monthly networking opportunity to Masterspec Partners. Join us at the Masterspec head...
03 Aug 2021
mDOCS, BE A PART OF GROWING TECHNICAL RESOURCES FOR THE INDUSTRY
mDocs technical library is a free resource within your subscription that will help ensure the entire specifying community has the right documents, at...
03 Aug 2021
WHY INCLUDE THE WARRANTY AGREEMENT FORM?
The Masterspec section 1237WA WARRANTY AGREEMENT is a blank, standard form of a warranty agreement, available in all Masterspec systems except Minor...
02 Aug 2021
MASTERSPEC'S HELPDESK FOR SPECIFIERS AND PARTNERS
Are you a designer that’s creating a specification and have a quick question? Or maybe you are a Masterspec Partner and need some direction on where...
20 Jul 2021
NEW PRODUCT PARTNER SECTIONS FOR JULY 2021
In case you missed our Masterspec NOTES at the beginning of the month, here is a list with reference links for the new work sections published for...
29 Jun 2021
NEW GENERIC WORK SECTION - 5517 BENCHTOPS
Masterspec are happy to announce a new generic section, 5517 Benchtops, that encompasses the specification of a broad range of benchtops across...
29 Jun 2021
2391 RE-LEVELLING FOUNDATIONS & FLOORS - A NEW GENERIC SECTION
This new Masterspec section 2391 RE-LEVELLING FOUNDATIONS & FLOORS relates to the repair and re-levelling of existing foundations and floors of small...
03 Jun 2021
HOW MUCH DOES MASTERSPEC COST?
With seven different libraries to choose from, Masterspec has all you need to create a quality, New Zealand construction specification for any design....
11 May 2021
NEW PRODUCT PARTNER SECTIONS FOR MAY 2021
In case you missed our Masterspec NOTES at the beginning of the month, here is a list with reference links for the new Product Partner work sections...
29 Apr 2021
BUILDING CODE UPDATES 2020-2021 - INTERNAL MOISTURE
On the 4th November 2021, the changes to NZBC E3/AS1 and the addition of E3/AS2 become the Acceptable Solutions for Internal Moisture. But it is...
29 Apr 2021
LIST OF WORK SECTIONS WITH NZBC CHANGES - MAY 2021
With the updating of the Masterspec libraries, we thought it may be useful to provide the complete list of work sections that have been updated so you...
28 Apr 2021
BUILDING CODE UPDATES 2020-2021 - TIME TO ABSORB & APPLY
On the 3rd of November 2021, the 12 month transition period ends for the NZBC changes introduced in November 2020. This means the previous editions of...
28 Apr 2021
PROTECTION FROM FIRE UPDATES
This article delivers a summary of a number of the more significant updates to C/VM2 and C/AS2. Minor amendments to C/VM1 and C/AS1 were also made,...
28 Apr 2021
STORMWATER DRAINAGE DESIGN – NEW OPPORTUNITIES IN NZBC E1 NOVEMBER 2020 UPDATE
November 2020 brought a number of updates to the Building Code, including a new Acceptable Solution in the form of E1/AS2 in its newest version,...
25 Mar 2021
UPDATES TO MASTERSPEC INTUMESCENT PAINT – STEELWORK SECTIONS
Late last year the FPANZ (Fire Protection Association of New Zealand) released the Code of Practice COP-03 Version 1.0, Specification of Application...

STORMWATER DRAINAGE DESIGN – NEW OPPORTUNITIES IN NZBC E1 NOVEMBER 2020 UPDATE

28 Apr 2021

November 2020 brought a number of updates to the Building Code, including a new Acceptable Solution in the form of E1/AS2 in its newest version, Amendment 11. Designers and specifiers now have the opportunity to use AS/NZS 3500.3 (with modifications) as an Acceptable Solution for stormwater drainage systems. Both E1/VM1 and E1/AS1 contain a number of sundry corrections and updates, while E1/AS2 is presented as a series of modifications to specific clauses in AS/NZS 3500.3.

Other notable updates to E1/AS1 include replacing the rainfall intensity maps with an extensive table of data for numerous specific locations throughout New Zealand. This gives designers the choice of either using these figures, or data from the relevant Territorial Authority. E1/AS1 also provides a comment that, where discrepancies are found, the most conservative intensity figure should be used. No definition of 'conservative' is given, but it would be prudent to err on the side of caution and assume the higher intensity prevails. This comment is also given in E1/VM1.

The rainfall intensity data is based on information produced by the National Institute for Water and Atmospheric Research (NIWA), and is also available online from their High Intensity Rainfall Design System (HIRDS) which provides estimates for any location in New Zealand. Note that Annual Exceedance Probability (AEP) also now appears in the definitions, to link in with its use in AS/NZS 3500.3 (particularly where a more onerous 2% AEP is to be used for overflows, internal gutters and valley gutters). In addition, internal gutters now have a minimum width of 300mm, and 30mm minimum freeboard, tying in with E2/AS1.

Returning to the new Acceptable Solution E1/AS2, MBIE listed the following goals during the consultation period:

  • Increase ‘deemed to comply’ options for sizing and designing roof gutters and surface water drainage systems 
  • Introduce new ‘deemed to comply’ design and installation solutions for:
    • on-site stormwater detention systems (partial solution)
    • pumped stormwater systems
    • siphonic roof water drainage systems
  • Introduce informative installation provisions for subsoil drainage systems 
  • Provide ‘deemed to comply’ design and installation solutions for surface water and roof water drainage systems that fall outside the scope of the current Verification Method and Acceptable Solution 
  • Allow for consenting efficiency when stormwater drainage systems are designed using AS/NZS 3500.3:2018 as the design would no longer need to be treated as an Alternative Solution by Building Consent Authorities.

Of these goals, OSDs, pumped stormwater systems and siphonic roof drainage became informative only, as applicable to New Zealand. Upon publication, MBIE stated that the purpose of E1/AS2 is "to cover larger sites and designs that were previously considered Alternative Solutions". E1/AS2 makes a number of amendments to AS/NZS 3500.3, which must be read in conjunction with the Standard in order to comply with this new Acceptable Solution.

The calculation procedures set out in the Standard are more detailed than those in E1/AS1, and can enable deemed-to-comply solutions that were previously only possible as Alternative Solutions.  Additionally, more accurate sizing of rainwater goods is possible thanks to the ability to use the NZMRM Capacity Calculator, which is closely aligned with the methods set out in AS/NZS 3500.3.

Among the areas that the Standard assists with more accurate designs, is roof catchment areas. Whereas E1/AS1 lists a variety of areas and roof pitch ranges (up to between 200m2 and 350m2 depending on pitch), AS/NZS 3500.3 gives multiplication factors for any given roof plan area, and also considers the direction of wind-driven rain, as well as multiple roof slopes into a common gutter, to arrive at more accurate sizing for rainwater goods.

Whilst larger buildings can now be designed within the scope of E1/AS2, it should be borne in mind that AS/NZS 3500.3 (as modified by E1/AS2) does in itself have limitations in its scope; namely gutter, outlet and downpipe capacity which are generally limited in range to between 3 and 16 litres per second. Roof drainage designs outside this range should be proven by calculation as an Alternative Solution.

Masterspec sections

Masterspec sections ranging from flat roofing systems to above- and below-ground stormwater to backfilling have all been updated in response to this update. Where sections previously cited AS/NZS 3500.3 as an Alternative Solution, these now offer compliance via this Standard as modified by NZBC E1/AS2. Compliance clauses have been split to differentiate between AS1 and AS2, so that specifiers, contractors and Building Consent Authorities can clearly see which Alternative Solution has been followed. All updated Masterspec sections have been published on 1st May for immediate use.

At the same time, 7112 Rainwater Storage Tanks section has been updated and expanded, to widen the scope of its application. The section has been renamed to enable the specification of tanks for storing water from a wide range of sources, and for various uses. Clauses and guidance for potable and non-potable water use have been included, and a new clause has been created for hybrid retention/detention tanks.

In addition, 7455 Stormwater Soakage Systems has been similarly updated, again renaming the section to include new clauses for above- and below-ground detention tanks. Both 7112 Water Storage Tanks and 7455 Stormwater Mitigation Systems are available in Standard, Structural & Civil, Services, Landscapes and Basic.

NZBC E1 Amendment 10 continues to be operative until 3rd November 2021, while Amendment 11 became operative on 5th November 2020 and becomes compulsory on 3rd November 2021.


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