*ARCHIVE* - BIA Update 30 - A new Acceptable Solution for weathertightness (E2/AS1) 23 Jun 2004

A new Acceptable Solution for weathertightness (E2/AS1) - provides better protection for homeowners

The BIA has announced changes to its Acceptable Solution for External Moisture (weathertightness), or E2/AS1.

Chairman Barry Brown said the new requirements defined good practice for the way buildings are designed and built to help overcome leaky building problems and the changes were focused on achieving better buildings for New Zealanders.

"They're aimed at providing better protection against leaks for building owners and users and they represent the best New Zealand and international thinking in building science.

"Together with the recent changes to treated timber requirements, we have now addressed two of the underlying technical causes of the leaky buildings problem. The Building Bill now before Parliament will also provide a range of measures to improve building performance for owners."

The new requirements, or Weathertightness Solution, contain much more detail and guidance for architects, builders and building inspectors on how buildings should be designed and built to prevent leaks, and to manage them if they occur.

Important Elements of the New Requirements

The underlying philosophy of the changes is the adoption of the "4Ds" principles of water management in buildings.

The 4Ds (in order of importance) are:

Deflection - that is, keeping rain away from sensitive areas by using features like eaves or flashings.
Drainage - providing "paths" for water that gets behind cladding to drain away. Drained cavities are an example of this.
Drying - removing water that leaks through a cladding and does not drain away - principally through ventilation.
Durability - making sure materials used to construct walls and roofs have an appropriate level of durability for the situation they will be used in.

The changes will apply to timber framed buildings up to three storeys or 10 metres high (this includes most standard houses and low rise apartment buildings). Other key elements of the changes are: 

• The introduction of a risk management approach to weathertightness management. That is, the more at risk a building is of leaking (based on a range of factors like complexity of design and exposure to wind), the greater the level of protective features required.
• Much more detail around the design of moisture protective features like flashings and cappings for parapets. 
• A wider range of cladding systems are covered:

Claddings covered in old Solution	Claddings covered in new Solution
Wall Claddings - Brick veneer - Timber weatherboards - Stucco	Wall Claddings - Brick veneer - Stucco - Timber weatherboards - Fibre cement weatherboards - Profiled metal - Fibre cement sheet - Plywood sheet - EIFS Roof Claddings - Butyl/EPDM membranes - Concrete/clay tiles - Pressed metal tiles - Profiled metal

• Reinforcing the need for drained cavities in a wider range of building situations as well as detail on how these should be built.
• More detail around designing problematic areas like decks, balustrades and balconies.
• The need for installers who are approved by the supplier or manufacturer for most claddings in the Acceptable Solution.

The BIA has also introduced a new Verification Method (E2/VM1) to allow cladding manufacturers to prove the weathertightness performance of their products when used as part of an overall cladding system.

Timing of Changes

The BIA has announced a staged implementation of the changes: 

• The changes will apply to projects where consents are applied for from 1 February 2005. The intention of this date for implementation is to give councils, private building certifiers and industry an opportunity to put in place any operational changes required to successfully implement the new Acceptable Solution.
  
• The current E2/AS1 remains effective until 31 January 2006 for buildings which have building consents issued on the basis of the current E2/AS1. The intention of this is to ensure owners who have received consents under the existing requirements have an opportunity to finish their projects and receive code compliance certificates. 

These dates are subject to final feedback from the sector. This feedback is about ensuring there are no significant unforeseen operational issues that would make the 1 February 2005 implementation date impractical.

Those wishing to make comment on the implementation date please email comments to comments@bia.govt.nz with 'E2/AS1 Implementation Date' in the subject line.

Impact of Implementation Arrangements on Territorial Authorities

These arrangements mean: 

• Territorial Authorities can issue building consents based on the new E2/AS1 when it becomes effective on 1 February 2005 (for applications received by them on or after 1 February 2005), and for these consents can issue code compliance certificates using the new E2/AS1.
  
• The current E2/AS1 can be used to issue building consents until 31 January 2005 and code compliance certificates until 31 January 2006 for buildings which have building consents issued on the basis of the current E2/AS1. Buildings complying to the current E2/AS1 within those parameters are deemed to comply with the Building Code.
  
• Territorial Authorities must have reasonable grounds for being satisfied that a building complies with the Building Code in order to issue building consents or code compliance certificates. Even though a building does not comply with an Acceptable Solution, territorial authorities can still issue a building consent or code compliance certificate where an Alternative Solution is used. Territorial authorities must consider each building on its merits.
  
• Our strong advice to Territorial Authorities is that they clearly inform their customers of the changes to the Acceptable Solution and the implications for their building project. 

Impact of Implementation Arrangements on Private Building Certifiers

These arrangements mean: 

• Private building certifiers will not be able to issue building certificates or code compliance certificates based on the new E2/AS1 until after 1 February 2005.
  
• The current E2/AS1 can be used to issue building certificates that territorial authorities rely on to issue building consents, provided that the building consents are issued before 31 January 2005. The current E2/AS1 can also be used to issue building certificates or code compliance certificates until 31 January 2006 for buildings which have building consents issued on the basis of the current E2/AS1. Buildings complying to the current E2/AS1 within those parameters are deemed to comply with the Building Code. Wall claddings covered by the current E2/AS1 are brick veneer, timber weatherboard and Stucco. 

A New Verification Method

The BIA also announced today a new Verification Method for Clause E2 of the Building Code (E2/VM1).

This introduces a verification testing method to allow cladding manufacturers to prove the weathertightness performance of their products when used as part of an overall cladding system containing a cavity. This provides another route for manufacturers to prove compliance of their systems with Clause E2 External Moisture.

Existing systems may have been tested to early versions of the Verification Method, and manufacturers of these systems should talk to their testing laboratories to see if their testing is sufficient to establish compliance with the Building Code.

The new E2/VM1 is effective from 1 July 2004.

Detail of Amendments

These changes are significant and it is important that building officials, designers, builders, manufacturers and others involved in the industry understand them.

The full documents are available from our publisher, the Victoria University Book Centre. To order, visit their website at www.bookcentre.co.nz or phone 0800 370 370.

Further information

An introduction to the changes, entitled Introduction to External Moisture, is available via the homepage (media release) of the BIA website: www.dbh.govt.nz

BRANZ and the BIA are running a comprehensive introductory seminar on the changes, throughout the country. Details can be found on the BRANZ website: www.branz.co.nz 

Visit the BIA website to learn more about the changes:

Questions: contact the BIA on (04) 471 0794 or freephone 0800 242 243.