Taking the initiative in weathertightness compliance

Hebel wall systems have stood the test of time in terms of weathertightness in Australia for over twenty years. Rigorous testing, continuing system innovation, stringent quality standards and a high level of technical support for the construction industry have all contributed to this long-standing record.

What’s more the completed weathertightness verification of the Hebel external wall system to the new National Construction Code (NCC) method ensures compliance is firmly in place to assist architects, designers, builders and tradespeople.

Lessons from New Zealand

The reasons for strict weathertightness standards are compelling. Water penetration can lead to unhealthy or dangerous conditions, loss of amenity, undue dampness and deterioration of building elements. Although there have been no significant problems experienced in Australia, leaking residential buildings have haunted New Zealanders for decades following a spate of poor construction standards relating to external wall cladding in the 1990s and early 2000s. Repair and replacements costs are estimated at $11 billion nationally over a 20 year period. Victoria has had some problems with non-compliant external wall cladding and a number of warnings have been issued.

With the New Zealand crisis in mind and warnings in Victoria, the Australian Building Codes Board has taken greater steps to protect occupants in relation to weathertightness. These steps embrace recently introduced cladding systems (Alternative Building Solutions under the NCC) and traditional ‘deemed-to-satisfy’ building systems that includes masonry veneer and full masonry external walls.

Amending the National Construction Code

New inclusions on weathertightness in the National Construction Code (NCC) 2015 take effect on 1st May 2015. Hebel took the initiative to prove the weathertightness of its residential external wall system well ahead of this date. Testing was conducted at the CSIRO in Sydney in December last year using the proposed NCC Verification Methods FV1 and V2 2.1.

A two-storey Hebel PowerPanel XL external wall system prototype, categorised as a Unique Wall System, was tested. This was done under the water penetration by static and cyclic pressures test procedure in accordance with AS/NZS4284:2008 - Testing of Building Facades. The system included vertical and horizontal control joints, wall junctions at external and internal corners, a window, door, electrical box, balcony drainage and parapet flashing, the base of the wall at the slab junction and top of the wall to the eaves or parapet junction.

A new confidence

Architects and specifiers can be fully confident in documenting a building façade with this Hebel wall system, validated by testing under the NCC Verification Method. This method provides a risk matrix for designers to assess the building façade wall system against a risk factor, category and risk severity with corresponding scores. For builders and tradespeople there is greater assurance when providing a guarantee and warranty to the homeowner. For the occupants, whose main recourse for defects is through the warranty, there is the assurance of a rigorously tested system that contributes to the weathertightness of their building envelope.