Weatherproofing External Cladding

Introduction

As a leading supplier of metal claddings in Australia, Fielders® maintains a strong commitment to compliance of its products to relevant Australian Standards, building and design codes and other statutory requirements.

This bulletin summarises the position of Fielders® roof and wall claddings with respect to the weatherproofing requirements of the National Construction Code.

Context for this information

The 2019 National Construction Code (NCC) outlines both “Performance Requirements” and “Deemed to Comply” provisions for weatherproofing of metal wall claddings in:

  • Volume 1 (Multi-Res, Commercial, Industrial, and public assembly
    buildings) and;
  • Volume 2 (Residential buildings) of the NCC

This information seeks to clarify the requirements for metal claddings for each building type.

Compliance implications for Fielders® steel cladding products

This page summarises the compliance implications for Fielders® steel cladding products in three applications:

  1. Walling – non-residential
  2. Walling – residential
  3. Roofing – non-residential and residential

1. Walling – Non-residential applications

NCC Volume 1 (For Classes 2-9 Buildings) specifies the weatherproofing Performance Requirements that must be met by the wall system in non-residential applications.

Performance Requirements Section – FP1.4 Weatherproofing states that a roof and external wall (including openings around windows and doors) must prevent the penetration of water that could cause;

  • unhealthy or dangerous conditions, or loss of amenity for occupants; and
  • undue dampness or deterioration of building elements

There are no deemed-to-satisfy provisions in respect to FP1.4 for external walls for Classes 2-9 Buildings

The wall system comprises not only the metal cladding but the integrated performance of all the various features including water resistance via flashing details and sealing, moisture management via flashing and membranes, insulation, windows and door installations etc.

Fielders® does not supply a walling system – it supplies steel cladding profiles that may be installed on walls. Fielders® cladding has been tested for concentrated loads and pressures as required by relevant Australian Standards, codes and the NCC. Compliance to these standards and codes is documented in relevant Fielders® product design and installation guides and on the Specifying Fielders website.

As a consequence Fielders® are unable to certify its products as meeting NCC Performance Requirement FP1.4 for weatherproofing metal wall claddings for Class 2 – 9 buildings.

It is the responsibility of others to design/detail/test the wall system to provide various features (water resistance via flashing details & sealing, moisture management via flashing and membranes, insulation, etc.).

The designer of the building will need to refer to the NCC with regards as to what may be required for the particular situation.

2. Walling – Residential applications

For residential walling applications the use of Fielders® cladding products is covered by the “deemed-to-satisfy solution” (Acceptable Construction solutions) in NCC Volume 2 Part 3.5.5.

Performance Requirements Section – P2.2.2 Weatherproofing

  • A roof and external wall (including openings around windows and
    doors) must prevent the penetration of water that could cause;

    • unhealthy or dangerous conditions, or loss of amenity for occupants;
    • and undue dampness or deterioration of building elements

Deemed-to-satisfy provisions for the weatherproofing and durability requirements above are outlined at:

  • Part 3.5.1. Sheet Roofing - Part 3.5.1.0 Acceptable Construction Manuals, which outlines that the Performance Requirements of P2.1.1 and P2.2.2 are satisfied if the sheet roofing complies with a combination of;
    • AS 1562.1 for buildings with a design wind pressure not exceeding N3 and for cyclonic regions documented low-high-low pressure testing to table 3.5.1.0
    • Part 3.5.5.0 sets out that the Performance Requirements of P2.1.1 and P2.2.2 are satisfied for metal Wall Cladding if it is designed and constructed in accordance with AS 1562.1
    • Part 3.5.1.2 sets out corrosion protection and compatibility requirements for roofing detailing minimum coating requirements in accordance with AS 1397 Metallic coated steel and AS 1397 Metallic and organic coated steel

In summary, for residential applications, if the Fielders® wall cladding is designed and constructed in accordance with Fielders® relevant published Design and Installation Guidelines, which have been prepared in to comply to AS 1562.1, then it meets the Performance Requirements of the NCC.

3. Roofing – Non-residential and Residential applications

For non-residential and residential roofing applications the use of Fielders® cladding products is covered by the “deemed-to-satisfy solution” provided in NCC BCA Vol 1 (extract below), Part F 1.5 (d) “Roof coverings”.

In summary, for non-residential and residential applications if the Fielders® roofing is designed and constructed in accordance with Fielders® relevant published design and installation guidelines which have been prepared in to comply to AS 1562.1, then it meets the Performance Requirements of the NCC.

NCC BCA Vol 1 - extract

RoofingWalling
ResidentialDeemed-to-satisfy
solution NCC BCA Vol
1, Part F 1.5 (d)Roof
coverings
Deemed-to-satisfy
solution. Acceptable
Construction solutions
NCC Vol.2 part 3.5.5
Non-
Residential
No deemed to satisfy
solution. Requires
complete walling
system certification

Background

The National Construction Code (NCC) is Australia’s primary set of technical design and construction provisions for buildings. As a performance-based Code, it sets the minimum required level for the safety, health, amenity, accessibility and sustain ability of certain buildings.

It primarily applies to the design and construction of new buildings, and plumbing and drainage systems in new and existing buildings. In some cases it may also apply to structures associated with buildings and new building work or new plumbing and drainage work in existing buildings.

The Australian Building Codes Board (ABCB), produces and maintains the NCC. When determining the content of the NCC, the ABCB seeks to:

  • ensure requirements have a rigorously tested rationale; and
  • effectively and proportionally address applicable issues; and
  • create benefits to society that outweigh costs; and
  • consider non-regulatory alternatives; and
  • consider the competitive effects of regulation; and
  • not be unnecessarily restrictive

The three volume NCC 2019 comprises

  • the Building code of Australia, BCA (Volumes 1 & 2)
    • Volume 1 – Class 2 to 9 buildings i.e. Multi-Res, Commercial, Industrial, and public assembly buildings
    • Volume 2 – Class 1 and Class 10a, certain 10b and Class 10c private bushfire shelter, buildings
  • the Plumbing Code of Australia, PCA (Volume 3)

Compliance with the NCC is achieved by complying with:

  1. The governing requirements of the NCC; and
  2. The Performance Requirements

Compliance with NCC - Performance Requirements

Performance Requirements are satisfied by one of the following

  1. A Performance Solution
  2. A Deemed-to-Satisfy Solution
  3. A combination of 1 & 2

A Performance Solution is achieved by demonstration of;

  1. Compliance with all relevant Performance Requirements or demonstrable and documented equivalency to the Deemed-to- Satisfy Provisions
  2. The Performance Solution must be shown to comply through a combination of the nominated assessment methods.

a. Evidence of material suitability as outlined in section A5 of NCC

b. Verification methods accepted by relevant authorities that document compliance with the Performance Standards

c. Expert judgement

d. Comparison with Deemed-to-Satisfy Provisions

     3. The Performance Solution must clearly

a. Identify and document the relevant Performance Requirements

b. Identify and document the Performance Requirements for all interacting elements that maybe affected by the Performance Solution

 

A Deemed-to-Satisfy Solution is deemed to meet the Performance Requirements of the NCC when the solution can show compliance with the Deemed-to-Satisfy provisions via;

a. Documentation / evidence of the products compliance to the Deemed-to-Satisfy provisions

b. Expert Judgement

c. Demonstrated compliance to appropriate acceptable construction methods or manuals contained in BCA Vol 2

Australian Standards referenced


AS 1562.1:2018: Design and installation of metal roof and wall cladding, Part 1: Metal

AS 1397-2011: Continuous hot-dip metallic coated steel sheet and strip—Coatings of zinc and zinc alloyed with aluminium and magnesium