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Guide to substituting products

Are you considering or required to substitute or change a building product for one that was originally specified or requested? This information will help you manage the product substitution process while complying with the regulatory framework and the National Construction Code (NCC).

In this article

  • Substituting a product
  • When should product substitution be considered?
  • Product substitution and COVID-19
  • Different types of product variations
  • Substitution and approvals
  • NCC product documentation requirements
  • Understand the implications of substitution of a product or system
  • Notifying the building certifier/surveyor of product changes
  • Products that are components of building systems
  • Contractual responsibilities and implied warranties
  • Discuss changes with relevant parties
Different types of product variations
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  • Products may be specified by reference to a Standard. If so, any other product meeting or going beyond that Standard from any manufacturer could be used
  • Products may be specified by naming a specific product or manufacturer or showing the option of selecting equivalent products by stating ‘or equivalent’ in the plans or specifications
  • Seeking subsequent approval for alternate products to be used where it may materially change the design, performance or aesthetics of the dwelling.

When thinking about substituting a product in a building project, it’s good practice to follow a process that considers the effects of the change and makes sure that the related parties are aware and, where needed, have approved the change. 

NCC product documentation requirements
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Building legislation requires all parties in the supply chain to make sure that the materials and products used in building work are fit for purpose. Part A5 of the NCC sets out the product documentation requirements for building products (excluding electrical products). These provisions explain how to provide evidence of suitability for ‘a material, product, form of construction or design’ to demonstrate that it is fit for purpose for the application it will be used in. 

Products can comply through a Performance Solution or Deemed-to-Satisfy Solution and may include one or a combination of the following:

  • CodeMark Certificate of Conformity
  • Certificate of Accreditation (state-based accreditation system)
  • Certificate or report issued by a product certification body accredited by JAS-ANZ 
  • Report issued by an Accredited Testing Laboratory
  • Certificate or report from a professional engineer or other appropriately qualified person
  • Another form of documentary evidence.

For more information on those compliance pathways you should refer to the NCC directly, the ABCB evidence of suitability handbook or refer to other information produced by the HIA.

Notifying the building certifier/surveyor of product changes
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As noted above, under most circumstances apart from minor immaterial changes, the building certifier/surveyor will likely need to be informed of the change. The building certifier/surveyor will generally take into consideration the following:

  • Decide whether these variations can be approved or require updates or changes to the approved plans
  • Advise whether the variations can be treated as minor variations or require an amendment to the building approval.

Ideally, you should notify the building certifier/surveyor as early as possible to avoid any unnecessary delays.

If a product is substituted without approval you may encounter a problem when the building certifier/surveyor goes to issue the final certificate as the building work will not match what is on the building permit.

Product substitution and COVID-19
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Coronavirus (COVID-19) may have a global impact on supply chains and business operations and the extent of the impact of the current situation will most likely be unknown for some time. 

Delays in getting building supply can negatively impact your building projects, including finishing times and timeframes for starting new jobs. 

With availability of some products being impacted at present and potentially into the future, there may be a need to consider changing or substituting some products to allow projects to be completed.

Again, this reinforces the need to manage the changing of products carefully and ensure regulatory and contractual requirements are still met. Keeping open lines of communication with relevant parties, particularly the owner and building certifier/surveyor, is equally important.

Products that are components of building systems
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A building system is a combination of products specified by a manufacturer, supplier or designer to be used together, as a system, to achieve the requirements of the NCC.

Extra caution needs to be taken when thinking about substituting a product that is part of a building system. 

This is because the change will most likely affect the performance of the whole system. The proposed substitute product may not have been tested for use with the other components, or the system may fall outside the scope of use defined by the manufacturer.

Changing a component that forms part of a system may also void any warranty offered by the supplier or manufacturer.

Substituting a product
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For many reasons a party to a building project may consider using building products that are different to those originally specified in the building permit or requested as part of a contract.

Substitution can sometimes be simple and easy, such as when switching one brand of product for an equivalent alternative. Other substitutions, however, can be complex, time consuming and risky. 

If not managed correctly product substitution can potentially create legacy issues for the building if a full evaluation of the proposed change is not undertaken.

In certain circumstances, substituted products can compromise the performance of the building as a whole.

With more new products and systems coming into the building industry and many of these being ‘building systems’, performance and certification can be dependent on the specified and ancillary products that must be used in accordance with the product documentation. 

Therefore, managing changing of products to those originally specified or requested requires careful consideration.

Substitution and approvals
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Products included in ‘building work’

Products included in ‘building work’ must comply with the NCC. What is considered ‘building work’ is defined in state and territory legislation. In carrying out building work, a building approval must be obtained from the relevant building certifier/surveyor for the project or the local council in some states.

If the building work is considered ‘exempt work’, this means a building approval is not required but, as it is still building work, it must comply with the NCC.

However, products such as fittings and fixtures (i.e. door handles, paint, skirting and architraves, appliances, etc.) are not regulated under the NCC or as ‘building work’ and these products can be substituted without need for reference to the relevant NCC or building application/approval. They may, however, be covered in contractual requirements or general specifications agreed to with the home owner.

Categories of product substitutions

Product substitutions will generally fall into one of the following categories:

  • Those that can be done as of right as they do not involve building work (e.g. changing skirting or decorative mouldings, or using wallpaper instead of paint)
  • Minor immaterial changes – these would be done as of right under most circumstances, but still need to comply with the NCC
  • Medium variations, which could involve a design change or project change that has material impact, will likely require approval by the building certifier/surveyor and then be recorded on the final approval (these may require updated drawings or new technical information to be given)
  • Substantive variations, which will require a formal change to the building approval and may require changing plans and specifications and subsequent re-approval before they can go ahead.
Understand the implications of substitution of a product or system
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When substituting a material or product it is important to understand the building context.

Certain products may have been specified for a reason, particularly if the product is part of a Performance Solution and a substituted product may significantly change NCC or performance compliance that has been achieved for the project. Points you should think about include the following:

  • Is the property in a high-wind, bushfire, flood or corrosion zone? Is the substituted product appropriate for these?
  • Have certain design choices already been made and will substituting a product reduce compliance or alter any aesthetic building features?
  • Are there any restrictions under heritage or health and safety legislation, planning restrictions or similar regulations?
  • Will the product substitution change a Deemed-to-Satisfy Solution into a Performance Solution?
When should product substitution be considered?
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You may want to consider substituting a product in the following circumstances:

  • The specified product might not be available locally, or may take too long to deliver
  • Different products might be easier to install/assemble, or have better performance
  • The specified product might be available only through a custom manufacturer, making it expensive and having limited availability
  • Contractors may not be familiar with the specified product and charge a higher price for installation or due to unfamiliarity with the product, or concerns may be raised about installation quality or preference of different brand of same product type
  • In the time between project design and project build, specified products may have become unavailable, may be superseded by newer products, etc.

Unfortunately, some people may see ‘product substitution’ as builders seeking to save costs by using an inferior product. However, they often don’t understand that there are often valid reasons for product substitutions.

Contractual responsibilities and implied warranties
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State and territory based building laws set out a number of implied warranties that apply to building work. You cannot contract out of these and non-compliance can have significant consequences. 

Some of these implied warranties include:

  • The building work will be done properly, competently and in accordance with the plans and specifications
  • All the materials used will be suitable and will also be new, unless otherwise stated in the contract
  • The building work will comply with the NCC and relevant building legislation 
  • If the contract states any particular outcome and the owner depends on the skill and judgement of the contractor to achieve it, the building work and the materials will be fit for purpose and of a nature and quality suitable to achieve that result.

Builders should check the contract they have with the owner. If a builder substitutes a product, they may no longer be building what they have been contracted to provide.

Discuss changes with relevant parties
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Product substitution should be discussed with all parties – the designer, builder, project manager and building owner – as all have roles and responsibilities in the process.

Building owners will usually be responsible for making final product decisions for material changes to the design unless they have delegated this responsibility to another person.

Most important, though, is that you discuss any product changes with the building surveyor/certifier for your project as at the end of the day they have to approve the new product.

Most building regulators have information on their websites about what to expect when implementing project variations.


To find out more, contact HIA’s Building Services team.

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