Product Substitution Non-Compliance Risk for Builders

What it is

Product substitution is the most common way a compliant design becomes a non-compliant building.

The specification says one product. It is on a twelve-week lead time, or it came in forty per cent over the allowance, or the supplier sent something else and the trade installed it on Thursday. Someone made a call on site. That call is a substitution, and unless it was authorised and evidenced, it has quietly moved the legal risk for that element from the designer onto the builder.

A substitution is not the same thing as a non-conforming product. A non-conforming product does not do what it claims. A substituted product can be entirely conforming and still leave the building non-compliant, because it was never assessed for the application it has just been put into. Conformity is about the product. Compliance is about the product in this wall, in this building, in this wind zone.

Who can authorise it, and it is usually not you

The builder building to a design does not own the design. If the specification names a product, the designer selected it to satisfy a Performance Requirement of the National Construction Code, and the certifier approved the documents on that basis.

Changing it requires the designer to confirm the replacement satisfies the same requirement, and where the change is material, the approval documents to be amended. A builder who substitutes unilaterally has redesigned part of the building without a licence to do so.

Evidence of suitability is the whole game

NCC Part A5 sets out what counts as documentary evidence that a material, product or form of construction meets a Performance Requirement. A supplier email does not count. A brochure does not count. What counts includes:

• a current CodeMark Australia certificate of conformity
• a current certificate of accreditation
• a current certificate from a certification body stating the product fulfils the specific NCC requirements
• a report from an Accredited Testing Laboratory setting out the tests and the results
• a certificate or report from a professional engineer or other appropriately qualified person
• a Product Technical Statement

Every copy must be unabridged. A one-page extract of a fire test report is not a fire test report.

The standard-specific traps

The Australian Standards called up by the NCC and published by Standards Australia tie the product to a rating, and a substitution breaks the rating without breaking anything you can see.

• Timber, AS 1684. Framing is designed to a stress grade, a species and a wind classification. Swapping MGP10 for a lower grade changes the span tables the frame was designed from. The frame stands up. It is still non-compliant.
• Wind, AS 4055. Windows, doors, roof fixings and tie-downs are rated to a wind classification. A cheaper window rated N2 in a house designed to N3 is a substitution nobody sees until the first real storm.
• Concrete, AS 3600. Changing the mix, the exposure classification, the cover or the mesh grade changes the durability and structural design the engineer signed off on.

What it costs

Combustible cladding is the precedent. Victoria answered it with a 600 million dollar rectification package, half funded by government and half raised over five years through the building permit levy. Those were substitutions, at scale, that nobody checked at the time.

• In NSW, using a building product subject to a use ban under the Building Products (Safety) Act 2017 can attract a fine of up to 1.1 million dollars for a corporation and 220,000 dollars for an individual.
• The certifier will not sign off, so occupancy and the final claim stall.
• Rectification is at your cost, and it is usually destructive.
• A defect caused by a product you substituted without authority can be an excluded claim, because the loss flows from a departure from the approved design rather than workmanship.

The paper trail that protects you

Substitution is legitimate. Undocumented substitution is not. Four documents turn one into the other.

1. The written substitution request. What was specified, what is proposed, why it is proposed and what the equivalence argument is.
2. The designer's written approval. From whoever owns the Performance Requirement, before the product goes in.
3. The evidence of suitability, filed. The CodeMark certificate, the test report or the engineer's certificate, held on the job file rather than on the supplier's website.
4. The as-built and the approval, updated. If the change is material, the approved documents are amended so the certifier signs off on the building that actually exists.

The detection signal

Walk the job with the specification, not the delivery dockets. Anything on site that is not on the spec is a substitution. If the file does not hold a designer's written approval and a piece of Part A5 evidence for it, you are carrying that element yourself.