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Group 1 vs Non-Combustible Building Materials – What is the Difference?

Have you ever wondered what the difference is between non-combustible or Group Rated building materials? Or perhaps you are unsure what test certificate is required?

The recent amendment to the NCC 2016 BCA Vol1 Amendment 1 in March 2018, has also created additional confusions as to what the difference is between the two definitions and also what options you have when choosing a product.

The following definitions of these two words have been defined by the BCA:

non-combustible means:

  • Applied to a material – not deemed combustible as determined by AS 1530.1 – Combustibility Tests for Materials; and
  • Applied to construction or part of a building – constructed wholly of materials that are not deemed to be combustible.

Group 1 Rating means:

A Group 1 material is one that does not reach flashover when exposed to 100 kW for 600 seconds followed by exposure to 300 kW for 600 seconds (as determine by AS 5637)

In very basic terms these products have been tested to determine how long the product will hold back the fire from spreading. The test required for internal walls and linings is AS 5637 and the test for external is ADS 1530.1

BCA Deemed to Satisfy provision & Non-Combustible Materials

The BCA has however also recognised in Deemed-to-Satisfy Provisions C1.9 that there are some materials that can be used wherever a non-combustible material is required

These include:

(a)        Plasterboard.
(b)         Perforated gypsum lath with a normal paper finish.
(c)          Fibrous-plaster sheet.
(d)         Fibre-reinforced cement sheeting.
(e)         Pre-finished metal sheeting having a combustible surface finish not exceeding 1 mm thickness and where the Spread-of-Flame Index of the product is not greater than 0.
(f)          Bonded laminated materials where—(i) each laminate is non-combustible; and (ii) each adhesive layer does not exceed 1 mm in thickness; and (iii)  the total thickness of the adhesive layers does not exceed 2 mm; and (iv) the Spread-of-Flame Index and the Smoke-Developed Index of the laminated material as a whole does not exceed 0 and 3 respectively.

This means that the above materials are suitable to use (without having to undertake additional fire testing) wherever non-combustible products are required.

As these products are also considered non-combustible, products made from the above material are also suitable to use as an internal wall and ceiling lining wherever a Group 1 rating is required.

Be aware of imported products

Given that the above building materials do not require additional fire testing, it is important that you take additional care when considering cheaper, imported products that may state they are made from these materials.

It is therefore critical that you ensure that you request to see documentation that demonstrates that the products have been manufactured to comply with that the equivalent AS/NZ standard.

For example, our new range of through colour fibre cement, Cembrit Patina & Cembrit Solid, is classified as a Non-Combustible product as it is made from Fibre-reinforced cement sheeting (fibre cement). Cembrit is one of Europe’s leading manufactures of Fibre Cement and has documentation to demonstrate that their products are made the correct standards and are genuine fibre-cement flat sheets.

Atkar Group have numerous group rated and non-combustible solutions in our range. You can also use our wall & ceiling lining materials Group Rating Calculator to find out what Group Rating you need for your project. Click on the links below to see more:

It can be difficult to understand all the details of fire compliance, so if you have any questions or want more information, then please contact our Architectural Team on 03 9796 3333 or


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