NCC 2025 webinar series: Governing requirements

Thanks, Adrian. Hi, I'm Graeme, principal building surveyor at the ABCB and director for NCC management and standards. I'll begin today's session by showing you changes in the governing requirements. Starting with a change in A2G2 relating to expert judgment. Ever since the BCA became a performance-based code in 1996, the NCC has specified four assessment methods for verifying that a performance solution complies with the relevant performance requirements. These are described in A2G2 and are firstly evidence of suitability. For example, you might have a codemark certificate that attests compliance with a performance requirement. That's a performance solution. So, it's listed here in A2G2. Secondly, verification method. This is a way of verifying compliance. There's verification methods outlined in the NCC, but you don't have to use just those. A performance solution can use verification methods not contained in the NCC. Also, third is expert judgment. This is a defined term which is paraphrased on this slide. This one is useful for subjective performance requirements. For instance, many performance solutions concerning access for people with a disability will incorporate expert judgment. Fourth is comparison with deemed to satisfy provisions. This is a common one because it's a great way of showing compliance. If the performance solution is shown to be as good as, if not better than the DTS solution, then it's a good solution. It was identified that for structural safety performance solutions and fire safety performance solutions, expert judgment isn't appropriate. These sorts of performance solutions can be verified quantitatively. So for NCC 2025, expert judgment is removed for structural and fire safety performance solutions. You can still use expert judgment for other performance solutions. This is the list of affected performance requirements. Note that part G5 and H7 P5 aren't listed here. This doesn't apply to bushfire. Part H3 isn't listed here either. So volume 2 fire safety isn't affected. For fire safety, only the requirements of parts C, D, and E in volume 1 are listed. and the structural reliability requirements of B1P1 sub clause 2 in volume 1 and H1 P1 sub clause 2 in volume two. I'll mention in passing now another change which will be covered in more detail in a few slides time. That change is that besides not using expert judgment, performance solutions about structural reliability must use the verification method in the NCC and also be shown to be at least equivalent to a deemed to satisfy solution. More on that later, but now I'll describe a new initiative regarding NCC reference documents. Most of you will be familiar with how the NCC references other documents such as Australian standards for test methods, for technical specifications, and for design like here in H1D4. Now, this new initiative is about which addition of a standard is to be used. I'll get to the change in a moment, but first I need to explain how it's currently done. Currently, every time you see a document referenced in the pages of the NCC, to know which addition to use, you turn to schedule two. In this case, schedule 2 informs us that the 2011 edition of AS2870 residential slabs and footings is the referenced edition. And quite often that primary reference document will refer to other reference documents. When this happens, it's called a secondary reference document. If that secondary reference document is also referenced directly by the NCC and so is in schedule 2, then you use the addition referenced by the NCC. But if it's not referenced directly by the NCC, then you use the addition that existed when the primary reference document was created. There's a reason for this which makes it easy to understand and that is when the committee writing a standard is calling up another standard they are thinking of what that secondary reference says at the time. They don't have a crystal ball to know what it's going to say in the future. So the default is that the secondary reference is the one that existed when the primary reference document was published. However, it doesn't make sense for the NCC to use two different additions of the same standard in the same project. So for that reason, if the secondary reference document is also a primary reference document, then the addition that's caught up in schedule 2 is the addition that you use. For example, AS 3600 concrete structures is referenced by AS2870. It's also a primary reference document in the NCC. So you use the addition called up in the NCC, the 2018 edition for the purposes of AS2870. Even though this addition didn't exist when AS2870 was written, AS-2870 also references AS- 4671 for specifying the steel used in concrete reinforcing. There's a 2019 edition of that standard available, but the edition that's referenced for the NCC is the 2001 edition because AS4671 is not a primary reference document. So you use the addition that existed when the primary reference document was published. That's how reference documents currently work. And this gives background to the problem that alternative reference documents addresses. This problem has always been around but was most apparent when we moved to a three-year cycle in 2016. So I use the example of AS NZS 4600. NCC 2016 caught up the 2005 edition of that standard. But in 2018, a new addition was issued. That addition had some improvements, so people were keen to use it. However, it wasn't caught up until NCC 2019, which left this period where the new edition was available, but the old edition was the one referenced by the NCC. Now, this has always been the case that there's a delay between a standard edition being published and it being caught up in the NCC. But you can see how it became more of a thing with a three-year amendment cycle. Under an annual cycle, you usually just had to wait until the following year. But under a three-year cycle, this delay could actually be longer than 3 years because we start preparing the next edition well before we intend to publish it. We had an odd solution for this. On our website, we had a table of reference documents that had been approved for the next edition of the NCC. As our technical committees approved new additions, including the 2018 edition of AS-4600, we'd put them on the website. This was useful information for people preparing performance solutions to use the new edition. However, the problem with the old solution is that the trouble and expense of putting together a performance solution sometimes outweighs the benefit of using the new addition. Which is why we've introduced this new initiative of alternative reference documents. As the title indicates, instead of using schedule 2, you can use a register that will be on our website. That register is an option to schedule 2. And as new additions get published and ratified, they'll be included on the register. So, for example, if there's a 2027 edition of AS2870, it could potentially be included in the register and therefore used for NCC 2025. When it comes to the secondary reference documents, similar to how it is now, you'll use the addition in schedule 2, unless the register gives other directions about secondary reference documents. If the secondary reference isn't in schedule 2, and if the register doesn't give instructions, then the addition you use is the addition that existed at the time of publication. So that 2019 edition of AS4671 steel for concrete referenced by AS2870 would be called up if there is a 2027 edition of AS2870 included on our register. There's a few things to keep in mind. Firstly, under a DTS solution or a verification method in the NCC, you have to use only one edition. You can't pick and choose from each edition unless you demonstrate that this is okay using a performance solution. The reason for this is that all the different rules of a standard work together as a whole. Changing one provision nearly always has an effect on other provisions. So when a committee develops an addition of a standard, they contemplate these inter relationships and amend other provisions if necessary. So you can't come along and pick and choose provisions that work with you without also doing the work of demonstrating those inter relationships aren't affected. Secondly, when it comes to state territory variations, the alternative reference documents register does not apply unless the register itself says that it does apply. And also that register will be available on our website abcb.gov.au when we have the first approved alternative reference document. More information in A4G1, so be sure to look at that provision in NCC 2025. This new initiative means that it could potentially become hard to know which edition of a reference document was applied to a given project. At the moment, it's not too hard. You go to the applicable NCC edition to see what version of a standard was referenced. But under alternative reference documents, that could be the addition in the NCC or the addition in the register. And to make things more complex, it's entirely feasible that the addition in the register could be updated before the NCC edition changes. So, we must all be good citizens and clearly document which addition of a standard was used for a given project. We've put in an explanatory information box to remind you all to be good citizens and leave a good paper trail for when buildings we certify today are altered in the future. Some changes have been made to A5G6. First, in NCC 2022, this clause was only about fire hazard properties for NCC 2025. It also includes combustibility because this section of part A5 has always described how to determine FRLs, fire hazard properties, resistance to incipient spread of fire but not combustibility. So that's included this year. But to introduce the big change in A5G6 for this year, I ask you this question for fire hazard properties. Is it okay to accept an assessment report based on a similar prototype or does each and every prototype require its own test report? Some of you are thinking yes, an assessment report is fine. Some are probably thinking no, you need to get a test report. And I suspect some of you are thinking what's an assessment report? If you're in that last category, this next slide's for you. Assessment report isn't defined in the NCC. In fact, you won't find the words assessment report anywhere in the NCC. So, you're forgiven for not knowing what it is. Most test labs in Australia call it an assessment report or a product assessment report when they certify the performance of a prototype without actually testing the prototype. You might have also heard of this as an extended application report. This might seem dodgy, but there's many circumstances where this would be okay. For example, it's very common for penetration protection systems to have FLL assessment reports. If this fire collar is tested and works fine in core field concrete blocks, then it's going to work in concrete walls of the same width. So rather than run another test to find out what everyone knows, the lab can write an assessment report saying that the collar is good for concrete walls. Also, this is sound practice and is permitted by the NCC in C4 D15 sub clause 2A1B which allows departures from the tested system described in AS 4072.1. So, our assessment reports okay for fire hazard properties. In one sense, yes, it's sound practice. I might have a wall panel that comes in a range of thicknesses. If my thinnest panel and thickest panel comply, then there's no doubt that all the thicknesses in between comply. Therefore, I only need to submit my thickest and thinnest panels for test and the rest can be certified by assessment. However, the NCC doesn't currently have a provision like C4 D15 sub clause 2A1B for group numbers or any other fire hazard property. So, that's changed in NCC 2025. As mentioned, done properly, it's legitimate practice. So, we've included this sub clause in A5G6 to allow it. Also, for the first time, we're permitting assessment reports for combustibility. This is useful for materials like insulation where there are differing levels of binding agent. So, the material with the least binding agent is tested and so is the material with the most binding agent and all the materials in between are certified by assessment. This next change is in both volume one and volume two. It's to do with performance solutions for assessing structural reliability, which is what B1 P1 subclaus 2 is about in volume 1 and H1P1 subclause 2 is about in volume 2. It also involves a new verification method for structural reliability that replaces the existing verification method known as B1 V1 in volume one and H1 V1 in volume 2. I've listed the relevant governing requirement here also A2G2 subclause 5. I'll show you that in a moment. But before I do, I'll revisit verification methods. You'll remember in my first slide I said that expert judgment was removed for structural and fire safety performance solutions. That's still the case except when it comes to structural reliability performance solutions. NCC 2025 introduces a requirement where you have to use the verification method and in addition in most circumstances you will have to compare the outcome of your performance solution with the outcome of the deemed to satisfy provisions. In other words besides the verification method you also have to do comparison with the deemed to satisfy provisions. That's because of this new sub clause 5 in A2G2. When you're doing a performance solution for specific materials, then you have to demonstrate that the solution is at least equivalent to the deemed to satisfy provisions. The materials are the same for each volume and they are masonry, concrete, steel, composite steel and concrete, aluminium, and timber. Note that this change, the requirement to do comparison we've deemed to satisfy comes with a one-year transition period. I mentioned earlier that using the verification method is mandatory. That's due to this new sub clause that's in both B1P1 for volume 1 and H1P1 for volume 2. Each component of the building or structure must withstand all actions with the minimum levels of reliability specified in the tables listed. They're all new for NCC 2025. in accordance with B1V1 which is a rewrite of the old structural reliability verification method. This webinar isn't the place to go into detail so we won't step through the formula. I'll just use this slide to point out that the minimum reliability indices in the performance requirement for dead loads, live loads and stability loads, think wind uplift are verified using the formula in the verification method. And like the new requirement to do comparison we've deemed to satisfy this requirement to use this new verification method comes with a one-year transition. Before we leave structure, I'll outline changes we've made to provisions regarding wind actions. AS 4055 was updated in light of recent climate data and as a result we've updated the NCC to align with 4055. The biggest change is splitting wind region B into B1 and B2. B1 remains non-cyclonic, but B2 becomes cyclonic. And there have been some boundary realignments. B1 has moved further inland between Bundberg and Coffs Harour. And over in Western Australia, that stronger region that starts at the Tropic of Capricorn has extended north. It used to end at 20° south, but now ends at 19° south. So 80 mile beach is now in region D. Previously it was in region C. Relevant probabilities of exceedence have been updated also. So be sure to check these in NCC 2025 if you work with wind loads. Those are the main changes to the governing requirements and structure. If you have any questions, please stay for the Q&A session.