NCC 2025 webinar series: Fire resistance

Thanks, Adrian. Sometimes a test is necessary to figure out if a material, product, or form of construction complies with the NCC. Sometimes all you need is a tape measure. For example, you might be assessing a doorway into a fire isolated exit. You can use a tape measure to figure out if the width of the doorway complies with D2D9. But your tape measure isn't going to tell you if the door is a dash 6035 door. Of course, you look at the tags on the door and frame. But those tags are there because a prototype of that door has passed the AS 1530 part 4 standard fire test. There's a lot of things in the NCC where compliance is discovered by test. But some of those things are so important that the NCC requires that the test be undertaken by an accredited testing laboratory. This table shows those things. And you'll see that a lot of those things are to do with fire performance, including the standard fire test to verify the FRL of the fire door. For NCC 2025, this list grows with some sensible additions. We've added all the fire hazard properties, group number, spread of flame index, flammability index, all of them. We've also added the external wall performance test of AS 5113 referenced in the fire spread via external walls verification method. And we've also added combustibility, the AS 1530 part 1 test. I'm sure you'll agree that these tests are as important as the ones listed on the previous slide. Note also, a transition period has been provided for this one. You'll see this note next to each relevant provision saying that the requirement doesn't come into effect until the next edition of the NCC. This is to give manufacturers and accredited test labs a chance to test products and materials that need to be retested for this new requirement. We did some research and struggled to find any products that weren't already using accredited labs, but provided the transition period anyway. This next one is a small but important change. This is in C3 D13 subclause two, which sets out a series of concessions from having to fire separate equipment. For a long time, subclause B has exempted stair pressurizing equipment. Fair enough, but the fire isolated passageway connected to it is pressurized, too. Does this mean that the concession doesn't apply when you're pressurizing a passage? Of course it shouldn't, so we've made this clarification in 2025. This next one is also a clarification because the way C4 D3 is worded today, it's not clear how much of a wall would need to be protected if only part of the wall was close to a fire source feature. Because the phrase external wall could mean all sorts of things. Does it mean just the part which is close enough to the fire source feature to require an FRL? So only window A would need protection? Or does it mean the external wall for that side of the building, so that B would also need protection? Or does it mean the entire wall around the whole building? Well, of course, C4 D3 is only intending to apply to opening A. So we've clarified that by including reference to part of an external wall that is required to have an FRL. This next change is another sensible addition. It's to do with C4 D10, which is the provision that says you can't put service penetrations in fire isolated exits, except for a few necessary penetrations, like the wiring for the lights. For NCC 2025, we've added subclause D here because the exit pressurization system needs to penetrate the fire isolated exit, also. We're up to specification five now, which is about fire resisting construction. And if you go back to NCC 2015 and earlier editions, when specification five was known as spec C1.1, it was the case that most load-bearing walls for type A and type B buildings had to be built of concrete or masonry. This sort of rule had good basis. King Charles II made a similar rule around 360 years ago following the Great Fire of London. But, they didn't have fire-rated plasterboard back then. We do now, so arrangements for fire protected timber were first introduced in NCC 2016. Now, with NCC 2025, we have provisions for fire protected steel framing also. As you can see, it's the same, but different. There are many similarities between steel and timber, even down to the protection system specified in the defined term. But, note carefully that while fire protected timber is for classes two to nine, fire protected steel is for class two or three, unless it's confined to the uppermost story. Recently, we had a project known as the modern vehicles project, where we looked into car park fire safety provisions of the NCC, and asked ourselves, are these provisions fit for purpose for modern vehicles? These are the provisions that have been amended by that project with the descriptions found in the list of amendments. We're not going to look at these one by one today. You can note these down and do that another time if that's your thing. Rather, I want to summarize these changes like this. What those changes achieve. The first column lists car park types and features being compared. The middle column describes status quo in NCC 2022. And the final column shows NCC 2025. The highlighted cells show where something's new for NCC 2025. As you can see, the changes involve sprinkled open deck car parks, sprinklers wherever there is a car stacker, and less fire resistance level concessions. So, more active fire suppression and more passive fire resistance. And the reason we got here is that we don't see cars like these anymore. A 1982 XE Falcon. Now, unless you're a nostalgic Ford fan, you'd say that this is a good thing that we don't see cars like this anymore. But the reason I show you this photo is that this model Ford was one of the car types used in the full-scale fire testing that led to the car park fire safety provisions in today's NCC. A series of tests were done in the mid-1980s by BHP, where they built a mock-up of a steel frame car park, put some cars in it, and set a 1979 XC Falcon on fire. In the first test, only the test car burnt, even though the car right next to it had its window down. In the second test, the burnt car was a 1982 XC Falcon like the one I showed you a couple of slides ago. This time, the car with its window down caught a light at 15 minutes into the test, and the car on the other side caught on fire at about 35 minutes into the test. But that's all. They stopped the test at 70 minutes with only three cars catching on fire. This presentation isn't the place to go into detail about all those tests. If you'd like to know more, I recommend a literature review on our website, abcb.gov.au, which describes these tests. Search for fire safety in car parks ABCB literature review. For today's presentation, note that these tests showed that vehicle-to-vehicle fire spread was minor and that steel could withstand the peak temperatures. So, today's NCC allows unprotected steel open-deck car parks besides sprinkler and FRL concessions. But, modern cars are different to the Falcons burned in these tests. They're bigger, heavier, covered in plastics, have a much higher calorific potential, and electric vehicles are presenting new fire behaviors that need consideration. And vehicle-to-vehicle fire spread happens quickly. This photo was taken during demolition of the Echo Arena car park in King Street, Liverpool. It was an open-deck car park which complied with the UK's building codes. Like in Australia, this car park did not require sprinkler protection. Do you remember that test I mentioned earlier where after 70 minutes they could only get three cars to catch on fire? In this fire, the first fire crew entered the fire-affected story 30 minutes after the fire had started and so many cars were on fire they could not count them. In the end, about 1,150 cars were destroyed. Our modern vehicles work surveyed a number of car park fires. Details of some are shown here. That work showed that vehicle-to-vehicle fire spread is a thing. It also reinforced existing research showing that sprinkler suppression is effective. Hence the changes I outlined earlier where some FRL concessions have been removed and where there's more instances where you need sprinkler protection. Except it's still the case that an open-deck car park that is a separate building does not require sprinkler protection even where there's more than 40 vehicles. This is because our research showed that car park occupancy rates are low, so risk to occupants is also low, unless other classifications are in the building and fire can affect those occupants. This next change is in clause nine of specification five. It's not related to the modern vehicles work I covered just now in this presentation, except that work concluded it was fine for this concession to remain. It's the car park concession in spec five that allows you to use FRLs as for class two or three buildings for the car park level. Just to refresh your memory, so long as all the parameters are met, as is the case for the example shown here, where you'd normally have to choose 120-minute FRLs from the class 7a column, you can choose instead 90-minute FRLs from the class two column. This makes for a simpler build and is a legitimate concession. This isn't new. The outcome hasn't changed, just the words, and here's why. The NCC is very specific about parts of a building being classified according to their use. We even have A6 G1 sub clause two that says each part of a building must be classified according to its purpose. But here in NCC 2022, the NCC is not strictly following its own rules, because it's describing a situation where a class two building is also at the same time a class seven building. You can see this occurs in both sub clauses one and two. Now, you and I both know what they're trying to say. They're talking about a building that is generally class two or class three, and we've been reading it that way for years. Though the NCC should obey its own rules, so we've rephrased this clause. I've only room to show you sub clause one. There's also sub clause two changed for class three and seven buildings. As you can see, it's a total rewrite, but now it's accurate in how it assigns classifications to the different parts of the building. This next one is similar to the previous one. We haven't changed the technical outcome, only clarified what that outcome is. Here's S5C20 subclause two from NCC 2022. S5C23 subclause two is the same concession, only for type A construction. It's the concession that allows timber framing for class two and three buildings, even where there's an ancillary story below, subject to certain parameters. And one of those parameters is that the bottom story, say car park, is constructed of concrete or masonry. And that's fine. I can make the slabs and columns out of concrete. But what about the non-load bearing walls? What about the balustrades? What do they mean when they say the story has to be made out of concrete or masonry? Does everything down there need to be made out of concrete or masonry? Where can you get concrete light bulbs? This one needed clarifying, so we checked the history and confirmed that it's only the load-bearing elements that have to be made out of concrete or masonry. No need for brick balustrades or concrete doors. This one has been updated in NCC 2025 for S5C20 and S5C23. Specification 11, smoke proof walls in health care and residential care buildings. This one's being clarified this year. For a long time, S11C3 has had this concession saying the wall may be lined on one side only. Does that mean that smoke proof walls for class 9A buildings in clause two need to be lined on both sides? In NCC 2025, we've clarified this with a new subclause confirming that yes, this is the case. Also, clause three has specified the plasterboard as being at least 13 mm standard grade plasterboard, but clause 2 has been silent. For NCC 2025, we've clarified that class 9a healthcare buildings need at least 13 mm standard plasterboard also. Both these clauses require smoke dampers for air handling ducts that cross smoke proof walls, but they never have specified what they need to comply with. I'm sure you've all been installing them in accordance with AS 1668 part 1, but we've included that as a clarification also. One last change in specification 11, you're likely familiar with the concession from having to provide a smoke reservoir if the fire compartment is pressurized. Our technical committee considered that a reservoir was justified even where there is pressurization, so the concession has been removed for NCC 2025. Those are the main changes to the fire resistance provisions. If you have any questions, please stay for the question and answer session.