2021 NCC Seminars: Does C1.5 still apply if I have a basement carpark?

Does C1.5 still apply if I have a basement car park? C1.5 is that provision, two-story class 2, three or 9C buildings in Volume One. It's among those provisions that are the start of part C1, which are about allocating a type of construction to a building, and under table C1.1, a class 2, 3 or 9C building with a rise in stories of two, would normally be of type B construction.

But then you get to C1.5 which brings a concession, that can bring that type of construction back to type C, if you meet certain criteria. For a class 2 or 3 building like this one, this class 2 example here, those criteria are that each sole occ unit has access to either its own direct access to road or open space, like the ground floor units here, or access to at least two exits like these upper floor units, where you can get to the exit stair at the far end or the close exit stair that you can see here.

So under that concession, C1.5, this building can be a type C building. But What if I had a basement car park? The rise in stories would still be two, but would it still be type C? Let's have a look. Here's the provision that we're talking about. C1.5. And we're talking about a class 2 or 3 building. So straightaway we can ignore for now.

Though I will come back to that in a little while. The first thing to note is that the provision refers to a building that is class 2 or 3. It's not mentioning a class 7A carpark or any other classification. So on that basis, many would say that the answer is no, you can't have a basement car park. But someone might say what about A1.0 ?

A reference to a building is in reference to an entire building, or a part of the building as the case requires. A1.0 is a rule for interpretation found at the beginning of the NCC and the governing requirements, and it says a reference to a building is a reference to an entire building or a part of the building as the case requires.

What does that mean? Well, it means when you pick up the NCC and see the word building, that might be everything - the entire building from footings through to roof, or it might only be a part of the building. Now this might seem confusing, but I suggest to you that you do this all the time. Let me show you. Think of the scenario that we're working through right now. We have a class 2 building of two stories. That's above the ground, rise of stories of two.

We have a class 7A basement car park. Let's leave section C for a while, and we'll go to section E services and equipment. Now E1.4 is about providing fire hose reels to a building. And if the basement is greater than 500 square metres, then it's going to need fire hose reels. Yes? However, E1.4 has this concession. It says E1.4 does not apply to a class 2 building. So does that mean the car park doesn't need fire hose reels?

Because this whole thing here is a building from foundation to roof. It's a building. It's a class 2 one predominantly. So does this concession in E1.4 , which applies to a building, mean that we don't have to provide fire hose reels to the basement?

Of course not because of A1.0 , a reference to a building is a reference to the entire building, or a part of the building as the case requires. And in this case, the concession found in E1.4 , that word building is referring to the class 2 part only. Therefore the basement, if more than 500 square metres, would need to have fire hose reels. That's how A1.0 works.

But I'm going to show you how, in this case for C1.5, that word building means that the whole thing has to be class 2 or 3. The entire building from foundations to roof. It goes like this, the word building, applied to a class 2 building, appears twice. Once in the leading and again in subclause.

Now if we want this example on the left, with the basement car park, to be a type C building, then we need that first word building in the leading to be the entire building, carpark included, because that's what can be type C.

It says so in the lead in that building having a rising stories of two maybe of type C construction. We need that word building to apply to everything. If we want the example on the left to be a type C building, then we also need that second occurrence in subclause A of the word building.

That has to apply only to the class 2 part not the entire building, because the criteria for the concession is that the building has to be class 2 or 3. And the car park is neither. Now. That first word building and the second word building are the same thing because of the word 'it'.

The building is type C if it is class 2, or class 3 for that matter. And so the whole building on the right is a type C building. It's class 2, it meets the criteria, but the whole building on the left, foundation to roof, doesn't meet all the criteria for the concession and therefore needs to be a type B building.

Because it's not all class 2 or 3, the 7A part doesn't meet that criteria. And when you think about it, the building on the left is more complex than the one on the right. So it's appropriate for the concession to not apply.

However, of course, this can inform a performance solution to address the implications of type B construction. I said before that I'd come back to subclause B and notice that it's written the same way. The word 'it' makes the word building from the lead in, with the word building in the subclause. So it's the same thing and needs to be entirely class 9C, sprinkler protected. And so on.

So does C1.5 still apply for have a basement car park? The answer is no. It may provide a good precedence for dealing with the implications of type B construction for a performance solution, but it's not a deemed to satisfy concession.