What setback do I need for the open carport concession?

Video

The 2017 NCC Information Seminars included a presentation on ‘What setback do I need for the open carport concession?’ as part 3 of the 13 part BCA sessions delivered throughout February and March 2017.

Transcript

We're just getting through this one easily. I'll quickly get into the next one which is what setback do I need for the open carport concession? This is a recent inquiry. I see some laughter already. Fantastic. Laugh at my jokes please because we're on video today.

What setback do I need to the open carport concession? An inquirer wanted some clarification over 3.7.1.6 in Volume 2, specifically about the open carport concession. 3.7.1.6 contains requirements which inhibits spread of fire from one Class 1 building to the other. We don't care about the Class 10. They can burn, that's fine. We're just stopping the fire spread from one Class 1 to the other, and that is directly from performance requirement P2.3.1 So the Class 10a building, the Class 1 is of course, the house or the boarding house. And the Class 10a, it could be the shed, it could be a deck, it could be the carport.

And that's why we have provisions, Deemed-to-Satisfy provisions in 3.7.1. And these referred to two tables such as 3.7.1.6, Figure 3.7.1.6, where we achieve this performance requirement by stopping the fire getting from one Class 1 to another by having physical separation between the two as in the top example there. Or installing walls which have an FRL which prevent the fire spread from getting from one Class 1 to the other via the 10a.

When we use separation, the required setback is either 900 millimetres from a boundary, or 1.8 metres from another building when that's on the same allotment. So of course, the 900 from the boundary. I do that on my side, and then my neighbour does the 900 on his side. We get the full 1.8. That's how we how we do it, and this is all in accordance with 3.7.1. 4: Measurement of distances, which is found right at the front of 3.7.1. And it sets out how distances in this part of the code are measured. And all these distances, note, are taken from the external wall of the building, from the external wall of the building to the boundary or the next building. So, for these Class 10as in this diagram here, the measurement is taken from the wall. Let's call them garages.

The measurement is taken from the wall of the garage. Not the eaves, not the gutter but taken from the wall in accordance with 3.7.1.4. Right here at the start of 3.7.1 Now carports. they present a lower fire hazard than garages and other Class 10a buildings. So, we get this concession in 3.7.1.6 and you may have heard this called the open carport concession. Under this concession, you have to have at least two sides open and at least one-third of the perimeter as open. That is the most boring ringtone that I've heard … you could have a song, you could have all sorts of things. I've got a lovely song when my wife rings me. Just ring, ring, ring. Look it up. Sorry.

We have to have at least two sides open and at least one-third of the perimeter open. And to be open, you can't have a wall. And also, there's some things about the roof covering. The roof covering, besides what it's made out, of has to be at least 500 millimetres from another building or the allotment boundary. This is all in accordance with 3.7.1.6D. Now this 500 millimetres, what it does, it gives a chance for smoke and heat to escape through the roof. So that you've got one Class 1 and another Class 1. You come to the 10. You got this 500 millimetres. The smoke and heat escapes rather than getting condensed and then causing the adjacent Class 1 to catch alight. So, let's say… is this why you laughed before, Sir? Just how badly drawn it is. Okay, well I'm glad you've come today. Thank you for coming.

This carport is open on two sides. The far side’s the wall is probably the house so that's not open. The front has the garage door so it's not open. However, the rear is open. There's nothing constructed there. And the side here, as long as we're 900 millimetres away… I'm sorry, allow 500 millimetres for the open carport concession, if it is an open carport. But, yes it is, because we're we also meet the third rule. This side, so long as the boundary is far away, or an adjacent building is far away, it's also open. Now note how these are measured. This is all in accordance with 3.7.1.6D. Unlike those measurements that we’re used to using, you go all through Figure 3.7.1.6 and you use the rule set out in 3.7.1.4, where you measure from the external wall.

This diagram shows us how it's done. It’s straight from Volume 2. It’s measured from the roof covering to the closest part of the adjacent building. So, for the Class 1 to the house, it's actually measured from the gutter in this case, not the wall, because we're not applying 3.7.1.4. we're applying 3.7.1.6D which sets out that it's the 500 millimetres distance from the closest part of the adjacent building or from the boundary of course, on the right.

Another important thing to note when applying the open carport concession is it doesn't double up. We're used to my house, neighbor's house. I've got my 900, he's got his 900. We've got our 1.8. And when you put the buildings on the same allotment, we double up and get that 1.8. The open carport concession doesn't double up. Let's call them garages on the left-hand side there. We've got our 1.8 meters wall-to-wall in accordance with 3.7.1.4: the measurement of distance. On the right, we have two open carports. The 500 millimetres doesn't double up. When I consider this carport, I simply have to have the closest part of the roof, or closest part of the adjacent building not less than 500 millimetres away. Tick. When I consider this carport, I have to be sure that the adjacent one is not less than 500 millimetres away, all in accordance with 3.7.1.6D. Tick. So that 500 millimetres doesn't double up. Important to note. And it all comes down to getting your head out of the 3.7.1.4 and applying the way of applying in 3.7.1.6.

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