2022 NCC Seminars: Volume Two - Fire Safety

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[Music]

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My name is Phil Finnimore from the Australian Building Codes Board

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and today I'm going to talk about some changes in NCC 2022 relative to fire safety.

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Now the changes being made here haven't fallen from any review of an acceptable construction practice

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but rather a discovery of some provisions currently existing  

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in 2019 that need to be corrected. So what we're  talking about is separating walls between two  

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buildings, that's two Class 1 buildings  and in particular the extension of that  

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fire separating wall as an external wall being  the vertical projection of the building below.

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So in this particular photo we're  looking at a set of town houses.

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The building on the left shaded in yellow is separated from the building on the right  

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through a fire separating wall but you'll  note that there's an extension of vertical  

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projection of that building up to that red  overhanging eave. The problem that we're trying  

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to solve and this is the fact that there's a  potential source of fire spread from the roof  

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in the yellow shaded building into the building  on the right there through that red eave area.

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Now the problem that we've discovered and are  correcting relates to the current provision of  

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3.7.2.7 allowable encroachments where it says  an encroachment is any construction between the  

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external wall of a building and another building  or another boundary or a vertical projection.

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Because the wall, because it's saying an  encroachment is something that is between  

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the wall of the building and something else, it doesn't take into consideration where the  

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projection is beyond that particular line. So the  boundary or vertical projection, that dotted line  

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in the diagram down below, is not caught  by this particular provision because it's  

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extending beyond that it's not captured because  it's not between the wall and something else.

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Which effectively means you can actually  have this particular situation which is not

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a desirable situation to have and doesn't  necessarily meet the intention of the code.

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So what we've done to correct that is added in  the Housing Provisions for 2022 a new subclause  

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in 9.2.9 and that's there in (d), highlighted by  that yellow or red outline, and what it's saying  

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now is an encroachment is any construction that  extends beyond the vertical projection of another  

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building on the same allotment. What that now  means is you can't have an allowable and we can't  

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have an encroachment that extends beyond that  because it is a potential source of fire spread.

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In 9.2.9 there's another section that we've tidied  up as well and if we have a look at this one  

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subclause (1)(c) and encroachment is any construction  between the external wall of the building and  

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the vertical projection of the external wall of  another building on the same allotment. Now that's  

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the outcome we're looking for but if we have  a look at this particular photo and go back to  

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subclause (e) and those same provisions in 2019  you'll see that this particular overhang is not  

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permitted and it's not permitted because in (e)  it's saying the encroachments allowed between  

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the external wall of a building and the vertical  projection of an adjoining building, which is that  

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red dotted line up the middle, is limited to  non-combustible fascias, gutters and down pipes  

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but this situation with that eave overhang is  much safer than one that we showed before where  

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the red overhang overhanging eave was above  that townhouse that was shaded in yellow.

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So the code is saying you can't do this but it's  significantly safer than what we've currently got  

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so what we've done is changed in the Housing  Provisions for 2022 subclause (5) in the allowable  

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encroachment provisions to say encroachments  allowed to project beyond the vertical projection  

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of another building are non-combustible fascias, gutters and downpipes. So you can have an eave  

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overhang in this particular situation, you're  still subject to the limitations of how close  

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that can go to the vertical projection but if  there are any encroachments hanging over that  

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particular red dotted line they can only be  non-combustible fascias, gutters and downpipes.