2022 NCC Seminars: Volume Two - Structure

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[Music]

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My name is Phil Finnimore, I'm one of the Directors in the NCC Management and Standards Team

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in the Australian Building Codes Board. Today I'm going to be taking you  through the changes to NCC 2022 Volume Two and  

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the Housing Provisions and the main aim of this is  to talk about the connection between Volume Two and  

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the Housing Provisions and where all of the Deemed-to-Satisfy provisions from 2019 have been moved  

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into those Housing Provisions and to do that I'll  use the examples from the acceptable construction  

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practice review and go through both structure  and the technical changes for the benefit of  

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the users in the industry. Starting with Part  H1 structure, we'll be looking at footings and slabs

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but before I start and talk about footing  and slabs it's important to note that 2019, you  

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would understand that we have an acceptable  construction practice, that's the black text

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in the Volume Two part of the code and then there  are the acceptable construction manuals which  

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generally are reference documents what we've  done for NCC 22 is separate those out and put  

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Volume Two Deemed-to-Satisfy provisions relating  to the reference manuals, the Australian Standards  

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and then limitations and then reference across  to the Housing Provisions where the acceptable  

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construction practices or ACPs have gone. Starting  with footings and slabs it was one of the first  

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ACPs to be reviewed by an ACP review group that  worked for the Building Codes Committee, what I'll  

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do on this these slides is set out the changes  to the footing and slabs in terms of technical  

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content but also the relationship between  Volume Two and the new Housing Provisions for 2022.

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So starting with 2019 Par 3.2 footings and  slabs, you can see on the right of this Slide  

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the acceptable construction manual if you were  to choose that is to Deemed-to-Satisfy solution  

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you would refer to Australia Standard 2870.  Alternatively and also as a Deemed-to-Satisfy

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solution you can use the acceptable  construction practice which is the one on the  

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left Part 3.22 to Part 3.2.5, this is in 2019. A  point to note within an acceptable construction  

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practice or ACP occasionally there will be  reference to an Australian Standard in this  

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case 2870, that doesn't make 2870 through that ACP  a standalone reference manual it's just something  

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that's referred to as part of those Deemed-to-Satisfy provisions for a particular solution.

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So in NCC 2022 H1D4 of Volume Two I'll demonstrate  through this slide the connection between Volume Two

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and how it takes it to the Housing Provisions  depending on which Deemed-to-Satisfy solution  

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you choose to take. So if we look at H1D4(1)(a) it  will do two things it will take you to either  

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AS 2870 or AS 3600 which is a new inclusion, the  concrete structures code, as a Deemed-to-Satisfy 

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solution if you choose to use the referenced  manuals for your design. If you choose the DtS 

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provisions that were the old ACP provisions of  2019 it will take you to through H1D4(1)(b) directly  

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to Section 4 of the ABCB Housing Provisions. So effectively what we've done is cut out and put  

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in a separate document that being the Housing  Provisions those Deemed-to-Satisfy provisions  

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that currently in 2019 exist all within Volume  Two. H1D4 and now we're looking at subsection (2)  

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this will demonstrate both the technical changes  to footings and slabs but also the connection to  

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Volume Two and the Housing Provisions relative to  limitations. So if you have a look at subclause (2)

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what's happened for footings and slabs, it's  different to 2019 is a reduction in the  

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classification of sites, we've gone from A through  to HD and wound that back to Class A, S or M sites only.

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So there's a limitation now for footings  and slabs within the Housing Provisions to be  

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designed to an A, S or M site only as distinct  from A through to HD in the current 2019 version.

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Other limitations that apply through Volume  Two if you're using the Housing Provisions  

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set out for footings and slabs a  reduction in the size of the slab  

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and this is relative to the reduction  in the choice of site classification. 

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Slabs now have a maximum length of 18 meters, they have a simple geometry, they must have  

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external right angles only and they are  permitted to have one re-entrant corner.

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This slide shows the comparison between 2019  Volume Two and the new Housing Provisions for 2022

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and point out here that in 2019 Part 3.2.2  preparation right through to 3.2.5,

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you'll see we talk about things that are out  of sequence to the construction process and that  

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we talk about the preparation for sites, then we  talk about concrete and reinforcing and then it  

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jumps to site classification and then goes on  to details about footing and slab construction.

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That didn't make too much sense so for 2022  and the Housing Provisions we have an opening  

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application clause that's Part 4.2.1 and then  the first thing is site classification which  

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makes sense and follows a construction  or the design sequence. You design your  

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building based on a site classification  and then you move through excavation for  

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footings and then details about foundations  and concrete and reinforcement. So that's the  

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comparison from 2019 to 2022 noting that 2019  provisions are all contained in Volume Two but  

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the Housing Provisions separate those  out in a separate reference document.

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For footings and slabs, a slight change in  explanatory information, this is one figure  

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that we've put in there it's an explanation of  terms and it just gives details about particular  

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elements of footing and slabs construction, controlled fill, other terms that are common  

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throughout the Deemed-to-Satisfy provisions  and requirements instead of defining them  

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separately or explaining them further in each  substantial provision we provided two figures  

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like this just to set out terminology that's  consistent throughout the the rest of the  

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provisions, it's explanatory information and it's  just there as guidance. One of the main changes in  

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footing in slabs is to stumps, stump footings,  there's a lot of tables that have been added  

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this year for 2022 that you won't find in  2019 currently and they relate to single and  

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double story solutions, tile, metal roofs, a range  of footing sizes, a range of profiles for footing  

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sizes, different floor types and maximum load areas  and with all the acceptable construction practices  

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that have been reviewed anything that's new in  the Housing Provisions particularly in the case  

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of footing and slabs, includes oversight  by a structural engineer. That was a consultancy  

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that has validated any of the solutions that have  been provided in the Housing Provisions for 2022.

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One of the new sections in footing and slabs  and this is in Clause 4.2.22 recessed areas  

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of slabs we've added some Deemed-to-Satisfy provisions there that talk to the recessed  

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depths for slabs particularly in relation to  the configuration of reinforcement. So we've  

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got a different recessed depth for whole  of slab depth, depending on that recess and  

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its relationship to the depth of this lab will  determine the configuration of reinforcing it  

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becomes self-explanatory and it's the function of  that recess versus the depth of the overall slab.