This video from the 2022 NCC Seminars discusses Part H1 Structure from NCC Volume Two.
My name is Phil Finnimore, I'm one of the Directors in the NCC Management and Standards Team
in the Australian Building Codes Board. Today I'm going to be taking you through the changes to NCC 2022 Volume Two and
the Housing Provisions and the main aim of this is to talk about the connection between Volume Two and
the Housing Provisions and where all of the Deemed-to-Satisfy provisions from 2019 have been moved
into those Housing Provisions and to do that I'll use the examples from the acceptable construction
practice review and go through both structure and the technical changes for the benefit of
the users in the industry. Starting with Part H1 structure, we'll be looking at footings and slabs
but before I start and talk about footing and slabs it's important to note that 2019, you
would understand that we have an acceptable construction practice, that's the black text
in the Volume Two part of the code and then there are the acceptable construction manuals which
generally are reference documents what we've done for NCC 22 is separate those out and put
Volume Two Deemed-to-Satisfy provisions relating to the reference manuals, the Australian Standards
and then limitations and then reference across to the Housing Provisions where the acceptable
construction practices or ACPs have gone. Starting with footings and slabs it was one of the first
ACPs to be reviewed by an ACP review group that worked for the Building Codes Committee, what I'll
do on this these slides is set out the changes to the footing and slabs in terms of technical
content but also the relationship between Volume Two and the new Housing Provisions for 2022.
So starting with 2019 Par 3.2 footings and slabs, you can see on the right of this Slide
the acceptable construction manual if you were to choose that is to Deemed-to-Satisfy solution
you would refer to Australia Standard 2870. Alternatively and also as a Deemed-to-Satisfy
solution you can use the acceptable construction practice which is the one on the
left Part 3.22 to Part 3.2.5, this is in 2019. A point to note within an acceptable construction
practice or ACP occasionally there will be reference to an Australian Standard in this
case 2870, that doesn't make 2870 through that ACP a standalone reference manual it's just something
that's referred to as part of those Deemed-to-Satisfy provisions for a particular solution.
So in NCC 2022 H1D4 of Volume Two I'll demonstrate through this slide the connection between Volume Two
and how it takes it to the Housing Provisions depending on which Deemed-to-Satisfy solution
you choose to take. So if we look at H1D4(1)(a) it will do two things it will take you to either
AS 2870 or AS 3600 which is a new inclusion, the concrete structures code, as a Deemed-to-Satisfy
solution if you choose to use the referenced manuals for your design. If you choose the DtS
provisions that were the old ACP provisions of 2019 it will take you to through H1D4(1)(b) directly
to Section 4 of the ABCB Housing Provisions. So effectively what we've done is cut out and put
in a separate document that being the Housing Provisions those Deemed-to-Satisfy provisions
that currently in 2019 exist all within Volume Two. H1D4 and now we're looking at subsection (2)
this will demonstrate both the technical changes to footings and slabs but also the connection to
Volume Two and the Housing Provisions relative to limitations. So if you have a look at subclause (2)
what's happened for footings and slabs, it's different to 2019 is a reduction in the
classification of sites, we've gone from A through to HD and wound that back to Class A, S or M sites only.
So there's a limitation now for footings and slabs within the Housing Provisions to be
designed to an A, S or M site only as distinct from A through to HD in the current 2019 version.
Other limitations that apply through Volume Two if you're using the Housing Provisions
set out for footings and slabs a reduction in the size of the slab
and this is relative to the reduction in the choice of site classification.
Slabs now have a maximum length of 18 meters, they have a simple geometry, they must have
external right angles only and they are permitted to have one re-entrant corner.
This slide shows the comparison between 2019 Volume Two and the new Housing Provisions for 2022
and point out here that in 2019 Part 3.2.2 preparation right through to 3.2.5,
you'll see we talk about things that are out of sequence to the construction process and that
we talk about the preparation for sites, then we talk about concrete and reinforcing and then it
jumps to site classification and then goes on to details about footing and slab construction.
That didn't make too much sense so for 2022 and the Housing Provisions we have an opening
application clause that's Part 4.2.1 and then the first thing is site classification which
makes sense and follows a construction or the design sequence. You design your
building based on a site classification and then you move through excavation for
footings and then details about foundations and concrete and reinforcement. So that's the
comparison from 2019 to 2022 noting that 2019 provisions are all contained in Volume Two but
the Housing Provisions separate those out in a separate reference document.
For footings and slabs, a slight change in explanatory information, this is one figure
that we've put in there it's an explanation of terms and it just gives details about particular
elements of footing and slabs construction, controlled fill, other terms that are common
throughout the Deemed-to-Satisfy provisions and requirements instead of defining them
separately or explaining them further in each substantial provision we provided two figures
like this just to set out terminology that's consistent throughout the the rest of the
provisions, it's explanatory information and it's just there as guidance. One of the main changes in
footing in slabs is to stumps, stump footings, there's a lot of tables that have been added
this year for 2022 that you won't find in 2019 currently and they relate to single and
double story solutions, tile, metal roofs, a range of footing sizes, a range of profiles for footing
sizes, different floor types and maximum load areas and with all the acceptable construction practices
that have been reviewed anything that's new in the Housing Provisions particularly in the case
of footing and slabs, includes oversight by a structural engineer. That was a consultancy
that has validated any of the solutions that have been provided in the Housing Provisions for 2022.
One of the new sections in footing and slabs and this is in Clause 4.2.22 recessed areas
of slabs we've added some Deemed-to-Satisfy provisions there that talk to the recessed
depths for slabs particularly in relation to the configuration of reinforcement. So we've
got a different recessed depth for whole of slab depth, depending on that recess and
its relationship to the depth of this lab will determine the configuration of reinforcing it
becomes self-explanatory and it's the function of that recess versus the depth of the overall slab.