The National Construction Code 2022 (NCC) is to be released shortly and the following article provides some background to changes that may have an impact on the timber industry.
The NCC sets the minimum technical design and construction provisions for Australian buildings. It is published in three volumes with the Building Code of Australia (BCA) published as Volumes One and Two and the Plumbing Code of Australia (PCA) as Volume Three.
It was originally proposed to introduce the new NCC 2022 on the 1st September 2022; however, a recent update issued by the Australian Building Codes Board (ABCB) advised that “…the ABCB will recommend to Building Ministers (at their August meeting) that the publication date for NCC 2022 be further delayed from 1 September 2022, to be not earlier than 1 October 2022.” The ABCB will also provide advice to the Building Ministers in relation to “…transition timeframes for the residential energy efficiency and livable housing provisions.” Advice in relation to these matters will be published on the ABCB’s website (https://abcb.gov.au/news-events) and you can register on the ABCB website (https://abcb.gov.au/register) to be kept informed of ABCB announcements.
Regarding proposed NCC changes, the following key changes that may have an impact on the use of timber products are described. As timber products are primarily used in domestic residential housing, the following summary will focus on the Volume Two changes.
New Code Structure
When the NCC 2022 is formally adopted by the Australian States and Territories, the following Code and Standards will apply to Class 1 buildings (domestic housing and associated buildings):
- NCC Volume Two (contains the governing and administrative matters),
- The new ABCB “Housing Provisions Standard”, and
- The new ABCB “Livable Housing Design Standard”.
The ABCB Housing Provisions Standard is a significant format change to the NCC. This new Standard contains the Acceptable Construction Practices’ (ACPs) content that was previously found in NCC 2019 Volume Two, Section 3. These Practices are referenced by the Deemed-to-Satisfy (DTS) Provisions in Volume Two and provides an NCC compliance pathway.
To make things a little easier, a single, combined version of NCC Volume Two and the new Housing Provisions Standard has also been released.
The Livable Housing Design Standard is referenced by Volumes One and Two for Class 1a buildings (houses and townhouses) and Class 2 sole-occupancy units (individual apartments) which will require the installation of “accessibility features” based on the Livable Housing Design Guidelines silver standard. The aim this change is to increase the stock of accessible housing to support Australians with disability and older Australians, their families and carers.
Some of the specific details include:
- A step free access path to the dwelling entrance which can be from any boundary or a garage/carport or parking space. For raised timber floors, this step free access path can have a one-step ramp or can be provided using a series of ramps with landings.
- The provision for future grab rail installations in toilets, showers and at baths. This can be provided using timber noggings or sheeting. FWPA submitted that the proposed 150 mm nogging depth was not available (140 mm was recommended); however, this can be accommodated by using a combination of 70 mm and 90 mm wall framing i.e., 70 + 90 = 160 mm. If the 150 mm is agreed with the Building Surveyor/Certifier to be considered as a “nominal” dimension, then a 140 mm could be used.
- On the ground floor, one entry door, doors that service habitable rooms, any laundry and one toilet on the entry level, and for doors that service a room having a shower on any level must have a clear doorway width of 820 mm. This will require slightly wider openings in ground floor wall frames, wider door frames and doors.
NCC Volume Two – Class 1 and Class 10 buildings (Residential and non-habitable) and the ABCB Housing Provisions Standard
The NCC Volume Two references the ABCB Housing Provisions Standard which provide DTS solutions (i.e., acceptable construction practices). The key changes for timber-based products and systems include:
- New provisions for window installation that require a minimum gap (10 mm between the top of the window assembly and timber frame) around a window and packing; with guidance on fixing points for windows also provided. This provision may, or may not, influence the size of window openings in timber-frames however should be checked to ensure compliance.
- New DTS Provisions for waterproofing of wet areas. A specific change is to allow the use of fibre-cement sheet as a structural floor as opposed to only compressed fibre-cement sheet.
- Condensation management in Climate Zones 4 to 8. The inclusion of vapour permeance requirements, added exhaust requirements and ventilated roof spaces in Climate Zones 6, 7 and 8. This should help alleviate potential condensation issues which have occurred in roof cavity spaces. These provisions are not required for roofs subjected to Bushfire Attack Level FZ (flame zone); however, FWPA is undertaking some research to investigate potential solutions.
- Details for the attachment of decks and balconies to external walls. FWPA had proposed a change to provide practical timber sizing, fixing and installation details. Specifically, the minimum size of the timber waling plate, to which the deck is attached, has been reduced to a standard/common timber size and typically available fixings have been nominated for the fixing of the timber waling plates to the timber frame.
- New 7-Star energy efficiency provisions. There are a number of ways that energy efficiency can be demonstrated, via; verification using a reference building (VURB), using house energy rating software (e.g. NatHERS) and the DTS elemental provisions. In relation to timber-framing, research undertaken by the University of Melbourne, for FWPA - https://www.fwpa.com.au/images/marketaccess/2021/Final_Report_Timber_framed_housing_the_Path_to_7_Star_PRA526-1920.pdf, identified that the use of house energy rating software provided the most flexibility, and ease, in achieving 7-stars.
- A specific requirement to address thermal bridging in metal-framed roofs, walls and floors has been added. This requires increasing the minimum total R-Value in roofs and ceilings, walls and floors to account for thermal bridging caused by the metal-frame or other ways in which to mitigate the thermal bridging. The aim in addressing thermal bridging effects in housing was to bring up the performance of steel-framed construction to match the thermal performance of timber-framed construction.
There are a range of other changes in the NCC 2022 that would be of interest to the industry and can be found here https://ncc.abcb.gov.au/news/2022/whats-new-about-ncc-2022. FWPA & WoodSolutions are continuing to research solutions and opportunities for industry members and will keep you informed as information becomes available.
If you have any comments or suggestion for areas that could be developed, please contact FWPA at info@fwpa.com.au
Boris Iskra
National Codes and Standards Manager