The following is a Q&A released by B&D Doors in relation to changes to wind rating in the NCC effective May 2019.
What Is The National Construction Code For Wind Rating?
To ensure buildings across Australia are built to a minimum standard that meets necessary safety requirements, the National Construction Code (NCC) stipulates a minimum standard for all buildings to withstand wind. This is determined by measuring two contributing factors: Region and Terrain (outlined below).
All regions of Australia have a wind rating (as outlined in Figure 1 below), being classified into one of four regions.
Figure 1 – High Wind Regions across Australia, as outlined in NCC
The second overlay is the Terrain Category (TC), which factors in the localised topography and infrastructure that impacts the wind rating of a structure (outlined in Figure 2 below).
Figure 2 – Terrain categorisations, as outlined in NCC
A calculation of these two factors determines the overall Wind Classification (rated N1 – 6) for all buildings including houses, sheds, warehouses, etc. within Australia and New Zealand.
What Has Changed In The National Construction Code?
From 1 May 2019, a new amendment to the National Construction Code (NCC) has become effective for all buildings (including houses, warehouses and sheds) built in wind regions A and B in accordance with AS/NZS1170.2-2011. This amendment has been established to help improve the safety of buildings across Australia and New Zealand that are exposed to high wind areas.
The amendment requires that structures designed to this Standard are built to withstand higher internal pressures if the openings are not certified for the applied wind pressure. These changes will affect how sheds (including the doors and windows) are built and designed moving forward. Specifically, the change relates to Section 126.96.36.199 and says:
“The full area of doors, including large access doors (e.g. roller doors) and windows that are normally closed, shall be considered to be openings, unless they are demonstrated to be capable of resisting the applied wind pressures.” (An extract from AS/NZS1170.2-2011 Amendment 4)
It is therefore critical that door and window suppliers (including B&D) now provide products that are rated for the applied wind pressure in Regions A & B, or alternatively, buildings are redesigned to meet these requirements. There will be no changes to wind regions C and D.
What Are The Wind Rating Standards That Must Be Abided By?
There are two standards that must be adhered to in building design:
1. AS/NZS1170.2-2011: Structural design actions – wind actions
2. AS 4055: Wind loads for housing standards
The overarching AS/NZS1170.2-2011 standards apply for all building structures; however housing structures must also adhere to the AS 4055 standards.
How Does This Change Affect B&D Products?
The introduction of new minimum wind rating standards means that a large proportion of roller doors supplied to the shed (prefab) market, including those supplied by B&D, are no longer compliant if the garage door is the only opening.
Whilst we have an existing range of compliant doors (B&D Wind-Lock roller doors and Storm-Shield™ sectional doors), as a matter of priority we are working on longer term solutions to meet the new standards. Please rest assured your business is extremely valuable to us and we are confident we will find a solution that works for you and your customers.
Please note: Orders for projects approved prior to May 1st 2019 can still be supplied using our existing products.
Are There Any Wind-Rated Options Currently Available Through B&D?
Yes. B&D has an existing range of Wind-Lock roller doors and Storm-Shield™ sectional doors which have been independently certified for use in all cyclone-affected regions throughout Australia and meets the new high wind standards in the National Construction Code. Due to sophisticated manufacturing and additional components, our Wind-Lock and Storm-Shield systems (refer Figure 3) come at a higher price than our standard roller doors.
As a matter of critical importance, we are committed to establishing a fit-for-purpose range of roller doors that meets the new standards and we will keep you informed of our progress.
Figure 1.3 – Wind-Lock roller door systems design
What Is B&D Doing To Address The Change?
We understand that there is an immediate urgency to align our product range with the new NCC Standards. We are therefore working to enhance our existing range of standard roller and sectional doors according to the updated Standards, whilst also reviewing our range of premium Wind-Lock and Storm-Shield™ doors to align them to the new Standards and make them more accessible to the broader market.
Rest assured, we will share updates relating to our range of products as they come to hand.
How Does This Change Affect My Business And/Or My Customers?
It is the ultimate responsibility of the Builder to ensure the structure supplied meets the new National Construction Code guidelines for wind rating. It is important that you have the right products to continue to supply your customers to their specifications – and we are confident that B&D can continue to provide suitable solutions in the short and long term.
The market that will be most impacted by this change is the sheds / prefab market due to the construction type and fast construction cycle. We expect less impact in the new housing market given construction of new houses is generally more robust than sheds, and the longer construction cycle means we have several months before builders begin considering door compliance.
Where Can I Find More Information?
The National Construction Code is available to download at https://ncc.abcb.gov.au/ncc-online/NCC. Simply create your own log in to download a free copy.
Put simply, the changes to the NCC wind rating requirements for Wind Regions A and B mean that all openings, including roller doors and sliding doors, will need to be wind rated or the structure is to be upgraded. This means that any shed that is to have a non-wind rated roller door or sliding door will need to be designed and engineered as if it were an open side/front/end shed.
When roller doors are to be used, Carimor Sheds will determine whether the shed will have wind rated roller doors, if available, or upgrade the structure. Costs may come into this as it may be cheaper to use wind rated roller doors than upgrading the structure and vice versa.
When sliding doors are to be used, Carimor Sheds will upgrade the structure as the sliding doors manufactured by Carimor Sheds are not wind rated and will not be for the foreseeable future.