Windows and glazing for modular buildings are the single most demanding interface in a factory built module. They have to carry wind load, keep water out, resist human impact, and pull their weight on your energy rating, all at once, and all of it has to be proven to a building surveyor before an occupancy permit is issued. For offshore pre-cladded modules the glazing arrives already installed, flashed and sealed, which is an advantage when the paperwork behind it is in order and a liability when it is not. This guide sets out the Australian standards that govern windows and external glazing, how they apply to steel framed modular construction, and the evidence a surveyor will ask for in 2026.
EcoPrestige Prebuilt supplies turnkey, fully pre-cladded steel framed modules that are engineered to Australian standards and manufactured offshore in our 50,000 square metre in-house production facility. The windows and glazed doors are factory installed as part of that scope. Understanding the compliance chain below is how a builder or developer turns a good price into a defensible building.
The standards that govern windows and glazing in Australia
Three Australian Standards do most of the work, and the National Construction Code calls them up.
- AS 2047:2014 Windows and external glazed doors in buildings. This is the performance standard for the window as a manufactured assembly. It covers structural adequacy under wind, water penetration resistance, air infiltration and operating force.
- AS 1288:2021 Glass in buildings, selection and installation. This governs the glass itself, how it is selected for wind load and human impact, and how it is installed, including balustrades, overhead glazing and safety glazing locations.
- AS/NZS 2208 Safety glazing materials in buildings. This defines and marks Grade A safety glazing material, which is toughened or laminated safety glass used where human impact is a risk.
The way these connect to the Code depends on the building class. For apartments, hotels and other Class 2 to 9 buildings, NCC Volume One references AS 1288 and AS 2047 for glazing and weatherproofing. For Class 1 homes and the like, the NCC Housing Provisions carry a dedicated glazing part with deemed to satisfy tables for perimeter glazing wind classes and human impact zones. EcoPrestige modules are delivered across NCC Class 1a, 2, 3 and 9b, so in practice both routes are relevant depending on the project.
AS 2047: window performance testing for your wind region
Every window and external glazed door in an external wall is required to be tested to AS 2047, with narrow exceptions for non-vertical installations, site constructed windows and heritage windows. Testing is carried out to the AS 4420 series and covers five things: deflection under wind load (AS 4420.2), operating force (AS 4420.3), air infiltration (AS 4420.4), water penetration resistance (AS 4420.5) and ultimate strength (AS 4420.6). A window that passes is given a rating.
That rating is a design wind pressure, expressed at both a serviceability limit state and an ultimate limit state. The number has to match, or exceed, the design wind pressure at your site. For Class 2 to 9 buildings the design wind pressure is derived from the wind actions standard AS 1170.2. For housing it is commonly expressed as a wind classification such as N1 to N6, or C1 to C4 in cyclonic regions, under AS 4055. The practical point for a modular project is that a window rated for a sheltered suburban site is not the same window you need on an exposed or coastal one. The rating is nominated to suit the site, and the manufacturer verifies that the supplied window meets it.
This is where factory production earns its keep. Because EcoPrestige windows are ordered and installed as part of a controlled production run, the AS 2047 rating for each opening can be specified against the project wind pressure and documented before the module leaves the line. Cyclonic regions carry additional requirements for debris impact and repeated loading, which is a separate conversation covered in our guide to cyclone rated modular buildings for wind regions C and D.
AS 1288 and AS 2208: safety glass and human impact
AS 2047 rates the window assembly. AS 1288 selects the glass inside it. The standard sets the minimum glass type and thickness for the wind load, and it sets where Grade A safety glazing material to AS/NZS 2208 is mandatory to protect people from impact.
Safety glazing locations include glazed doors and the side panels next to them, low level glazing that a person could fall against, glazing in bathrooms, ensuites and spa rooms, frameless shower screens, and full height glazing. In these locations the glass must be toughened or laminated safety glass and it must be permanently marked so an inspector can identify it. A frameless glass shower screen in an EcoPrestige bathroom module, for example, is Grade A safety glass selected and installed to AS 1288, not ordinary glass. Getting the safety glazing schedule right at design stage is far cheaper than replacing marked glass after a module is finished.
Wind, water and weatherproofing at the window
The most common defect in any building, modular or site built, is water getting in around a window. The NCC sets a performance requirement that external walls must prevent the penetration of water that could cause unhealthy or dangerous conditions, or loss of amenity. AS 2047 proves the window itself resists water to its rated pressure. The rest of the job is the interface: the head, jamb and sill flashings, the sill tray, the sealant joints and the way the window ties into the wall wrap and cladding.
In a pre-cladded module this interface is built and sealed in the factory, under cover, by the same team every time, then the module is made weathertight before it is transported. That control is one of the reasons a fully finished modular envelope can be more consistent than a window installed on a wet and windy site. It also connects directly to condensation and durability. A well sealed window reduces uncontrolled air paths, which supports the vapour management approach set out in our guide to condensation management in steel framed modular buildings, and the wet area detailing described in our waterproofing compliance guide.
Energy: how windows drive your NatHERS and Section J result
Windows are usually the weakest thermal element in a wall, so they have an outsized effect on energy compliance. Under NCC 2022 a Class 1 home must reach a 7 star NatHERS rating for the building fabric, and the star rating is highly sensitive to the window U-value and Solar Heat Gain Coefficient, the orientation of the glazing and the shading over it. For Class 2 to 9 buildings the equivalent obligation sits in Section J, whether met by the deemed to satisfy provisions or a verification method.
Windows are rated for energy through the Window Energy Rating Scheme, which publishes the U-value and SHGC that an energy assessor feeds into the model. Specifying the glazing performance early, rather than accepting a default, is what lets a modular design hit its target without oversizing the mechanical systems. This is the same logic set out in our guide to energy efficient modular buildings and the 7 star NatHERS requirement, and the window is where much of that result is won or lost.
The factory glazing advantage and the site interface
Honesty about scope is what separates a supplier who gets found out from one who does not. EcoPrestige supplies the module with its windows factory installed, rated and documented. The head contractor or registered building practitioner is the builder of record on the project, holds the building permit and carries responsibility for the completed building, including any site built elements and the joints between modules.
At the site interface there are a small number of glazing related items that are completed and checked on site rather than in the factory. These include sealing and flashing the joints between modules, making good any glazing that adjoins site built structure, and confirming that nothing was damaged in transport or craning. EcoPrestige offers three ways to work with this: modular supply only, supply plus an EcoPrestige installation crew, or a design and build coordinator role under AS 4300. Naming these interface items in the contract, and allocating them in writing, is how the price stays clean and the compliance stays whole.
Evidence of suitability: what your surveyor will want
Under the NCC evidence of suitability provisions, a building surveyor accepts glazing on documentary evidence, not on trust. For windows and glazing in an offshore pre-cladded module, the package that supports an occupancy permit typically includes the following.
- The AS 2047 test report or rating certificate for each window type, showing the rated design wind pressure meets the site value.
- The AS 1288 glazing selection, confirming glass type and thickness for wind load and human impact, with the safety glazing schedule.
- Evidence that safety glazing is Grade A material to AS/NZS 2208, with the permanent marking.
- The WERS or equivalent window energy data used in the NatHERS or Section J assessment.
- The installation and flashing details showing how the window is sealed into the wall.
EcoPrestige assembles this glazing evidence as part of the wider compliance file, which is described in our evidence of suitability guide for modular buildings and sits alongside the structural certification and the building permit and surveyor inspection process. A surveyor who is handed a complete, labelled set of window evidence has very little reason to hold up a certificate.
Windows and glazing for modular buildings: bringing it together
Windows and glazing for modular buildings are not an afterthought bolted on at the end. They are a designed, tested and documented system that has to satisfy AS 2047 for wind and water, AS 1288 and AS/NZS 2208 for glass and safety, and the NCC for weatherproofing and energy. The advantage of a fully pre-cladded steel framed module, delivered around 30 percent faster than typical modular suppliers and backed by a 12 year structural and 12 month materials warranty, is that this system is built and proven in a controlled factory before it reaches your site. The work for the builder is to specify the ratings to the site, allocate the interface, and keep the evidence together. Do that, and the glazing stops being a risk and starts being one more part of the building that is already signed off.
To go deeper on the compliance chain, see our overview of NCC 2022 compliance for modular buildings across Class 1a, 2, 3 and 9b, or request the EcoPrestige builder pack.