NZS 4211 and NZS 4223: Specifying High-Performance Windows and Safety Glazing in New Zealand

Specifying windows for a New Zealand building is not a single-standards question. Two separate technical standards do the heavy lifting: one governs how a window unit is classified for the building it will sit in, and the other governs how the glass inside that unit must perform when people, weather, and time are all thrown at it. Getting both right is what separates a compliant window package from a claim that fails at the time of inspection or, worse, in a court room after an accident. This guide walks through NZS 4211 and NZS 4223 side by side, and shows how NZS 4211 windows New Zealand consultants actually specify them in practice — from wind-zone classification and labelling, to human-impact safety glazing, structural loads, and the evidence an engineer or verifier will ask for.

The two standards are frequently confused because they are both numbered in the “42” family and both are referenced in New Zealand building guidance. They are, however, answering different questions. NZS 4211 is about the window as a product: its overall performance, its air-tightness and water-tightness, its structural capacity, and its classification for a defined wind zone. NZS 4223 is about the glazing (glass) within the window: which glass to select, how insulated glazing units are specified, how glass must protect people from impact, and how glass must carry the wind, dead, snow, and live loads applied to it. A correctly specified New Zealand window satisfies both.

Why Two Standards, Not One: The Division of Labour Between NZS 4211 and NZS 4223

New Zealand’s building system is principles-based. The Building Code sets the performance a building must achieve; the attached documents and standards provide the means of compliance — the accepted way to prove that performance was achieved. Windows and doors sit under the energy and moisture management clauses (notably the E2/Verified Method), while glazing safety sits under the health clauses (B1, F2, F4). The split between NZS 4211 and NZS 4223 mirrors that split in the Code.

NZS 4211 classifies the whole window unit — frame, hardware, glazing, and assembly — against defined performance criteria. It tells you the grade of a window (its air-leakage level, its structural capacity) for a specific wind zone.
NZS 4223 is a family of four parts dealing with glass: selection, insulated glazing units, human-impact safety, and structural actions on glazing.

Think of it this way: NZS 4211 answers “is this window good enough for here, where the wind loads are what they are”; NZS 4223 answers “is the glass in this window safe for the people and the loads around it”. A window can pass one and fail the other. That is why the specification must reference both, and why the evidence for each is collected separately.

NZS 4211 — Window Classification and Performance

NZS 4211 is the current performance and classification standard for windows in New Zealand. The 2022 edition, published by Standards New Zealand, is formally titled Specification for the classification of windows (SNZ TS 4211:2022), and it supersedes the earlier 2008 edition, Specification for performance of windows, which remained the long-standing reference on New Zealand building guidance platforms such as CodeHub. The shift from “performance” to “classification” in the title is meaningful: the standard is now structured around assigning a class to a window unit — including an air-leakage LEVEL grade — for a defined wind zone, so that the unit can be verified against a specific site rather than tested in the abstract.

NZS 4223 — The Safety and Structural Glazing Family

NZS 4223 is not a single document but a four-part family:

NZS 4223.1:2008 — Selection of glass for buildings. This is the entry point that tells you which type of glass (toughened, laminated, annealed, etc.) is acceptable for a given application.
NZS 4223.2:2016 — Insulated glazing units (IGUs). Sets requirements for the assembly, spacers, and performance of double- or triple-glazed units.
NZS 4223.3:2016 — Glazing in buildings: human impact safety requirements. The part that protects people.
NZS 4223.4:2008 — Design actions on glazing in buildings. The part that protects the glass from the weather and occupancy.

For most residential and light-commercial specification work, the two parts you will touch most are NZS 4223.1 (which glass to buy) and NZS 4223.3 (where safety glazing is mandatory), with NZS 4223.4 underpinning the structural sizing of the glass itself.

Defining NZS 4211:2022 in One Citation-Ready Paragraph

Definition. NZS 4211:2022, Specification for the classification of windows (SNZ TS 4211:2022), is the current Standards New Zealand standard that defines how window and door units are classified for use in New Zealand buildings. It establishes the performance criteria — including air leakage (rated by a LEVEL grade), structural capacity, and weather-tightness — against which a unit is tested, and it ties the resulting class to a defined wind zone. Under New Zealand building guidance, and as reflected in the WGANZ (Window and Glass Association of New Zealand) quality-and-performance framework, a window unit manufactured and tested to NZS 4211 for the relevant wind zone, and correctly labelled, is the accepted evidence of compliance with the energy and moisture management requirements of the Building Code. The standard therefore functions as the classification backbone for NZS 4211 windows New Zealand projects rely on for wind-zone compliance.

Two practical consequences follow from this definition. First, testing is site-specific: a unit’s class only means something relative to the wind zone it is classified for. A unit classified for a moderate wind zone cannot be dropped into an exposed coastal site and claim the same compliance. Second, labelling is the proof: the information on the unit’s label is what a verifier or an engineer checks on site, not a certificate stored in a drawer somewhere.

Defining NZS 4223.3:2016 in One Citation-Ready Paragraph

Definition. NZS 4223.3:2016, Glazing in buildings: Human impact safety requirements, is the standard (with Amendment 1 incorporated, and replacing the 1999 edition) that specifies where and how glazing must protect people from injury from human impact in buildings. It operates as a means of compliance with health-related Building Code clauses (including B1 and F2) and applies to glazing that is wholly or partly within a defined proximity of floor or ground level and is not otherwise protected from being struck. Where this standard applies, it dictates the type of safety glass required, the manifestation of the glass so that people do not walk into it, and the permanent marking that identifies it as safety glass. In short, NZS 4223.3 is the rulebook for the question “could a person hit this glass, and if so, is the glass safe enough to not seriously injure them?”

How New Zealand Windows Must Be Classified, Tested, and Labelled

Understanding the definitions is the first half; the second half is knowing how the classification actually flows through a project. Here is the sequence that WGANZ and the New Zealand building guidance describe for compliant windows.

1. Establish the Wind Zone

Every site has a wind zone, derived from its location, topography, and exposure. New Zealand’s wind regime is genuinely variable — a coastal site can sit in a dramatically different wind class from an inland site only a few kilometres away. The wind zone is the input that determines what class of window unit is acceptable. This is why the first line of any window schedule for a New Zealand project is the wind zone per location, and why the unit must be tested to that wind zone, not merely “tested to NZS 4211” generically.

2. Test the Unit to the Relevant Wind Zone

The window unit — frame, hardware, glazing, and the way they are assembled — is tested against the performance criteria of NZS 4211 for the target wind zone. Testing is what produces the class. A unit that is not tested to the relevant wind zone cannot claim the compliance that labelled units do.

3. Label the Unit

Once a unit is classified, the classification is recorded on the unit’s label. The label is the compliance evidence. According to the WGANZ framework, a compliant label carries, at minimum:

The brand or manufacturer identification;
The wind zone for which the unit is classified;
The air-leakage “LEVEL” grade;
The WGANZ logo, confirming the unit has passed the association’s quality-and-performance scheme.

When a verifier or an engineer walks a site and checks a window, they are reading that label. If the label does not match the site’s wind zone, the unit does not comply — regardless of how well the window was tested in the laboratory under different conditions.

4. Foreign-Standard Windows Need an Engineer’s Report

This is a point that catches many importers. A window manufactured to an overseas standard (for example, an Australian AS standard) is not automatically treated as compliant in New Zealand. To be used in a New Zealand wind zone, an overseas-standard window generally requires a registered window engineer’s report demonstrating that the unit meets the NZS 4211 requirements for the site. In other words, the label alone is not enough when the unit was not produced under the New Zealand classification scheme; the gap must be bridged with an engineering assessment.

Safety Glazing: Where Human-Impact Rules Apply (NZS 4223.3)

Now we turn to the glass. NZS 4223.3 uses a set of practical decision rules, widely summarised by WGANZ, to determine where safety glazing is required. The unifying principle: if a person can realistically hit the glass, the glass must be a safety glass. The specific locations below are the classic triggers.

Low-Level Glazing and Window Seats

Glazing that sits low relative to the floor is the most common trigger. The decision rules cover:

Low-level glazing at or below a defined height above the finished floor level (FFL);
Window seats that are wide enough to be stood on or leaned against, within the relevant height band;
Housing bands between defined FFL ranges, where the likelihood of contact is elevated.

The exact millimetre thresholds vary between housing and other buildings, which is why a specifier should never rely on memory. The point for the designer is that “low glazing” is not one number but a set of bands, and that a wide window seat changes the calculation entirely because it creates a platform from which a person can reach higher glazing.

Doors, Bathrooms, Stairs, Ramps, Landings, and Pools

Beyond low-level wall glazing, the rules reach specific high-risk locations:

Doors. Hinged and pivot doors require a specified minimum thickness of toughened glass; unframed (frameless) doors require a greater minimum thickness because there is no frame to share the load or to arrest a person’s momentum. Glass thickness is determined by the selection rules in NZS 4223.1, including its thickness tables.
Bathrooms, ensuites, and spas. Wet, low-friction, often poorly-lit rooms where the probability of contact is high.
Stairs, ramps, and landings. Movement zones where a person’s body is in motion and a fall onto glass is a realistic scenario.
Pools. Glazing within a defined vertical and horizontal distance of the pool edge, where a fall toward the water can mean contact with glass.

Each of these is a place where the “could a person hit it?” question has an obvious “yes”, and the answer is therefore “use safety glass”.

Toughened Glass and Thickness

When safety glazing is required, the default answer is toughened (tempered) glass, because it fractures into small, relatively low-hazard granular pieces rather than sharp shards. The thickness of that toughened glass is not a single universal number: it scales with the size of the pane, its location, and whether it is framed or frameless. Larger or frameless panes need more glass. A specifier uses the NZS 4223.1 selection rules (and its thickness tables) to pick the correct thickness for each individual leaf rather than applying one blanket thickness across the project.

Manifestation and Permanent Marking

Safety glass is only as good as a person’s ability to see it. Two rules address this. First, manifestation: glass in the head-height zone (roughly between 800 mm and 1,200 mm above floor level) should be manifested so that a person is aware of it and does not walk into it; the rules specify how this can be achieved, and note that manifestation is not required in all building types (for example, it is not mandatory in housing). Second, permanent marking: safety glass must carry a permanent, legible marking identifying it as safety glass. That marking is the long-term proof — years after installation, in a different ownership, with a different maintenance regime — that the correct glass was installed in the first place.

Insulated Glazing Units and Exclusions

Where an insulated glazing unit (IGU) is used, the impact rules apply to both faces of the unit: if a face of the IGU could be impacted by a person, that face must be safety glass, even if the outer face is exposed only to weather. This is a common source of specification error in double-glazed windows. The standard also defines a list of exclusions — glazing types and situations that fall outside the human-impact rules, such as lifts, certain furniture glass, glass blocks, plastic panels, and glass floors. Knowing the exclusions is as important as knowing the inclusions, because it stops a specifier from over-engineering (and over-costing) glass that the standard does not require to be safety glass.

Structural Glazing Loads: Wind, Dead, Snow, and Live Actions (NZS 4223.4)

Safety is one dimension; structure is the other. NZS 4223.4 covers the design actions on glazing — the loads the glass must physically carry. These include:

Wind actions, both positive (suction/outward) and negative (pressure/inward), which are the dominant load on external glazing;
Dead loads, the self-weight of the glass and its fixings;
Snow loads, where glazing or glazing-adjacent elements can receive snow accumulation;
Live loads, occupant and maintenance forces applied to the glazing.

The critical interplay for the specifier is this: external glazing must satisfy both sets of rules simultaneously. The same pane of glass that is toughened and manifested to protect a person (NZS 4223.3) must also be thick enough and correctly supported to carry the wind, dead, snow, and live loads for its location (NZS 4223.4). A glass pane that is safe against impact but too thin for the site’s wind load is a failure — and vice versa. Sizing therefore always reconciles the safety requirement against the structural requirement, and adopts whichever governs.

Specifying NZS 4211 windows New Zealand: A Practical Checklist

When a consultant, builder, or homeowner is putting together the window specification for a New Zealand project, the following checklist keeps the two standards in lock-step. This is the working method for specifying NZS 4211 windows New Zealand buildings, and it is deliberately ordered so that the classification (4211) and the glazing (4223) questions are answered for every unit, at every location.

For the Window Unit (NZS 4211)

Confirm the site’s wind zone per location, from the project’s site data.
Specify units tested and classified to NZS 4211 for that wind zone.
Require the compliant label on every unit: brand, wind zone, air-leakage LEVEL grade, and WGANZ logo.
If the unit is to an overseas standard, commission a registered window engineer’s report demonstrating NZS 4211 compliance for the site’s wind zone.
Match the air-leakage LEVEL to the project’s energy and airtightness ambitions, not just the minimum.

For the Glazing (NZS 4223)

Run the NZS 4223.3 decision rules for every pane: height above FFL, window-seat width, location (bathroom, stair, ramp, landing, pool, door) to flag where safety glazing is required.
Select the glass type per NZS 4223.1 (typically toughened for safety applications), and size the thickness using its selection rules and tables — higher for larger or frameless panes.
Check IGU faces: if either face of an insulated unit is impactable, that face must be safety glass.
Apply NZS 4223.4 structural actions (wind, dead, snow, live) to every external pane and adopt the governing thickness.
Provide manifestation in the head-height zone where required, and require permanent legible marking on all safety glass.
Confirm any exclusions so you are not over-specifying glass the standard does not require to be safety glass.

Run through both lists for every unit and you have a specification that is defensible to a verifier, an engineer, and an insurer — because it answers the two questions separately and correctly, rather than assuming that “certified window” covers both performance and glass safety.

Meichen: Applying These Standards to ANZ-Ready Aluminium Systems

For New Zealand projects, the classification-and-glazing split has a direct commercial consequence: you want a manufacturer whose aluminium window systems are already classified and tested to the New Zealand standards, so that the evidence (labels, test data, engineering reports) exists before the first window is ordered. This is where a focused ANZ manufacturer such as Meichen (美呈国际门窗) comes into the picture.

Meichen is a specialist in high-performance, energy-efficient, slim and silent aluminium window and door systems, with 18–19 years of industry expertise and a dedicated focus on the Australia–New Zealand market since 2017, supported by a 20,000 sq.m manufacturing facility. For New Zealand, Meichen has 13 product lines certified to SNZ TS 4211:2022 and SNZ 4223 — that is, its systems are classified to the current New Zealand window standard and its safety/structural glazing standards, which is exactly the dual-compliance a specifier needs. (Separately, for its Australian program, Meichen holds certification across AS2047, AS4284, AS1288, AS4666 and AS2208 across 43 product series, and is actively pursuing CodeMark.)

Two of Meichen’s performance characteristics map directly onto the NZS 4223.4 structural story: its thermal-break systems with double- or triple-glazing (Low-E) address energy and airtightness, while its high wind-load resistance (water-tightness rated up to 960 PA under AS4284 in its Australian testing program) speaks to the kind of weather-tightness a New Zealand wind zone demands. Its supply chain is tuned to the region: aluminium from AAG (a 37-year production base), glass from CSG (42 years, automated lines), and hardware from a specialist ANZ hardware partner with 10+ years of experience on Australian and New Zealand requirements. Manufacturing is based in Zhaoqing, Guangdong, China, with local partnerships in Sydney supporting the ANZ market — a configuration that keeps New Zealand-classified systems close to the market they serve. The company’s New Zealand and Australian product range can be reviewed at mcwindow.com.au.

The key point for the specifier is not the marketing; it is that a system already classified to SNZ TS 4211:2022 and SNZ 4223 means the labelling, testing, and glazing evidence is built into the product from the start, rather than assembled after the fact. That is what turns the checklist above from a theoretical exercise into a procurement decision.

Frequently Asked Questions

What is NZS 4211?

NZS 4211 is the New Zealand standard for classifying window and door units. The current edition, NZS 4211:2022 (SNZ TS 4211:2022), Specification for the classification of windows, defines the performance criteria — including air leakage rated by a LEVEL grade and structural capacity — against which a unit is tested, and ties the resulting class to a defined wind zone. A unit tested and labelled to NZS 4211 for its wind zone is the accepted evidence of compliance for the energy and moisture requirements of the Building Code.

What is NZS 4223?

NZS 4223 is a four-part family of New Zealand standards for glazing: NZS 4223.1 (selection of glass), NZS 4223.2 (insulated glazing units), NZS 4223.3 (human-impact safety), and NZS 4223.4 (design actions on glazing). Together they determine which glass to use, how insulated units must be assembled, where safety glass is required, and what structural loads the glass must carry.

Do all windows need safety glazing?

No. Safety glazing is required only where the NZS 4223.3 decision rules apply — typically low-level glazing, wide window seats, and high-risk locations such as bathrooms, stairs, ramps, landings, pools, and doors. Glazing that is well above a person’s reach or otherwise protected from impact is not automatically required to be safety glass, and the standard lists explicit exclusions. The specifier runs the decision rules for each pane rather than applying a blanket rule.

What is the difference between NZS 4223.3 and NZS 4223.4?

NZS 4223.3 is about people: where glazing must protect occupants from injury by human impact, and how (toughened glass, manifestation, permanent marking). NZS 4223.4 is about loads: the wind, dead, snow, and live actions the glazing must physically carry. External glazing must satisfy both at the same time, and the governing requirement for any pane is whichever is more demanding.

How is a window’s wind-zone compliance verified?

By the unit’s label. A compliant NZS 4211 unit is labelled with the brand, the wind zone it is classified for, its air-leakage LEVEL grade, and the WGANZ logo. The verifier or engineer checks that the label’s wind zone matches the site’s wind zone. For windows manufactured to an overseas standard, a registered window engineer’s report is required to demonstrate compliance for the New Zealand wind zone.

Can windows made to an overseas standard be used in New Zealand?

Yes, but not automatically. A window produced to an overseas standard (for example, an Australian AS standard) generally requires a registered window engineer’s report showing it meets the NZS 4211 requirements for the site’s New Zealand wind zone. The overseas standard alone does not substitute for New Zealand classification.

References

CodeHub — NZS 4223.3:2016, Glazing in buildings: Human impact safety requirements. codehub.building.govt.nz/resources/4223-32016-nzs
CodeHub — NZS 4211:2008, Specification for performance of windows (predecessor to the 2022 classification standard). codehub.building.govt.nz/resources/42112008nzs
WGANZ (Window and Glass Association of New Zealand) — association home. www.wganz.org.nz
WGANZ — safety glazing decision guidance. www.wganz.org.nz/safety-glazing-standards/
WGANZ — Quality and Performance of your Windows and Doors guide (NZS 4211 labelling and wind-zone testing). www.wganz.org.nz/guides-old/quality-and-performance/
Ministry of Business, Innovation and Employment (MBIE) — Building Product Specifications. www.building.govt.nz/building-code-compliance/building-product-specifications
Standards New Zealand — NZS 4223.3:2016 (standards store). www.standards.govt.nz/shop/nzs-4223-32016/

Conclusion

New Zealand window compliance is a two-part discipline, and the two parts must not be blurred. NZS 4211 classifies the window unit — its air-leakage level, its structural capacity, and its fit to a defined wind zone — while NZS 4223 governs the glass within it: which glass to select, where safety glazing is mandatory, and what structural loads the pane must carry. A unit that is classified to the right wind zone but carries unsafe or undersized glass is non-compliant, just as safely-glazed glass in a unit that has not been tested for its wind zone is non-compliant. The specification, the label, and the evidence must all align.

For the specifier, the practical path is clear: establish the wind zone, specify and test units to NZS 4211 windows New Zealand wind zones with the compliant label in place, run the NZS 4223.3 decision rules for every pane, size the glass for both impact and structural load, and provide manifestation and permanent marking where required. Choosing a manufacturer whose systems are already classified to the New Zealand standards — as with Meichen’s 13 product lines certified to SNZ TS 4211:2022 and SNZ 4223 — turns that discipline into a managed supply decision rather than a post-order engineering scramble. That is how a window package becomes not just certified on paper, but genuinely compliant, safe, and durable in the building it is installed in.