Aluminium Window Mock-Up Testing: Water, Air and Installation Quality Assurance

A project mock-up is the point where a window specification stops being a document and becomes a physical assembly that a site team can inspect, test and copy. It is a rehearsal for the real facade: the same frame, the same glazing, the same wall build-up and the same trades, put together in the same order, before hundreds of openings are manufactured and installed. When it is planned well, the mock-up exposes the awkward details while they are still cheap to change. When it is treated as a formality, it becomes a photograph in a handover folder and the same defects are repeated across the building.

This article sets out how aluminium window mock-ups are used for water, air and installation quality assurance. It covers why the mock-up exists, where its boundaries should be drawn, what to observe during water and air testing, how interfaces, seals, drainage and glazing behave under test, what installation records should capture, and how defects should be closed out. It also explains how the Australian and New Zealand standards frameworks fit together, including the National Construction Code, the Australian Building Codes Board, AS 2047, AS 4284, AS 1288, AS 4666, SNZ TS 4211:2022 and SNZ 4223.

Why a Project Mock-Up Exists

A type test and a project mock-up answer different questions. A type test asks whether a window system can achieve a defined performance level when a specimen is prepared and tested under controlled conditions. A project mock-up asks whether the project team can build that system into this particular wall, on this particular building, with these particular interfaces, and have it perform as intended. The first is evidence about a product. The second is evidence about a delivery process.

That distinction matters because most failures on real buildings are not failures of the extrusion or the glass. They are failures of the joints between packages: the frame-to-wall seal, the flashing lap, the membrane termination, the sealant that was applied over dust, the weep slot that was blocked by a well-intentioned bead of silicone, or the fixing that was moved because a reinforcement bar was in the way. None of those defects can be found in a product brochure. A mock-up is designed to find them.

A well-run mock-up serves several purposes at once. It confirms that the detail is buildable with the trades and access available on site. It tests the sequence of work, especially where window installation must follow the weather barrier but precede the internal lining. It gives the approving authority, the consultant and the client a shared physical reference for workmanship. It establishes hold points and inspection criteria that can be applied to every subsequent opening. It also creates a known-good benchmark, so that a site inspector can say with confidence that an installed window does or does not match the standard set by the mock-up.

The mock-up should therefore be attended by the people who will actually deliver the work, not only by sales staff. The window installer, the builder, the waterproofing or membrane applicator, the cladding contractor, the facade consultant and the project manager all need to see the same assembly and agree on who seals what, who flashes what and who inspects what. A mock-up that is built by a specialist team flown in for the day proves very little about the team that will install the remaining openings.

Where the Mock-Up Boundary Begins and Ends

Every mock-up needs a written boundary statement before it is built. The statement should define the specimen, the surrounding construction, the interfaces included, the tests to be performed, the acceptance criteria and the records to be produced. Without that statement, a successful test can be claimed for work that was never actually covered, and a failed test can be blamed on scope that was never agreed.

The physical boundary is the first issue. A window tested on its own, fixed into a rigid steel frame, says something about the window but very little about the wall junction. A mock-up that includes the real wall build-up, the real opening, the real flashing, the real membrane and the real internal lining says much more, because it reproduces the paths that water and air actually take. The boundary should be drawn wide enough to include every interface that the window depends on, and narrow enough that the result can still be attributed to a definable assembly.

The performance boundary is the second issue. A mock-up may be a visual and installation mock-up, a water and air performance mock-up, or both. If pressure testing is included, the test standard, the specimen configuration and the test laboratory or site arrangement must be stated. If testing is not included, the mock-up cannot be used to support a performance claim; it can only support workmanship and buildability. Confusing the two is one of the most common sources of dispute on facade projects.

The responsibility boundary is the third issue. Water does not respect trade packages. A leak observed at the internal sill may have entered at the head flashing, travelled through the wall cavity and emerged far from its source. The boundary statement should allocate responsibility for each interface and nominate who will investigate, rectify and re-test when an observation does not meet the agreed criteria. It should also record what is explicitly excluded, such as a different wall type in another part of the building or a different window configuration that is not represented by the specimen.

The Standards Framework Behind the Test

The National Construction Code and the ABCB

In Australia, the National Construction Code sets the performance requirements that a building must satisfy, including weatherproofing, structural sufficiency, fire safety, energy efficiency and amenity. The Australian Building Codes Board develops and maintains the code and its supporting material. For a window package, the practical question is how the proposed product and installation demonstrate compliance with the relevant performance requirements for the specific project, in the specific climate and wind region, under the edition of the code that applies at the time of approval.

The code is performance-based, which means compliance can be demonstrated through different forms of evidence. Test reports, product technical statements, engineering assessment and installation documentation all have a role, but they must be consistent with one another. A report for a different configuration, a different size or a different glazing make-up is not evidence for the assembly being installed. The mock-up is the point at which that consistency is checked in three dimensions.

AS 2047 and AS 4284

AS 2047 is the Australian product standard for windows and doors in buildings. It defines performance characteristics and the framework within which a window system is described and assessed. AS 4284 is the companion test standard for the performance of windows and external doors, covering the laboratory test methods used to evaluate water penetration resistance, air infiltration and wind load resistance. Together they form the technical basis on which a window’s claimed performance can be compared with a project’s requirements.

The knowledge base for this article records water tightness of up to 960 Pa under AS 4284 as the upper end of the tested range for the relevant aluminium systems. That figure is useful because it shows the order of magnitude that a high-performance system can reach, but it must never be applied to a project as a generic promise. The number belongs to a specific specimen, a specific size, a specific configuration and a specific test report. A mock-up is how the project confirms that the assembly it is actually building sits within that tested envelope rather than assuming it does.

AS 1288 and the glazing package

AS 1288 deals with glass in buildings, including the selection of glass types and the structural and installation requirements that apply to them. It is not a window standard, but it governs the glass that the window must carry, and it interacts with safety glazing requirements under AS 2208 where people are likely to come into contact with glass. In a mock-up, AS 1288 shows up in the details: how the glass is supported, how much edge clearance is provided, how setting blocks are positioned, how the bead or gasket holds the pane, and whether the glazing system is drained and ventilated as designed.

AS 4666 and installation

AS 4666 is the Australian standard for the installation of windows and doors. It matters because a product that performs in a laboratory can fail in a building if it is fixed, packed, flashed or sealed incorrectly. Installation is not a generic building activity that can be left to site preference. It is a defined process with requirements for the substrate, the fixing, the interface, the seal and the sequence of work. The mock-up is where the installation method statement is proved against the standard and against the reality of the wall.

SNZ TS 4211:2022 and SNZ 4223 in New Zealand

New Zealand projects operate under a separate framework. SNZ TS 4211:2022 is the New Zealand technical specification for window performance, and SNZ 4223 is the New Zealand glazing standard. They are not interchangeable with the Australian documents, and a project on one side of the Tasman should not rely on evidence prepared only for the other. Wind, climate, detailing practice, building consent processes and testing expectations differ. A New Zealand mock-up should be planned around the New Zealand specification and glazing requirements, with evidence that matches the consenting pathway and the actual installation conditions.

Water Observations During the Mock-Up

Water testing is often reduced to a pass or fail at the end of the exercise, which wastes most of the information the test produces. The valuable observations are about where water appears, when it appears, how it travels and whether it clears. A window can keep water off the internal face and still be behaving badly, for example by trapping water in a cavity, wetting insulation, or allowing water to stand in a track where it will eventually find a path or promote corrosion.

The first observation category is direct leakage. Water appears on the internal face, at a gasket, at a corner, at a mullion, at a hinge or at a fixing. The observer should record the location precisely, the stage at which it appeared, and whether it continued after the pressure was released. A leak that stops immediately is different from a leak that keeps running, because the second suggests a reservoir or a path that is still draining.

The second category is concealed leakage. Water enters the wall cavity or the frame cavity and does not immediately show on the inside. This is the more dangerous outcome, because it can wet insulation, bypass the weather barrier and damage linings long after the test is finished. Concealed paths should be investigated with the same seriousness as visible ones, using inspection openings, borescopes or a controlled strip-back where the mock-up allows it. The mock-up is the right place to make those openings, because the effort of discovery is modest and the lesson is transferable.

The third category is drainage behaviour. Water may enter the track or sill as designed and then fail to leave. Observers should watch the weep paths, the sill, the head, the jambs and any pressure-equalisation chamber. Standing water, overflow at the wrong point, staining, debris accumulation and slow clearing are all observations worth recording, even if no water reaches the interior. A window that drains slowly in a mock-up will drain more slowly when it is dirty, when the wind is blowing from another direction, or when the building has settled.

The fourth category is the behaviour of the surrounding construction. Water may appear at the wall junction, at the membrane lap, at the flashing termination or at the internal lining, which points to the interface rather than the window. The observer should not stop at the first wet patch. The path should be traced back to its origin, and the origin should be photographed and described in relation to the assembly, not just in relation to the room.

Testing discipline matters as much as the observations. The same observer should watch the same locations through the whole sequence, under the same lighting, at the same intervals. Photographs should be taken with a location reference and a note of the test stage, because a close-up of a wet corner is useless six months later if nobody knows which corner it was. The test record should distinguish between water that appeared during the test, water that appeared after release, and water that was found later during a strip-back. Those are different findings with different causes. The knowledge base figure of up to 960 Pa under AS 4284 is a reminder that high-performance systems are tested well beyond ordinary service conditions, but the observation record, not the headline number, is what tells the project whether its own assembly is sound.

Air Observations During the Mock-Up

Air testing is sometimes treated as a secondary concern on window projects, particularly in mild climates. That is a mistake. Air leakage carries moisture, undermines acoustic separation, increases heat loss and gain, and often follows the same path that water will take when the weather turns. A window that leaks air at a joint is telling the project that the joint is not continuous, and a joint that is not continuous is unlikely to be weathertight under pressure.

The usual leak paths are predictable. They occur at the frame-to-wall junction, at corners of the frame, at the meeting stiles of sliding and stacking units, at hardware penetrations, at the sill and track assembly, at mullion and transom junctions, and at any place where a gasket is spliced, stretched or interrupted. Glass itself is rarely the problem. The problem is the network of joints around it.

Observations should be qualitative as well as quantitative. A smoke pencil, a hand, a thin tissue or a thermal pattern can reveal the direction and location of a leak even when the overall test result is acceptable. Whistling, dust tracking, curtain movement and condensation on a cold day are all clues that a path exists. The observer should record the location and the apparent direction of flow, then investigate the detail that produced it. A leak found at low pressure may be masked at high pressure by the deflection of a gasket or the movement of a sash, so the test sequence should include a check at more than one stage where the procedure allows it.

The air test is also a check on the installation, not just the window. Gaps between the frame and the wall, missing backer rod, incomplete sealant, unsealed penetrations for fixings and services, and discontinuities in the air barrier all show up as air paths. These are the same details that determine whether the facade performs acoustically and thermally. Recording them in the mock-up allows the project to correct the detail before it is repeated, and it gives the installer a clear picture of what a continuous seal actually looks like.

Interfaces: The Joint Between Window and Wall

The window-to-wall interface is the most consequential detail in the whole assembly. It is also the detail most likely to be designed by one party, installed by another and inspected by nobody. A mock-up should treat the interface as a first-class subject, not as the place where the window ends and somebody else’s problem begins.

The interface includes the substrate, the fixing, the packing and shims, the weather barrier, the air barrier, the flashing, the sealant, the backer rod, the internal lining and the finishes. Each of these has a function, and each can compromise the others. A shim that is too tight can distort the frame. A fixing that penetrates the weather barrier without a seal creates a path. A flashing that is lapped the wrong way directs water into the wall. A sealant that is applied before the membrane is complete traps moisture behind it. A lining that is fixed before the seal is inspected hides the evidence.

Sequence is therefore part of the design. The mock-up should demonstrate the intended order of work and prove that each trade can access its part of the detail without damaging the work of the trade before it. In many projects the correct order is roughly: prepare the opening and substrate, install the weather barrier and flashing, set the frame and fixings, complete the air seal and the interface seal, then install the internal lining and finishes. The exact order depends on the wall type and the system, but the principle is constant: the sealing and flashing must be complete and inspectable before they are covered.

Movement also belongs at the interface. Buildings move, substrates shrink and creep, and aluminium expands and contracts differently from masonry, concrete or timber. The seal at the interface must be designed to accommodate that movement without tearing or losing adhesion. A rigid, heavily filled sealant in a joint that needs to move will crack. A soft sealant in a joint that needs support will sag. The mock-up is the place to see how the chosen seal behaves when the joint is built at realistic tolerances rather than at drawing-perfect dimensions.

Dissimilar materials need attention as well. Aluminium in contact with other metals can corrode, and fixings must be compatible with the frame and the substrate. The mock-up should confirm the fixing type, the isolation detail and the drainage path around the fixing. It should also confirm that the interface can be inspected and maintained after handover, because a seal that cannot be reached cannot be repaired.

Seals and Gaskets

Seals are the most heavily loaded and least visible part of a window. They are expected to keep out water, control air, reduce noise and accommodate movement, often while being compressed, stretched, painted, cleaned and exposed to sun. The mock-up should inspect every seal line as a deliberate exercise, with a marked-up drawing and a checklist, rather than relying on a general impression that the window looks well made.

Gaskets should be continuous around each perimeter, with corners formed or joined in a way that maintains compression. A splice on a flat face is more vulnerable than a moulded corner, and a gasket that is stretched during installation will pull back and leave a gap. The mock-up should confirm that the gasket is the correct profile for the groove, that it is seated fully, that it is not twisted, and that it compresses against the frame or sash as designed. Lubricants and cleaning agents should be compatible with the gasket material, because some products cause swelling or hardening that only appears months later.

Sealants should be treated as engineered joints, not as gap filler. The joint should have the correct width and depth, a backer rod where required, a primer if the substrate needs one, and a tooled profile that ensures adhesion to the correct faces. The mock-up should include an adhesion check, either a peel test on a sample or a careful inspection of the cured bead, and it should confirm compatibility with the membrane, the frame finish and the surrounding materials. Sealant applied over dust, moisture or release agent is a latent defect, even if it looks neat on the day.

The most common seal defects are worth naming because they recur on almost every project. The gasket is compressed at the middle of a sash but not at the corners. The sealant bead is continuous on the outside but the backing rod is missing, so the joint is too shallow. The membrane is terminated behind the frame but not sealed to it. The fixing is sealed at the head but not at the shank. The weep slot is bridged by sealant intended to make the detail look tidy. The internal lining is installed before the seal is inspected. Each of these can be found in a mock-up if someone is looking for them, and each can be prevented if the finding is written down and acted on.

Drainage and Pressure Equalisation

An aluminium window is not a sealed box. It is a drained system. Water that passes the outer line of defence is expected to enter a controlled cavity, lose its energy, and leave through a designed path without reaching the interior. That principle is easy to state and easy to defeat in construction, because the drainage path is small, hidden and easily blocked.

The mock-up should confirm that the drainage path exists from the highest point where water can enter to the lowest point where it can leave. That includes the track or sill, the corners, the mullion and transom junctions, the head, and any chamber that is intended to equalise pressure. Weep slots and baffles should be open, correctly oriented and not obstructed by sealant, gaskets, debris or the frame fixing. The sill should fall in the right direction, and the outlet should be clear of the wall, cladding or flashing that might dam it.

Pressure equalisation depends on compartmentation. If a cavity is intended to equalise with the outside, it must be vented and baffled as designed, and it must not be accidentally connected to the interior or to another cavity. Sealant that bridges a baffle, a gasket that blocks a vent, or a fixing that penetrates a compartment can all change the way the system behaves. The mock-up should include a water application that is heavy enough to reach the drainage path, followed by an inspection of the cavities and the outlets. Observers should note how quickly water clears, where it stains, and whether any water remains trapped after the test.

Drainage also has a maintenance dimension. A path that works when new may not work when it is loaded with dust, pollen, insects or construction debris. The mock-up should confirm that the outlets can be reached and cleaned, and that the detail does not rely on a narrow slot that will close up over time. If the design includes a removable bead or a accessible sill, the mock-up should prove that it can be removed and reinstated without damaging the seals.

Glazing in the Mock-Up

Glazing is part of the window assembly, not a separate purchase. The mock-up should use the production glazing make-up, the production edge treatment and the production setting details, because a substitute pane proves nothing about the assembly that will be installed. AS 1288 provides the framework for glass selection and installation, while AS 2208 addresses safety glazing where it is required. The mock-up should confirm that both have been applied to the actual location, not just to a typical bay.

Setting blocks and edge clearance are small details with large consequences. The glass must be supported at the correct points, with clearance from the frame and from hard contact that could initiate a crack. The blocks must not block the drainage path, and they must be positioned so that the pane’s weight is transferred to the frame rather than to the bead. The mock-up should show the blocks in place before the bead or gasket is installed, and it should record their position so that the installer can repeat it.

The glazing system should be checked for drainage and ventilation. A drained and ventilated system needs open paths at the correct locations, and those paths must not be sealed by a well-meaning applicator. The edge seal of an insulating glass unit must be protected from contact with incompatible sealants, solvents or cleaning agents. The bead or gasket should compress the pane evenly without distorting the frame or leaving a gap at a corner. Where safety glazing is required, the marking and the installation should be checked against the location, not assumed from a schedule.

Handling damage is another mock-up observation. Chipped edges, scratches, sealant smears and contamination may not affect the immediate test, but they affect durability and appearance. The mock-up should establish the standard for protection, cleaning and touch-up, and it should identify the point at which a damaged unit must be replaced rather than repaired. That standard can then be applied to every subsequent opening.

Installation Records

An installation record is not a pile of photographs taken at the end of the job. It is a contemporaneous account of what was installed, where, by whom, with what materials, under what conditions, and with what verification. The mock-up is the best place to design that record, because it is small enough to manage and important enough to justify the effort.

A useful record set includes the approved shop drawings and the revision that was actually built, the installation method statement, the inspection and test plan with its hold points, the product identification and batch details, the fixing type and location, the packing and shim arrangement, the sealant and gasket details, the substrate condition, the weather at the time of installation, the personnel and their competence, and the signed-off inspection sheets. Photographs should be indexed to a location and a stage, not simply stored by date. A photograph of a sealed joint is only useful if it shows which joint, at which stage, before or after the lining.

The record should also capture deviations. If a fixing had to move, a shim had to be added, a sealant had to be changed or a detail had to be varied, that should be documented and approved rather than absorbed silently into the work. Deviations are the raw material of future defects, and a record that hides them is worse than no record at all, because it creates false confidence. The mock-up sign-off should attach the defect list and its resolution, so that the benchmark is a complete package rather than a set of good-looking photographs.

At handover, the installation records should link the mock-up to the installed work. A building owner or facility manager who can trace a window back to its installation record, its test evidence and its maintenance requirements is in a much stronger position than one who receives only a warranty document. The record is also the basis for any later investigation, because it shows what was intended and what was actually done.

Defect Closure

A defect that is observed but not closed is a defect that will be repeated. The mock-up should establish a defect register with a unique identifier, a precise location, a description, an assessed cause, a responsibility, a proposed corrective action, a re-test requirement and a close-out date. The register should be reviewed at the end of each mock-up stage, not at the end of the project, so that the lessons are applied while the work is still mobile.

Root cause deserves more attention than symptom. Water at the internal sill may be caused by a missing end dam, a blocked weep slot, a membrane lap that runs the wrong way, a sealant bridge or a gap at the frame corner. Treating the wet patch with more sealant may hide the symptom and make the next test pass, while leaving the path in place. The register should record the investigation, not just the repair, and the repair should be verified by the same method that found the defect.

Re-test scope should be agreed before the test, not negotiated after a failure. A local repair may be sufficient for a local defect, but a defect that arises from a systemic detail may require a repeat of the full sequence or a check of every similar location on the building. The project should also consider whether the same detail appears in other wall types, other orientations or other window configurations, because a mock-up covers only a sample of the building.

Trend review turns a defect register into a management tool. If the same issue appears once, it is a defect. If it appears repeatedly, it is a process problem, and the process needs to change: the detail, the training, the supervision, the sequencing or the inspection criteria. Closing individual defects without changing the process guarantees that the next building will have the same problems. Closing the process is what makes the mock-up worthwhile.

A Practical Checklist for the Mock-Up

Confirm the applicable edition of the National Construction Code and the project’s evidence requirements before the mock-up is built.
Write the boundary statement: specimen, wall build-up, interfaces, tests, acceptance criteria and exclusions.
Confirm that the tested product configuration, size and glazing make-up match what is proposed for the project.
Build the mock-up with the production team, the production materials and the production sequence.
Include the real weather barrier, air barrier, flashing, membrane, sealant and internal lining at the interface.
Inspect and photograph every seal line before it is covered, with a marked-up drawing as the checklist.
Check gasket continuity, corner compression, splice position and compatibility with lubricants and finishes.
Check sealant joint design, backer rod, primer, adhesion, tooling and compatibility with adjacent materials.
Confirm that weep slots, baffles, vents and drainage paths are open and will remain accessible for cleaning.
Confirm glass support, setting block position, edge clearance, bead compression and protection of the unit edge seal.
Run the water and air observations with a consistent observer, lighting and stage-by-stage recording.
Record concealed paths as carefully as visible leaks, using inspection openings where necessary.
Record the installation: fixings, packers, sealant batches, substrate condition, weather, personnel and hold points.
Review the defect register at the end of each stage and agree the re-test scope before remedial work starts.
Sign off the mock-up as a benchmark, with its records and its closed defects, before production is released.

Frequently Asked Questions

Is a project mock-up the same as a type test?

No. A type test evaluates a product specimen under controlled conditions and supports a performance claim for that specimen. A project mock-up evaluates the project’s assembly, interfaces and workmanship. The two are complementary: the type test provides the performance evidence, and the mock-up demonstrates that the project can build to it. A mock-up cannot replace a type test, and a type test cannot replace a mock-up.

Does a mock-up have to include water and air testing?

Not necessarily. The scope depends on the project’s risks, the stage of design and the evidence already available. A visual and installation mock-up may be sufficient where the system is well established and the interfaces are simple. A performance mock-up with water and air observations is appropriate where the facade is complex, the weather exposure is severe, the wall build-up is unusual or the project needs to verify a critical detail. The important point is that the scope is stated in advance and the results are not used beyond it.

Should the mock-up be built on site or in a laboratory?

Both have a role. A laboratory mock-up gives controlled conditions and can be instrumented more easily, but it may not reproduce the real wall, the real access or the real trades. An on-site mock-up reproduces the actual construction and the actual sequence, but it is exposed to weather and site conditions. Many projects benefit from a laboratory test for performance and an on-site mock-up for installation quality. Where only one is possible, the choice should follow the question the project most needs answered.

How long should the mock-up remain in place?

The mock-up should remain until the benchmark has been inspected, the defects have been closed and the installation team has been briefed. On some projects it is retained as a permanent reference and may even become part of the building. On others it is removed after sign-off. The decision should be made at the planning stage, because it affects the location, the weather protection and the sequence of the surrounding work.

What if the mock-up passes but the installed windows leak?

A mock-up is a sample, not a guarantee. If the installed work leaks, the first question is whether it matches the mock-up in materials, sequence and detail. The second is whether the mock-up itself was representative of the location that is leaking. Records are essential here, because they allow the project to compare what was built with what was tested. A leak that cannot be explained by a deviation suggests that the mock-up boundary was too narrow or that the test did not reproduce the service conditions.

Do New Zealand projects follow the same rules?

No. New Zealand has its own framework, including SNZ TS 4211:2022 for window performance and SNZ 4223 for glazing, together with the building consent process and the relevant New Zealand building code requirements. Australian test evidence and Australian installation practice should not be assumed to satisfy a New Zealand project. The mock-up should be planned around the New Zealand specification, the local climate and the consenting pathway, with evidence that matches the actual installation.

Can the mock-up be used as a workmanship benchmark?

Yes, and that is one of its most valuable functions. Once the mock-up has been inspected and accepted, it becomes the physical standard against which subsequent installations can be compared. For that to work, the mock-up must be accessible, photographed in detail and documented with the same records that will be required on site. A benchmark that exists only in a closed file is not a benchmark.

Does a high water test figure, such as up to 960 Pa under AS 4284, guarantee a leak-free building?

No. A high test figure shows what a specific specimen achieved under a specific test. It does not guarantee that every installed window will perform at that level, because installation, interfaces, drainage, seals and workmanship all affect the outcome. The figure is useful for comparing products and for understanding the capability of a system, but the building’s performance is proved by the mock-up, the installation records and the inspection regime, not by the headline number alone.

Conclusion

Aluminium window mock-ups are a quality assurance tool, not a ceremonial one. They exist to test the assembly that will actually be built, at the interfaces where failures actually occur, with the trades who will actually do the work. A mock-up that is planned with a clear boundary, observed with discipline, recorded in detail and closed out through a live defect register will repay the effort many times over, because it turns unknown details into known ones before they are repeated across a building.

The standards framework gives the project a common language: the National Construction Code and the ABCB for compliance, AS 2047 and AS 4284 for product performance, AS 1288 and AS 2208 for glazing, AS 4666 for installation, and SNZ TS 4211:2022 and SNZ 4223 for New Zealand projects. Within that framework, the mock-up is where water, air, interfaces, seals, drainage, glazing and installation records meet. The observations made there, and the defects closed there, are what turn a specification into a facade that performs.