Insight / Performance Mockup Unit
A PMU is not a test for every building. It is used when the risk needs proving early.
A Performance Mockup Unit (PMU) is a full-scale facade section assembled and tested at an accredited laboratory before production begins. It does not certify an entire building as safe. It gives the project team a chance to find a detail that does not work while the change still belongs in the drawings and the workshop.
What a PMU proves
A PMU has to represent the part of the facade whose risk is being tested. Its programme is set by the project, not by the name PMU.
The detail that will actually be built
The mockup carries the project profile, glass, gaskets, joints, and interfaces as closely as possible. A detail left out of the mockup is not proven simply because the rest of the facade passes.
Air pressure and water penetration
Testing checks whether air and water pass through joints under the pressure set for the project. The criterion follows the building specification and its location, not one number for every building.
Structural behaviour
Panels, anchors, and framing are tested against loads relevant to the design. On some projects, inter-storey movement or other conditions are part of the test sequence too.
The interfaces that are hard to repeat
Corners, unit joints, spandrels, transitions into another surface, and non-repetitive details are why a mockup often needs to represent more than one straight panel.
The point before mass production
The value of a PMU is its timing. If something is wrong, the drawings, fabrication method, or installation sequence can still change before many units are made or installed.
The limit of one test result
A PMU proves one system under one arrangement of details and test conditions. It does not replace fabrication control, installation inspection, or testing on the completed building.
A PMU is not a site inspection
A mockup can pass before production while joints made at height still need checking during installation.
A PMU asks whether the chosen design and details can meet the performance criteria under controlled conditions. Site inspection asks something different: whether the work actually installed follows those details and the same standard of workmanship.
Neither replaces the other. A PMU does not make every joint on the building correct by default, and a check on one area of the building does not replace the chance to resolve a difficult detail before production starts.
When a PMU belongs in the project programme
Make the call from the facade risk, not from a testing list copied from the last project.
A taller building with greater exposure to wind-driven rain carries a larger consequence when a detail is wrong. In that setting, resolving the problem on one mockup is far more controlled than finding it after the facade wraps the building.
New details, interfaces between systems, unusual panel geometry, or demanding performance criteria can also make a PMU worthwhile. A facade that does not call for one, however, should not inherit the cost and programme of a test that gives it no proportional protection.
Decide during design which part represents the largest risk, which criteria it has to meet, and when the results must be ready so production does not run ahead. Our team has experience running PMU tests at accredited laboratories when a project calls for them.
PMU questions
PMU is often described as a standard stage. The more useful question is what the test actually needs to answer.
- What is a Performance Mockup Unit (PMU)?
- A PMU is a full-scale facade section that represents the project design, assembled and tested before production starts. An accredited laboratory tests whether that arrangement of details meets the performance criteria already set for the project.
- Does every curtain wall need a PMU?
- No. The need depends on building height, exposure to rain and wind, the complexity of the details, the chosen system, and the contract criteria. A PMU reduces risk where a project calls for it; it is not an automatic stage that adds value to every building.
- What is usually tested in a PMU?
- The programme can include air leakage, water penetration, and structural behaviour. Inter-storey movement, temperature changes, or other tests belong in it only when the design and project requirements make them relevant.
- When should a PMU be planned?
- While the facade details and performance criteria are being decided, before mass production begins. The programme needs time to build the mockup, run the tests, read the results, and revise details if needed.
- Does passing a PMU guarantee that the completed facade will not leak?
- No. A PMU proves one arrangement of details in controlled test conditions. The building facade still depends on fabrication control, installation, site joints, and inspection while the work is under way.