# Facade Mock-Up Testing: The Gate Before Production

> A facade mock-up is a full-size sample of the actual system — real profiles, real glass, real seals — built and tested before the facade goes into production, so that appearance and performance are proven on a few square metres rather than discovered across the whole building.

## Why it matters on a facade project

A facade is the one package where the cost of being wrong scales with the whole
building. An error in a shop drawing does not appear once — it appears in every
panel, and by the time it is visible the panels are installed at height on a
sealed elevation.

The mock-up exists to move that discovery forward, onto a few square metres, at
a point where changing the answer is still cheap.

## What gets tested, in order

| Stage | Test | What it proves |
| --- | --- | --- |
| 1 | Visual approval | Colour, tint, joint width, spandrel-to-vision match in daylight |
| 2 | Air infiltration — ASTM E283 | Leakage rate at design pressure |
| 3 | Static water — ASTM E331 | No penetration under sustained spray and pressure |
| 4 | Dynamic water — AAMA 501.1 | Performance under wind-driven rain |
| 5 | Structural loading | Deflection under positive and negative design pressure |
| 6 | Re-test after structural | Seals still perform after the frame has flexed |

The final step is the one most often dropped, and the most revealing. A facade
that passes water testing before structural loading, then fails after it, is
telling you the seals cannot survive the movement the building will actually put
them through.

## Common mistakes

- **Building the mock-up from different components.** A mock-up assembled with
  substituted gaskets or a different sealant proves nothing about what will be
  installed.
- **Treating it as a formality after production has started.** If the factory is
  already running, the mock-up has no authority and is only theatre.
- **Approving colour under artificial light.** Vision and spandrel glass read
  differently in daylight, at angle, with a lit interior behind one and a dark
  cavity behind the other.
- **Skipping the post-structural water re-test.** Movement is what opens seals.
- **Testing at the wrong pressure.** Test pressure derives from the design wind
  pressure for that building under IS 875 Part 3, not from a standard default.

## How Hagerstone approaches it

Facade work runs through 79+ quality checkpoints and in-process inspection with
sign-off before despatch, backed by ISO 9001, ISO 14001 and ISO 45001
certification. With fabrication in-house, a mock-up finding feeds straight back
into the production line rather than through a supply chain.

## Standards referenced

Air leakage is measured to **ASTM E283**, static water penetration to **ASTM
E331**, and dynamic water penetration to **AAMA 501.1**. Test pressures derive
from the design wind pressure established under **IS 875 (Part 3)**.

## Frequently asked questions

### What is the difference between a visual and a performance mock-up?

A visual mock-up is built on or near site to approve appearance — glass tint, panel colour match, joint width, how the spandrel reads against the vision glass in real daylight. A performance mock-up goes to a test laboratory or rig and is subjected to air, water and structural loading. Larger projects need both; they answer entirely different questions.

### When should the mock-up be signed off?

Before production release, without exception. Once the factory starts cutting profiles and ordering glass, a change means re-tooling and re-ordering. The mock-up is only worth building if it is genuinely allowed to stop production.

### Is a mock-up needed on a small facade?

A full performance mock-up is hard to justify on a small job. A visual mock-up almost always is — colour matching between vision glass and spandrel, and joint appearance, cannot be judged from samples in an office. Even a single bay built on site catches problems that would otherwise repeat across the elevation.

## Sources

- [ASTM E283](https://www.astm.org/products-services/standards-and-publications.html) — Air leakage through exterior windows and curtain walls
- [ASTM E331](https://www.astm.org/products-services/standards-and-publications.html) — Water penetration under static pressure
- [AAMA 501.1](https://fgiaonline.org/) — Dynamic water penetration

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Source: https://hagerstone.com/glossary/facade-mock-up-testing