# Facade Rain-Screen Ventilated Systems

> A rainscreen, or ventilated facade, is a cladding assembly whose outer panel is a screen rather than a waterproof skin: a drained, ventilated cavity behind it carries away water that gets past, and the breather membrane on the backing wall is the actual weather line. Cavity barriers at every compartment line control fire spread through the continuous cavity.

## What we deliver

**Imported ventilated envelope systems** — the sub-frame, insulation, breather
membrane, cavity barriers and outer panel installed as one designed assembly.

The system works on a principle that surprises people the first time they hear
it: the outer skin is not waterproof and is not meant to be. It is a screen. The
drained, ventilated cavity behind it is what manages the water that gets past.

## Facade leadership experience

Our Director – Facade, Akhilesh Kumar Singh (25+ years in facade engineering),
has led delivery on projects including:

| Project | Location | Scope | Quantity |
| --- | --- | --- | --- |
| DLF — WeWork | Cyber City, Gurgaon | Kingspan dry cladding ventilated system | 3,325 sq. m. |

## The assembly, outside in

| Layer | Function |
| --- | --- |
| Outer panel | Sheds rain, handles UV, sets appearance |
| Cavity, 25-50mm | Drains and ventilates; open at bottom and top |
| Cavity barrier | Stops fire and smoke at every compartment line |
| Insulation | Thermal performance; mineral wool preferred |
| Breather membrane | The actual weather line — continuous and lapped |
| Sub-frame | Carries panel load to structure; thermally broken |
| Substrate | RCC, blockwork or sheathing board |

## What drives the cost

Panel material — ACP, solid aluminium, HPL, terracotta, stone · cavity depth ·
extent of cavity barriers · insulation grade and thickness to meet ECBC ·
sub-frame complexity and bracket spacing · whether brackets are thermally broken
· building height and access strategy.

## Where projects go wrong

- **Cavity barriers omitted or shortcut.** The most serious failure mode
  available in this system.
- **Membrane treated as secondary.** A discontinuity at a corner, penetration or
  lap leaks regardless of panel quality.
- **Ventilation path blocked.** Insulation pushed into the cavity or sealed
  openings stop the airflow, and the cavity stops working.
- **Thermal bridging ignored.** Hundreds of brackets through the insulation can
  undo the assembly U-value the specification was written to achieve.
- **Combustible insulation behind a combustible panel.** Each may pass alone;
  together in a ventilated cavity they are a different proposition.

## Why Hagerstone

**One team detailing the whole assembly.** Sub-frame, membrane, insulation,
barriers and panel are designed together rather than split between a cladding
supplier and a site contractor who meet only at the interface.

**Imported systems** within our in-house facade scope, alongside curtain wall,
fenestration and cladding — so the junctions between systems are one party's
responsibility.

**79+ quality checkpoints**, ISO 9001 / 14001 / 45001, 100% in-house execution.

## Standards referenced

Fire and life safety, including cavity barrier requirements for external wall
assemblies, under **NBC 2016, Part 4**. Opaque assembly U-value under **ECBC
2017**.

## Frequently asked questions

### Why choose ventilated over face-sealed cladding?

Because sealed joints do not survive Indian monsoon conditions indefinitely. Every seal eventually ages, moves or gets damaged, and once water is behind a face-sealed system it has nowhere to go. A rainscreen accepts that some water gets past the outer panel and gives it a drained, ventilated route back out. It also reduces solar heat gain into the wall, because the cavity carries warm air away.

### What actually keeps the building watertight?

The breather membrane on the backing wall, not the panel. The outer skin is a screen — it handles wind-driven rain, UV and appearance. The membrane behind it is the weather line, and it must be continuous, correctly lapped and taped. Most rainscreen failures trace back to the membrane, not the cladding.

### How is fire spread through the cavity controlled?

With cavity barriers at every compartment line and around openings, plus non-combustible insulation and a limited-combustibility panel. The cavity is continuous by design, which makes it a potential chimney. Barriers are not an optional extra — they are what makes the assembly compliant under NBC 2016 Part 4.

## Sources

- [NBC 2016, Part 4](https://www.bis.gov.in/standards/national-building-code/?lang=en) — Fire and life safety
- [ECBC 2017](https://beeindia.gov.in/) — Building envelope — opaque assembly

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Source: https://hagerstone.com/services/facade-glazing/rainscreen-ventilated-systems