# Curtain Wall Systems — Unitised, Semi-Unitised and Conventional

> A curtain wall is a glazed building facade built in one of three configurations: unitised, with panels assembled in the factory; conventional stick, assembled piece by piece on site; or semi-unitised, which combines site-erected framing with factory-prepared infill. The choice depends on building height, panel repetition, crane access and programme.

## What we deliver

Curtain wall in all three configurations — **unitised, semi-unitised and
conventional stick** — engineered, fabricated and installed as one accountable
package rather than split between a designer, a fabricator and an installer.

The system choice is made on evidence at survey stage. Building height, panel
repetition, crane availability and programme all point to a different answer,
and the wrong choice is expensive to reverse once brackets are set.

## 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 — Building 8 | Cyber City, Gurgaon | Stick curtain wall glazing, aluminium solid sheet, Galvalume & Shera board cladding | 14,175 sq. m. |
| Broadway Service Apartment | Dwarka Expressway, Sector 83, Gurugram | Curtain wall glazing & aluminium doors and windows | 10,550 sq. m. |
| Anygraphics Factory | Noida, Uttar Pradesh | Semi-unitised structural glazing, PIR panel, rock wool panel | 6,500 sq. m. |

## Scope of works

| Stage | What we deliver |
| --- | --- |
| Survey & assessment | Measured survey, slab edge condition, system recommendation |
| Design & engineering | Wind load analysis to IS 875 Pt 3, shop drawings, bracket design |
| Mock-up & testing | Visual approval, ASTM E283 / E331, structural loading, water re-test |
| Fabrication | In-house cutting, routing, crimping, end milling, in-process inspection |
| Installation | Setting out, bracket fixing, panel erection, sealing |
| Testing & handover | Site water testing, snagging, O&M documentation |

## What drives the cost

Height and access strategy · panel repetition across the elevation · glass
specification (SHGC, U-value, DGU build-up) · framing depth set by wind pressure
· whether the facade is unitised or stick · corner and setting-out complexity ·
programme compression.

## Where projects go wrong

- **System chosen before the survey.** Slab edge tolerance and crane access
  frequently rule out the system that was assumed at concept.
- **Ordering before the mock-up is signed off.** Once production starts, a change
  means re-tooling.
- **Structural glazing bite copied from another project.** Wind pressure is
  building-specific; corner and upper-floor panels need more than the average.
- **Spandrel treated as an afterthought.** The cavity behind runs far hotter than
  the vision area and needs heat-strengthened glass and insulation behind it.

## Why Hagerstone

**100% in-house execution** under a Director — Facade with 25+ years in facade
engineering, structural glazing and high-rise exterior work, supported by a
dedicated 20-member facade team.

**79+ quality checkpoints**, in-process inspection and sign-off before despatch,
under ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certification.

**One accountable partner** — facade coordinated with interiors, MEP, civil and
PEB rather than split across vendors who each blame the other at the interface.

## Standards referenced

Wind loading to **IS 875 (Part 3)**. Air and water performance verified to
**ASTM E283** and **ASTM E331**. Quality management to **ISO 9001:2015**.

## Frequently asked questions

### Which curtain wall system should my project use?

It depends on height, repetition and programme, not on preference. Unitised suits tall or fast-track buildings with repeating panels, because factory assembly removes facade scaffolding and compresses the site programme. Stick suits low-rise and irregular geometry where few panels repeat. Semi-unitised sits between them — primary framing erected on site, infill panels prepared in the factory. We assess this at survey stage rather than defaulting to one system.

### Do you fabricate in-house or subcontract?

In-house. Our facade fabrication runs in an approximately 9,000 sq ft facility with over 10,000 sqm per month capacity, on CNC-grade machinery including a fully automatic double head cutting machine with ±0.1mm servo precision, copy router, corner crimping and end milling. Execution is 100% in-house with a dedicated 20-member facade team.

### How is water tightness proven before installation?

Through mock-up testing before production release — air infiltration to ASTM E283, static water penetration to ASTM E331, then structural loading and a water re-test after the frame has flexed. Test pressures derive from the design wind pressure for that specific building under IS 875 Part 3, not from a default value.

## Sources

- [IS 875 (Part 3)](https://standards.bis.gov.in/website/published-standards/department-wise) — Wind loads on buildings
- [ASTM E283 / E331](https://www.astm.org/products-services/standards-and-publications.html) — Air infiltration and water penetration
- [ISO 9001:2015](https://www.iso.org/standards.html) — Quality management

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Source: https://hagerstone.com/services/facade-glazing/curtain-wall-systems