99-bishops-gate-from-street-crop

Re-Engineering Fire Compartmentation Compliance At 99 Bishopsgate

Restoring High-Integrity Fire Compartmentation in an Occupied Commercial Tower

Executive Summary

99 Bishopsgate is a high-profile, multi-story commercial asset located in the heart of London’s financial district. As part of a critical life-safety asset management cycle, the building management team required the immediate replacement of an outdated, failed fire curtain barrier that had compromised the building’s fire compartmentation strategy.

Adexon was appointed to manufacture, install and commission a fully certified, high-performance active fire barrier in the place of the failed product from a household name manufacturer. The project demanded strict adherence to regulatory standards (E 120). Adexon successfully deployed its advanced FC1-E120 system, completely restoring the building’s life-safety integrity without disrupting weekday commercial operations.

The Core Challenge Involving Remediation

The project team was confronted with a failed legacy fire curtain system deemed entirely unfit for purpose by fire safety surveyors. Leaving the system unaddressed posed a severe liability, exposing the occupied tower to unchecked structural fire vulnerabilities.

The replacement brief presented three primary engineering and logistical constraints:

  • Rigorous Compliance Scopes: We commissioned this project to maintain fire integrity, preventing the passage of flames for 120 minutes (2 hours).
  • Restricted Site Logistics: The commercial tower remained fully operational and occupied by premium tenants throughout the project timeline. To eliminate acoustic and spatial disruption, all intrusive on-site works were strictly confined to weekend shifts. Vertical transport was restricted exclusively to a standard passenger-weight goods lift, which imposed a physical length limit of 3,000mm on all manufactured components.
  • Complex Structural Integration: Integrating the system into the 30-year-old building required addressing oversized structural openings. We installed a custom multi-barrel, overlapping fire curtain with a side-by-side headbox, measuring 15,939mm wide by 2,815mm high. To accommodate the goods lift’s 3,000mm length limit, the system was manufactured using Adexon’s proprietary overlapping barrel system that is tested and certified to provide the required 2-hours of integrity performance, E120. This meant the individual sections could be transported using the existing goods lift and assembled on site.
The Engineered Solution by Implementing FC1-E120

To overcome the physical span limitations and structural boundary variances, the client’s project team specified a custom-manufactured FC1-E120 Fire Curtain configured as an overlapping, multi-barrel system.

System Design & Structural Architecture

Rather than risking single-axis roller sag over the massive structural opening, Adexon engineered a side-by-side, multi-barrel headbox layout. This configuration allows multiple fabric runs to deploy simultaneously with a precise physical overlap, ensuring an unbroken compartmentation line across non-standard widths.

To bypass the strict 3,000mm material length limit imposed by the building’s goods lift, the entire rigid headbox assembly, roller shafts, and side guides were custom-engineered into sections.

Material Science & Performance Benchmarks

The system was tested and certified to EN 13241:2003+A2:2016 in conjunction with EN 16034:2014, and obtained a fire rating of 120 minutes integrity (E) when tested to EN 1634-1:2014, classified in accordance with EN 13501-2:2016, delivering verified performance data across three critical life-safety metrics:

  • Fire Integrity (E 120): The system maintains total structural fire integrity for a minimum of 120 minutes (2 hours), preventing the passage of localised flame across the compartment boundary.
  • High-Tensile Textile Composition: The active curtain fabric consists of high-performance, dense fibreglass interwoven with a reinforced steel wire mesh core.
Meticulous On-Site Sealing & Mechanical Reliability

For on-demand emergency deployment, the system integrates a Class C self-closing mechanism driven by a heavy-duty, low-voltage 24V tubular motor paired with an internal planetary gearbox. This setup ensures that upon receiving a fire alarm relay trigger or during a total local mains power failure, the curtain drops at a controlled velocity under gravity-failsafe conditions to reliably seal the opening.

The Outcome

By merging precision off-site fabrication with a highly coordinated weekend logistics strategy, Adexon successfully replaced the failed life-safety asset with zero disruption to weekday tenant activities, office access, or corporate operations.

The custom-engineered multi-barrel headbox is fully integrated into the modernised ceiling plane, meeting the high aesthetic expectations of a prime London commercial asset while exceeding the required local building safety compliance codes. Full fire and life-safety assurance have been completely restored to 99 Bishopsgate.