1960’s office building transformed into luxury apartments

Image: © Nic Grant, Lindner Group

The Rotunda is the last part of the re-development of the land mark Bullring in central Birmingham. The well-known, 21 floor, listed, 1960’s office building was modernised into luxury apartments without interfering with Birmingham’s busy main shopping district by using pre-fabricated cladding elements set up from a roof mounted crane.

Unitised curtain wall facade.
The entire re-cladding operation was attained without scaffolding by using a pre-fabricated and pre-glazed unitised form of construction. The bespoke curtain wall elements 2.85m wide by 3.2m high were manufactured in our headquarters in Arnstorf. The elements were then installed using a roof mounted crane and lifting chimney.

Facade types and scope

Design, manufacture and installation of bespoke cladding systems including:

• 5,700 m2 fully unitised storey height elements with concealed sliding doors
• 500 m2 ventilated textured glass rainscreen to concrete walls
• 200 m2 plantroom louvers
• External structural glass balustrades
• Internal glass balustrades
• Copings, soffits, cills
• Doors

Facade technical details. Facade performance – tested to CWCT sequence B

• Air permeability: 600 Pa
• Watertightness static and dynamic test: 600 Pa
• Wind resistance service: +1850 Pa / -2100 Pa
• Wind resistance safety: +2775 Pa / -3150 Pa
• Thermal insulation curtain wall: Ucw 1.7 W/m2K
• Thermal insulation glazing: Ug 1.4 W/m2K
• Solar shading / glazing g value: 0.36
• Light transmission: 65%

Unitised Main Facade to Apartments

The main envelope comprises 36 faceted elements per floor to suit the circular floor plate of the tower. Each element contains a fixed pane and a “pop-in” type sliding door. The doors are specially designed to travel across a 5 degree facet angle, and can provide “crack ventilation” in their tilt position, or open fully to provide a stunning vista across the city.

Image: © Nic Grant, Lindner Group

The doors are structural silicon glazed and the fixed panes are capped and retained by gaskets. This gives uniform external appearance to the fixed and opening panes. The system achieves air permeability and watertightness of 600Pa according to CWCT sequence B.

Internal glazed balustrades provide protection when the doors are open. Double glazed units to the vision glazing have a combined high performance solar control and low-e coating to give excellent thermal insulation yet prevent solar overheating. Single glazed spandrels of textured and fritted glass add character and sparkle at the slab zone. The spandrels also conceal the ventilation inlets and outlets for bathrooms and kitchens positioned behind the glass.

Special separators installed between the curtain wall mullions and the internal walls provide exceptional levels of acoustic flanking insulation and fire separation between apartments. Fritted textured glass is also used as a rain-screen to the concrete walls at the interface to the podium building. Aluminium profiles have a natural anodised finish.

For more information visit www.Lindner-Group.com

Developer: Urban Splash
Main Contractor: Urban Splash
Architects: Glenn Howells Architects
Completion date: 2008