Glazing at the BBC Broadcasting House

MERO-SCHMIDLIN (UK) PLC have worked extensively with the architects, consulting engineers and main contractors at the new extension to BBC Broadcasting House in Portland Place. The Camberley based Bespoke Envelope Contractors have a very extensive back catalogue of prestigious projects throughout the UK and are delighted to add this very contemporary project to their portfolio.

Whilst the terrorist atrocities of The Baltic Exchange (1992) Bishopsgate (1993) and Canary Wharf (1996) may well be long forgotten the damage to the buildings and in many cases by the buildings, left its mark on construction design. As in the more recent Oklahoma Bombing in the USA 90% of all injuries were caused by flying glass. The selection and application of blast resistant glass needs specialist advice and all public buildings now have to take this element into account at design stage. Like most threats it can be hard to determine the size of the explosion and the proximity to your location. The channelling effect of other buildings and street architecture can change the way the pressure wave affects buildings. Post examination of explosions can reveal some odd results. Unprotected buildings further away can sometimes have more damage than more immediate buildings. Although there is a pressure wave the result is glass being pulled out of buildings rather than being pushed in. Once the initial pressure wave of air has hit the building there is a vacuum left where the air has been violently moved out of position. It is the suction effect that can pull the glass outwards.

With this in mind MERO-SCHMIDLIN were tasked with designing and supplying glazing and fixtures that would hold the glass in place and withstand a whole range elements. With the glass facade suspended seven storeys above the ground, the installation was always going to be complex. In some areas there are walkways between the outer building stonework and the glass facade to allow for maintenance. The ‘Horseshoe’ design of the building can also cause a vortex with high winds especially at high level so all of the bespoke stainless steel brackets had to be designed with that in mind in addition to the bomb proof requirements.

The glass is a mixture of acid etched and screen printed and is a very prominent feature of the design. The facade also featured precision cut Portland Stone panels to match the existing structure. With CAD computer and Robotic cutting techniques, natural stone can now be engineered to achieve incredibly slim profiles. Whilst the use of natural stone may have its detractors with regards to sustainability, these methods enable a block of stone to be cut so thin it can now be used as a rainscreen cladding rather than a supportive block. As such far less stone is required and it can now become a lightweight long lasting alternative to aluminium, steel or composite cladding.

MERO-SCHMIDLIN worked alongside Bruce Briggs who was one of the leading project architects and Neesha Gopal of Ramboll Whitby Bird who were the facade consulting engineers. Both of these very experienced specialists were very complimentary about their experience working with MERO-SCHMIDLIN.

Lord Patten, Chairman of the BBC Trust, said of the new building:

“It provides us with a building which brings together the heart and soul of the BBC and its journalism in one place for the first time; and whose benefits we hope will be reflected in great output for audiences in years to come.”

Neesha Gopal of Ramboll Whitby Bird (Facade Consultanting Engineers) said:

“The installation was very tricky hanging the glazing element seven storeys off the ground to an existing structure. There were issues with a cantilever bracket which Mero-Schmidlin overcame using the workshop facilities we had available to them on site. Mero-Schmidlin site and design teams were very pro-active throughout the whole process and this is an ethos not shared by all the facade contractors we are involved with. What Mero-Schmidlin brought to the table was that if they had any issues they would come to us first rather than create any complications. This enabled the whole installation process to run very smoothly.”

The glazing and facade is very complex even without allowing for the challenges of British weather or terrorist activities. Constructed from flat stainless steel sandwich sections, the outer skin meets the architectural intent of square, straight lines, and flush connections, and is suspended just over a metre from the inner façade. Fixed to this structure is a mixture of clear and opaque point fixed glass panes with flush silicone joints that aims to replicate the visual appearance of the Portland stone. The inner skin is constructed from a modified Schuco curtain walling system with laminated double glazed units for security enhancement, whilst in certain locations a maintenance walkway passes between the two skins. A huge amount of steel framing was used alongside Stainless Steel fixings and fittings. It is to the great credit of everyone involved with the design and installation that very little of the structural framework can be seen from ground level.

The glazing wasn’t just restricted to the exterior of the building. Inside MERO- SCHMIDLIN provided full height glazed screens at almost 4m high to the restored art deco reception area. These screens featured virtually no visible supporting steelwork, and bronze patented brackets and fixings where visible. To the lower levels of the facades, MERO-SCHMIDLIN provided three glazed stainless steel canopies. These canopies cantilever out from the Portland Stone clad walls, supporting laminated glazing panels that are point fixed from above. These canopies were fabricated in one piece off site and lifted into position, to provide minimal disruption to the busy site.

Bruce Briggs one of the projects architects also found the relationship very pro-active when asked What did MERO-SCHMIDLIN bring to the table that impressed him, either on-site or pre-site? he replied:

“For me it’s about two main things. First is the ability to deliver top drawer products, second is the people. The finished product looked like my drawings(at least in my mind’s eye); every element was well manufactured and beautifully assembled. The team was very personable and easy to work with.”

Mike Hart, Operations Manager, MERO-SCHMIDLIN (UK) PLC said:

“Having to engineer and manufacture two very subtly different variations of a cantilevered, suspended, twin walled, blast enhanced, facade and accurately embrace the architectural intent was indeed a challenge. To then install both facade types onto an iconic Heritage structure which continued to broadcast live radio programmes to the rest of the world throughout the site installation period made it even more difficult. Achieving all of this and still receive such praise for our technical input and quality as we have from both the Architects and Facade Consultants makes me proud of the whole Mero-Schmidlin team.”

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