Initially built as a Royal Mail sorting office in Birmingham city centre it was redeveloped in 1998 to become Birmingham’s premier shopping and lifestyle destination. Now known as ‘The Mailbox’, the development is one of the UK’s largest mixed-use buildings incorporating retail, leisure, offices and residential.
Visitors can expect a unique shopping experience, take a break at one of its excellent restaurants or relax in the spa and salon. Mailbox’s operators are keen to continuously modernize and optimise their premises for they decided the building to undergo a redevelopment in 2014 and reopening in spring 2015. Part of the improvement was the installation of a sky-lit glass roof to protect guests from the unpredictable British weather, creating a light filled and open environment. Our partner Spectrum Architectural Glazing was awarded the contract for installing the 80m long x 8m wide dual pitch roof over the shopping centre’s atrium. A key part of this design was that the roof construction had to meet with very strict building and performance criteria: it had to be a thermally insulated system and also in the case of an internal fire, heat/smoke resistant to a constant temperature of 200 degrees for 30 minutes. The ideal system as specified by Solarlux for this project was the SDL Nobiles glass roof system which underwent full smoke and heat testing at the ‘Exova’ test institute.
In order to test the heat resistance under realistic conditions, all the fundamental parts of the final roof construction were erected in original scale for the test. The central roof panel of the test specimen had a 3.55m overhang, the distance between axes was 1.25m and the glazing weighed in at 250kg. An inclusive part of the test criteria was to also consider the possibility of snow loadings on the exposed location of the roof and so for test purposes, sand bags with a total weight of 1000kg were placed on the test roof specimen.
To perform the test, the roof was installed in a furnace of sufficient size and initially heated up to 180°C. The temperature was then reduced to the required 120°C and maintained at a consistent level for 30 minutes. No specific heat protection measures were taken and no special heat-resistant materials were used. Solarlux passed the test with flying colours and the certification is another milestone for the product management.
For The Mailbox the roof construction is a milestone also. Retail Manager David Pardoe explained on their website:” As the final pane of glass was skilfully slotted into place last week, it marked a major stage in the era of the new Mailbox. Gone are the days of our customers valiantly trying to stay dry as they dodge the rain between the canopies; we’ve gone undercover. The roof’s sky-lit design ensures that the Mailbox is still flooded with natural light. The most exciting moment for me was the first morning after the roof was completed, standing in the main area as the sun rose and watching the whole place light up – it was a fantastic way to see the new space.”