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Preserving buildings of national importance with Selectaglaze secondary glazing

Countless Government properties, such as Assembly buildings, Town halls, Courts and central Parliament buildings have a historical context which demands to be protected. However, these buildings must also make sure that they are equipped for changing needs. Secondary glazing can form a key part of the strategy for coping with these altering conditions.

The conservation of these prominent buildings depends on sensitive adaptations. Many are Listed with architectural designs that include opulent windows often of colossal size. Selectaglaze secondary glazing, with its broad range, delivers considerate and bespoke treatments that help reach top environmental standards and, as a reversible adaptation, fulfil the obligations of heritage bodies.

Government buildings face a real and credible threat to their security and windows are a particularly vulnerable element. Selectaglaze secondary glazing is designed and tested to provide high level blast mitigation and intruder protection equivalent to that offered by heavy bars and grilles. These treatments are discreet and provide a normalised environment for occupants without highlighting the protection to outsiders. 

National and Local Governments must play an important role in driving a sustainable recovery.  For substantial building works, Government Buying Standards need an approved environmental assessment and when BREEAM is used, a minimum rating of ‘Very Good’ must be achieved. Selectaglaze secondary glazing can support with certification through increased thermal performance of the windows, better wellbeing, especially through acoustic improvements and product sustainability. 

Reading Town Hall

Reading Town Hall’s Wedding Ceremony Room, in the Grade II* part of the building required better acoustic insulation on seven of the primary windows, to ensure minimal breakthrough of outside noise during wedding registries. As the building is Listed, secondary glazing was chosen as a way of dealing with mitigating noise from the busy thoroughfare.

23 units were installed to 7 enormous original windows in the Ceremonies Room. The very large Gothic arched primary windows were just over 4 metres high, so had to be treated with a combination of units to ensure the perfect acoustic insulation. Each opening was treated a combination of three or four transom coupled secondary glazed units with a Series 42 curved fixed light system affixed at the top. The slimline Series 10 horizontal sliding units specified for the lower units on the wider windows, whereas the Series 45 side hung casement was selected for the narrower windows. This ensured that sightlines from the primary windows were not compromised irrespective of the differing widths of the primary windows. 6.4mm acoustic laminate glass was specified for each and a cavity of 100mm from the original windows ensured that secondary glazing units reduced noise levels by between 40-45dB. In most instances this achieves World Health Organization guidelines for quiet environments. An additional benefit of this treatment was that the thermal controls were also enhanced, making the room warmer.

Braintree Town Hall

Braintree Town Hall was faced with the challenge of making its building more energy efficient, which was no easy task seeing as it is Grade II* Listed. One area in particular needed attention – the windows, which allowed cold air in and heat to escape. The original specification was to install timber secondary glazing to fit in with the wood panelled rooms. This was more challenging than initially realised but Selectaglaze secondary glazing specialists had an alternative solution to propose. Selectaglaze produced a sample using aluminium secondary glazing with a timber grain finish. A meeting was arranged with Braintree Town Hall and the local Conservation Officer and on the day, the aluminium sample was set up next to one of the windows. Initially the Conservation Officer was sceptical of using aluminium secondary glazing until attention was drawn to the sample placed next to the window.

After the successful demonstration, Selectaglaze went on to install a total of 20 vertical sliding units using a mixture of the Series 20, which is a slim frame ideal for heritage buildings and the mid-range Series 25 which is the perfect option for larger windows, as it can take heavier glass while still being an unobtrusive adaptation. All products were finished with a timber grain effect that harmonised perfectly with the interior.

Founded in 1966, Royal Warrant Holder Selectaglaze has considerable experience of working within Listed and sensitive buildings.

For further details, visit:, T: 01727837271, E:

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