Acoustic insulation is more often than not the main reason for installing secondary glazing in offices with single glazed primary windows. Assumptions made, based on years of experience, are that it is generally for windows on façades facing busy thoroughfares with high volume traffic, or those overlooking a construction site. However, to make this assumption with a recent project would have been incorrect, as it was far from the norm…
A building in a busy part of London had offices spread over 3 floors with a different tenant on each. In the middle of the building, an original lightwell had been closed in with a large atrium roof, which floods the building with light. The company on the ground floor approached the owners to see if they could use the footprint of the atrium to extend their office space, however expanding their numbers into this cavernous area raised concerns that noise would penetrate the offices on the other floors above and create a disturbance.
The upper floors had inward opening doors to maximise the flow of natural light into the offices. They each had a glass balustrade, atrium side, to protect people from falling, in line with Building Regulations Part K, should the doors be opened. They rarely were and generally only for cleaning and maintenance. It was felt that despite the doors being double glazed, they would not provide sufficient acoustic insulation.
Casement doors overlooking the atrium requiring secondary glazing for noise insulation
Many options were considered but as the building is Grade II Listed, it was decided that secondary glazing would be the most suitable option. The next thing was to work out the best system to use and how it would be fixed.
The preferred method of installing secondary glazing is to site it internally, within the reveal, with a cavity of at least 150mm to gain good dB reductions. In this case, the existing french doors opened inward, meaning any internal treatment would restrict their operation and any access to them. As the 'outside' was also the 'inside' the secondary glazing could be fitted to atrium side of the doors but there was the balustrade taking up the reveal space and of course, from the atrium, they were no longer at floor level. Further options were considered such as; removing and refitting the balustrade in a new location; modifying the balustrade such that it takes up less reveal space or indeed removing the balustrade altogether and upgrading the secondary glazing to provide guarding as well as the noise reduction. Finally, it was decided to introduce a factory finished joinery subframe fitted to the wall face of the atrium side, into which was fitted a fixed secondary glazing panel.
Architectural drawing showing the detail for the secondary glazing
Selectaglaze was able to supply and install the full treatment. The timber subframe was made and fully finished in the joinery workshop. The series 42 fixed light with 6mm toughened glass was made to fit perfectly within, and the whole assembly was fitted to the face of the masonry wall, atrium side to provide the much needed acoustic insulation.
Full scaffolding was erected in the atrium so that the 14 units could be installed safely. Each of them measured approx 3200mm (h) x 1250mm (w) and weighed 65kg – a considerable weight to fix at height.
This is another example of the versatility of secondary glazing and how it can help overcome thermal, noise and security issues inherent in original glazing’s make up and specification.
Casement doors overlooking the atrium requiring secondary glazing for noise insulation
Many options were considered but as the building is Grade II Listed, it was decided that secondary glazing would be the most suitable option. The next thing was to work out the best system to use and how it would be fixed.
The preferred method of installing secondary glazing is to site it internally, within the reveal, with a cavity of at least 150mm to gain good dB reductions. In this case, the existing french doors opened inward, meaning any internal treatment would restrict their operation and any access to them. As the 'outside' was also the 'inside' the secondary glazing could be fitted to atrium side of the doors but there was the balustrade taking up the reveal space and of course, from the atrium, they were no longer at floor level. Further options were considered such as; removing and refitting the balustrade in a new location; modifying the balustrade such that it takes up less reveal space or indeed removing the balustrade altogether and upgrading the secondary glazing to provide guarding as well as the noise reduction. Finally, it was decided to introduce a factory finished joinery subframe fitted to the wall face of the atrium side, into which was fitted a fixed secondary glazing panel.
Architectural drawing showing the detail for the secondary glazing
Selectaglaze was able to supply and install the full treatment. The timber subframe was made and fully finished in the joinery workshop. The series 42 fixed light with 6mm toughened glass was made to fit perfectly within, and the whole assembly was fitted to the face of the masonry wall, atrium side to provide the much needed acoustic insulation.
Full scaffolding was erected in the atrium so that the 14 units could be installed safely. Each of them measured approx 3200mm (h) x 1250mm (w) and weighed 65kg – a considerable weight to fix at height.
This is another example of the versatility of secondary glazing and how it can help overcome thermal, noise and security issues inherent in original glazing’s make up and specification.