The challenge posed:
In this Grade II Listed building with beautiful decorative panelling, we were asked to provide secondary glazing primarily to provide noise insulation from the busy site works across the road and to raise thermal performance.
When installing secondary glazing to improve acoustic insulation, it is important to create at least a 100mm glass to glass cavity. Sound is transmitted via the direct vibration of the glass. Therefore, by creating an air gap with decoupled primary and secondary glazing, they act as barriers and reduce resonance. So, how can a cavity be created in the image above?
The building was constructed in 1893 and although a fantastic legacy of architectural detailing of the time, it provided a huge challenge in how it would accept a secondary glazing treatment for noise insulation...however we were not to be deterred.
The window boards had inset grilles allowing the warmth from the hidden working heating system to circulate, although a great deal of the energy was lost through the ill-fitting original primary glazing.
The dilemma; ordinarily we would fix a simple timber sub frame, which takes up any irregularities creating a tight fitting opening for the secondary glazing to be installed to. In this case, due to the need for an air gap, the timber frame and additional glazing would be set crossing the middle of the grille, which would result in some of the heat getting caught in the cavity and defeating part of the required benefit - improved thermal retention.
Fortuitously, the glass in the primary windows was set far back in chunky wooden frames, which went some way to creating the desired cavity. Options were discussed with the client on site, but ultimately it lay in the hands of the Selectaglaze Engineering and Development team to come up with a solution.
A. Standard timber fixing detail B. Bespoke timber fixing detail
Figure A shows the standard timber fixing details with a square sub frame, which can be scribed and tailored to take up any irregularities in the reveal.
Figure B shows the special arrangement designed and created to install the secondary glazing to those areas where there were heating grilles in the window boards. The areas highlighted are:
The resulting treatment - timber grain secondary glazing with full access to the window board heating grille
By using the enlarged stepped timber, the heating grille was avoided and not compromised in any way, yet the all-important cavity created for noise insulation. In addition, the frames were glazed with 6.8mm acoustic laminate glass to ensure the rooms, which are used for meetings and conferences, were as quiet as possible.
On face value, you would never realise/notice the hidden intricacy and bespoke detail, to maximise the benefit of the secondary glazing installation. None of the heat is wasted by getting caught up in the cavity and is pushed out back into the room.
In this Grade II Listed building with beautiful decorative panelling, we were asked to provide secondary glazing primarily to provide noise insulation from the busy site works across the road and to raise thermal performance.
When installing secondary glazing to improve acoustic insulation, it is important to create at least a 100mm glass to glass cavity. Sound is transmitted via the direct vibration of the glass. Therefore, by creating an air gap with decoupled primary and secondary glazing, they act as barriers and reduce resonance. So, how can a cavity be created in the image above?
The building was constructed in 1893 and although a fantastic legacy of architectural detailing of the time, it provided a huge challenge in how it would accept a secondary glazing treatment for noise insulation...however we were not to be deterred.
The window boards had inset grilles allowing the warmth from the hidden working heating system to circulate, although a great deal of the energy was lost through the ill-fitting original primary glazing.
The dilemma; ordinarily we would fix a simple timber sub frame, which takes up any irregularities creating a tight fitting opening for the secondary glazing to be installed to. In this case, due to the need for an air gap, the timber frame and additional glazing would be set crossing the middle of the grille, which would result in some of the heat getting caught in the cavity and defeating part of the required benefit - improved thermal retention.
Fortuitously, the glass in the primary windows was set far back in chunky wooden frames, which went some way to creating the desired cavity. Options were discussed with the client on site, but ultimately it lay in the hands of the Selectaglaze Engineering and Development team to come up with a solution.
A. Standard timber fixing detail B. Bespoke timber fixing detail
Figure A shows the standard timber fixing details with a square sub frame, which can be scribed and tailored to take up any irregularities in the reveal.
Figure B shows the special arrangement designed and created to install the secondary glazing to those areas where there were heating grilles in the window boards. The areas highlighted are:
- the heating grille
- indicates the rebated enlarged timber which was produced to fix up close to the primary window, but then steps out over the top of the grille, creating the cavity and flat square surface for the secondary glazing to be fixed to
- a cover fixing strip was applied to make sure the treatment was as discreet as possible
The resulting treatment - timber grain secondary glazing with full access to the window board heating grille
By using the enlarged stepped timber, the heating grille was avoided and not compromised in any way, yet the all-important cavity created for noise insulation. In addition, the frames were glazed with 6.8mm acoustic laminate glass to ensure the rooms, which are used for meetings and conferences, were as quiet as possible.
On face value, you would never realise/notice the hidden intricacy and bespoke detail, to maximise the benefit of the secondary glazing installation. None of the heat is wasted by getting caught up in the cavity and is pushed out back into the room.
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