Where there are gaps there are flaws and this very true if you want to receive the full benefits of a secondary glazing treatment

Where there are gaps there are flaws; the importance of independent secondary glazing frames


Treat Of The Month


acoustic secondary glazing, arches shapes and curves, fixing methods

The approach to a secondary glazing treatment can be led by different factors: client requirements, budget, make up of the original window/s and their surrounds, as well as ensuring the integrity of the desired benefit. In this project, an old library had fallen into a state of disrepair, so had been earmarked for conservation and refurbishment to spearhead a major regeneration project in Plumstead. The client wished for the building to provide a welcoming and warming community space, hosting events and reverting rooms back to use as a library. As part of the redesign and programme of works to bring this Grade II Listed building up to 21st century standards, the window performance needed to be addressed. Facing directly onto the High Street with heavy traffic flow, noise was an issue. Due to the age of the building, thermal retention was poor and heat was being lost through the windows, despite having very rudimentary secondary glazing. In addition, full access to the primary windows was required for future maintenance, decoration and cleaning, which the existing secondary glazing prevented. Two of the rooms on this façade were allocated for reading rooms which had large sweeping bays with metal framed primary windows. The original secondary glazed sweeping bay window at Plumstead Library, where each unit was independently fixed directly into the stone work The sweeping bay with units stacked flanking each side of the curve The old secondary glazing provided little benefit to enhance the performance of the primary windows and each unit was individually fixed directly into the stone mullions and transoms. The bottom and top row were fixed panes, preventing access to areas of the original glazing, and the centre row made up of opening casements. The fixing method, clamping directly into the stonework with screws and plugs to compress a bubble seal was effective for the flanking units each side, where there was a flat surface. However, in the bay section where the stonework curved, the seals did not touch the stone and therefore negated any benefit. Curved bay where the seal does not clamp the original fabric of its surrounds, which negates the benefits, allowing heat to escape and noise to enter Curved bay where the seal does not clamp the original fabric of its surrounds Where there are gaps there are flaws – gaps will provide a passage for sound and noise to travel, as well as an escape route for heating and inlet for draughts. This is where the importance of a fully independent system comes into play. Following the strip out of the existing secondary glazing and repairs to the primary windows, detailed measurements were taken using a laser 3D modeller, so accurate templates could be made up for the timber frame that the secondary glazing was to be fixed onto. The timber grounds with arched back face, square front and mullions, which provide a fully integrated and independent secondary glazing system to be fixed to
Timber grounds with arched back face, square front and mullions The back face of the timber had to fit exactly to the curvature of the bay and the front surface to be perfectly square to accept the secondary glazing. A deeper than normal timber ground was created, to ensure the glass to glass cavity was sufficient to provide the desired acoustic insulation. Timber mullions were designed into the base timber work, to make the secondary glazing treatment as discreet as possible. Once all the framework was installed, the units could be fixed into place. Due to the height of the bay, over 3m high, and the requirement to provide full access to the primary windows for cleaning and maintenance, the openings were treated with Series 20 slimline vertical sliding units transom coupled to Series 45 slimline side hung casements. The transoms came ready fixed, to ease the speed of installation. Selectaglaze secondary glazing systems with pre fixed mullions, to enable rapid installation on site, onto pre-set timber grounds in a sweeping curved bay at Plumstead Library Series 20 slimline vertical sliding secondary glazing with transoms By installing a totally independent and cohesive system, optimal acoustic and thermal benefits were met. The client's brief was also satisfied, with full access to the primary windows and a discreet unimposing treatment of the beautiful Victorian sweeping bay. The final acoustic insulation and thermal retention secondary glazing treatment by Selectaglaze at Plumstead Library