Why Secondary Glazing? Detail & Event

Windows can be one of the main source of heat loss in your home, with an estimated 10% being lost directly through the windows, and a further 15% as draughts. If you live in a conservation area where you have to retain your sash windows, or cannot afford double glazing, secondary glazing can offer a practical and affordable option.

What do we mean by secondary glazing? Essentially it means installing a second layer of glass or plastic on the inside of your windows. Often this is installed in such a way that it can be easily removed over the summer months. As well as offering a reduction in heat loss and draughts, it can bring significant improvements when it comes to sound insulation too. There are several different options available, depending on your DIY skills and financial investment. 



You can do all the work yourself, as one of our householders Kester did (see Left). He used UV resistant polycarbonate sheets, cut to custom size by a local Bristol company. He attached magnetic tape to these sheets and to his window frames, allowing easy removal of the panels for the summer months. 

Coming in at just £75 per panel, he believes this is the most cost-effective part of his retrofit. “Immediately after installation I found I had to turn the central heating timer down to half the cycle because it was unbearable hot, and it’s also stopped draughts.” He warns against cheap magnetic tape, advising that it might lost its magnetic strength over time. He also points out that polycarbonate scratches easily, so you need to be careful when fixing the panels in place, and to make sure you buy UV resistant polycarbonate, or it will turn semi-opaque over time. Would he do it again? “Yes, but I’d consider using wooden frames, and clean the frame with meths beforehand so the glue sticks better”.

Another householder who opted for internal glazing is Dan (see Centre). He installed secondary glazing on a bay window in his house, finding it was more affordable and less disruptive than double glazing. He bought the glass, cut to size by a local business, and used the EasyFix attachment system made up of a rubber edging strip and clips, which he used to install the windows himself. “It’s so unobtrusive”, he points out. “We leave them up over the summer, only taking down the central panel to allow us to open one window for ventilation.” His panels cost £130 each, but he had to plane the staff bead on the inside of the sash window frame to ensure the panels fitted snugly. He has found the glazing has definitely reduced heat loss and made the rooms quieter, and has gone on to install secondary glazing elsewhere in his home.

Angela  (see Right) opted for the CosyHome Company system. Sheets of plexiglass are customised to your windows and fixed in place with magnetic strips. What is unique about the design is that it allows you to still open your windows with the secondary glazing in place, and their sash window system fitting service also includes a ‘service’ for your windows where chords, weights, beading and brush strips are all replaced as required. As plexiglass is seven times more insulating than glass, the system offers a 70% reduction in heat loss over single glazed windows. This is the most expensive option, but appeals to people who want a high quality appearance and retain year round easy operation of their windows. Householder Angela says, “With the secondary glazing it's easier to keep the house warm. We used to have to put the heating on in the sitting room AND light a fire before we could use it, now we can do just one.”

If you live in a period home and want to find out more about the different secondary glazing options available, come to our event on the 4th February. You'll be able to find out more about the benefits of secondary glazing, speak to members of the planning department about regulations, see first hand the CosyHome system installed in Angela's home, and get further information and advice about other available systems. You can book onto the event here


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