Sunday, 4 October 2015

Deconstructing double-glazing

It is easy to get a load of handy glass panes, for free from cast-offs.

This sized sheet of glass could be £30 upwards to buy, so as I need loads to glaze the summerhouse I am building, savings are to be made...

Where I live, people are ripping out their UPVC double glazed windows and reinstating the original style of window: out go efficient, but arguably incongruous white plastic-framed units and back in go sashes, etc. I'm ambivalent about this. Plastic-framed sealed-unit double-glazed windows generally do look a bit crap in older buildings, but they are great for thermal efficiency.

Whatever the merits of style-conservation versus warm houses, this trend means fruitful skipping. Wait long enough and plenty of quality glass can be found chucked out. Everyone wins.

To get the glass I want has just meant keeping an eye out for window units being chucked out. Sure enough they do. Here's a good one.

To get at the individual panes, you have to remove the sealed units.

This is easy, you just need to pop the seals. I'm using a decorators scraper/spreader blade, but a sturdy chisel works well too. In either case, care is needed to avoid hitting or levering the glass with the metal edges.

By popping the blade in and twisting, the seal can be levered out quite easily.


It can be tricky to get started, but once the blade is in, it just needs enough of the seal exposed to grab hold of.


Once all the securing seals are out, the unit will ease out quite happily. Generally these units are edged with sealant tapes and are not sharp, but care is advised. Occasionally, you get a unit that has raw glass edges. I've got scars to show for that.

Once it is out, the double glazed unit needs sawing in half to give two panes. The bonding is usually a mix of thin aluminium and polymer sealant. This is easy to saw through. Here I'm using a reciprocating saw, but a jigsaw or even a handsaw would do it.

Close-up, with geraniums...

Once the seals have been sawn through, the two panes come apart easily. Here, you can see that privacy glass units often only use the more expensive patterned glass on one side. The other pane is usually clear.

For normal clear-glass units, you get two matching panes from each unit - handy!

You also get a load of silicon rubber seals, which can also be useful...


  1. Ecostar Double Glazing specialises in UPVC double glazed windows and doors. Double Glazing Quote or URL

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  3. Nice one - I wanted to find out whether I could split the glass on a double glazed unit and here you are with the answer! THANKS.