Double glazing on a budget

DIY double glazing

Double glazing can be very expensive, but with a bit of care and patience you can add double glazing to existing windows without breaking the bank. Alan Cotterill shows us how.

Built in 2002, my four-bedroom brick veneer house has stock standard powder-coated aluminium windows and doors. With my previous efforts to retrofit for energy savings and thermal comfort (see ‘Efficiency on a budget’ in ReNew 130), I had already fitted effective shading for my windows in the warmer weather. As I understand it, this is a prerequisite if double glazing is not going to be counterproductive in summer. But for winter, double-glazed windows insulate and thus hold in the heat much better than a single-glazed pane. Thus, I embarked on a project to retrofit my windows with a second (acrylic) pane.

Materials
For the additional panes, I used 3 mm cast acrylic sheet accurately cut to size commercially by The Plastics Factory. They cut 34 panels within a tolerance of 1 mm to my requested dimensions. Accurate measuring by myself was of paramount importance for this! Buying direct from a wholesaler meant a good saving; in fact, the cost was around half that of uncut sheets from local retail outlets.

I adhered the acrylic sheet to the aluminium surrounds of each panel of glass using highly flexible silicone sealant. The reasons for this choice were two-fold.

Firstly, the linear expansion rate from a change in temperature is significantly different between the acrylic sheet and the aluminium frame, with the acrylic expanding at three times the rate of the aluminium. With a 1200 mm edge and a temperature change from 0 to 40 °C, the acrylic would expand nearly 4 mm more than the aluminium frame. Flexibility of the sealant would cater for this to some extent.

Secondly, if a glass panel needs replacing down the track or a return to single glazing is desired, the silicone sealant could be scraped off (although still a tedious, fiddly job!)

Read the full article in ReNew 135.

Prize ReNew sub banner

×