Double Glazing Explained
Double Glazing Explained
What should I be asking when considering retrofit double glazing?
Retrofitting double glazing should be carried out by a skilled professional who can ensure that appropriate Building and Glazing Standards are followed in completing the work for you. Here are some things to check in advance of approving the work:
What will your windows and doors look like when they have been double glazed?
Ask to see the changes in place so that you can check first-hand if the glass area will change and the overall aesthetics. Most windows should have no reduction in viewable glass area. Some doors (e.g. sliding doors) may have a small change. The finished outcome should be one where the changes maintain or enhance your home’s appearance – and don’t just look like an add-on.
What is the width of the space between the two pieces of glass in the double glazing unit?
This should be at least 10mm and not more than 16mm (the optimal space with air filled double glazing is 14mm and with argon gas is 12mm). If the space is too small, the cold will more easily travel through the double glazing from one side to the other. If the space is too large, then convection currents are set up inside the double glazing resulting in reduced thermal performance. A 12mm space provides 8% better thermal performance than an 8mm space.
What is the spacer in the double glazing made of?
The material of the spacer makes a difference to the insulation performance (thermal and noise). The best performing spacers contain no metal. This is important for both timber and aluminium frames and will make a noticeable difference for condensation reduction.
What are the options available that can help address other issues at the same time?
Consider options for improved sound control, reducing fading and enhancing security.
What is the warranty being offered – on the double glazing and on the workmanship?
Double glazing manufactured by members of the Insulating Glazing Unit Manufacturers Association (IGUMA) has to meet BRANZ tested standards and comes with a 10-year warranty.
How long has the company been doing this work (retrofitting double glazing) and are they members of the Window Association of New Zealand?
WANZ (or GANZ) membership provides you with an assurance of industry standards being met with quality workmanship and good service. Previous customers can also be a great reference for the quality of work and service that you can expect to receive.