Is Secondary Glazing Second Best?

Secondary glazing is a double glazing alternative in Melbourne.

Firstly, What Is Secondary Glazing?

According to the Collins English Dictionary, secondary glazing is “insulation by means of a second pane of glass, or a sheet of plastic: a simple form of double glazing“. It’s defined elsewhere as “Any glazing added to an existing window, that forms a double window.”

Although it’s sometimes called ‘secondary double glazing’, it’s not genuine double glazing, which is always defined by the vacuum or argon gas-filled gap between the glass panes.


When is Secondary Glazing Employed?

Secondary Glazing is generally chosen over true double glazing as people tend to believe this is a cheaper alternative than genuine double glazing. Fortunately this is not the case. Often genuine retro fit double glazing (TwinGlaze) is very competitive if not cheaper than most secondary glazing products.


What Forms Does Secondary Glazing Come In?

For those with almost no budget to spend, the cheapest form of double glazing is the DIY plastic-film-and-adhesive tape solution. With this approach, the customer cuts some thin plastic film, sticks it to the window with adhesive tape, and uses a hair dryer to shrink it taut. This is obviously cheap, but not highly effective. It’s certainly not the best option if you have kids or animals in the house, and far from the best if you enjoy your views.

Not for the house-proud, but a cheap option.


Another approach is to fit magnetic strips on the inside of an existing window, and use an acrylic pane with a magnetic frame to attach to the stripping. This is more expensive than the DIY approach above, but cheaper than a genuine double glazed window with a new frame. As with most things, where you have a lower price, you usually compromise features and performance. See below…


What Are The Limitations Of Secondary Glazing?

The best way to answer that question is to list the benefits you receive with a genuine double-glazed window or door, and note whether the secondary glazing provides that benefit. Here are some of the benefits of a genuine double- glazing unit

  • The outside glass pane will most likely be thicker than your existing glass pane. Stronger, and providing more insulation. Secondary glazing can’t improve your outside pane- you’d have to pay extra for that.
  • The outside pane can be specified as toughened glass where necessary. Secondary glazing can’t improve your outside pane- you’d have to pay extra for that.
  • The outside pane can be fitted with Low-e glass. Secondary glazing can’t improve your outside pane- you’d have to pay extra for that.
  • Your new double-glazed window will come with a new, low-maintenance, efficiently- insulating frame. Secondary glazing can’t upgrade your frame- you’d have to pay extra for that. Of course, if your existing frames are aluminium, then secondary glazing can’t prevent much of the heat transfer occurring.
  • New double-glazed windows will enhance your home security. Add-on secondary glazing solutions add nothing to window security, which in most homes is minimal.
  • The high thermal insulation efficiency of genuine double glazing is ensured by the use of vacuum, or argon-filled gaps between the window panes. Secondary glazing simply can’t provide this. No genuine double glazing manufacturer we know uses an air gap, but secondary glazing has to settle for it.

As Ric Butt, past President of the Royal Australian Institute of Architects says,

“Double glazing will differ depending on the design and whether it is to the north, east or west. With good passive solar design, you will have a low ‘U’ value and a high SHGC to the north to allow winter sun in and to the east/ west windows, you will have both a low ‘U’ value and a low SHGC stopping summer sun.”

Your Three Main Double Glazing Options:

Secondary Glazing

It’s not real double glazing, but if the capital cost of making your windows more energy-efficient means that you can only afford secondary glazing, then that’s your choice.

Remember that the whole of life cost of a double-glazing product includes maintenance costs of the product and the existing frames, and how much energy and money you save.

Retrofit Real Double Glazing

Recently, a fascinating new product has come onto the double glazing market. It’s a real/true/genuine double glazing unit (IGU) that’s made to fit into your existing frames- if they’re up to it.

As long as your existing frames are in good condition, and suitable, TwinGlaze can provide you with a custom-made double-glazed widow or door unit, for less money than the traditional units and frames. Twinglaze supplies it’s better-than secondary glazing to Melbourne, Canberra and Sydney.

The TwinGlaze True Double Glazing retrofit option- custom-made & fitted to your existing frames.


Genuine Double Glazing

Overall, it’s clear that the greatest range of features and benefits come with genuine double glazing. Perhaps it’s a reminder of the old saying, “Price is what you pay. Value is what you get.”

We would love to help you with any questions you may have, and help you to enjoy the advantages of fitting your home with double glazing. Give us a call on or fill in the Contact Form. If you’re ready for a Quote, click here…


Double Glazing is ideal in the Melbourne climate.

 Posted on : August 10, 2015