How thin can double glazing windows & frame be?

3 min read Windows

The thinnest standard double-glazed windows can be is 14mm, made up of two 4mm glass panes and a 6mm spacer bar. However, there are exceptions to this rule and windows do not always come in standard sizes. We have investigated this issue in more depth below to give you an idea of just how thin they can be.

Standard thicknesses of double-glazed windows

pvc alternative cross sectionThe overall thickness of double glazing is determined by the depth of the 1st pane of glass plus the spacer bar and the 2nd pane of glass. You might have seen this written out as a notation like 4 – 12 – 4, which means a 4mm pane of glass, 12mm spacer bar, and 4mm pane of glass, resulting in an overall depth of 20mm. We have listed some of the standard sizes that you can expect to see for double glazing in residential properties below:

  • 14mm (4-6-4)
  • 16mm (4-8-4)
  • 18mm (4-10-4)
  • 20mm (4-12-4)
  • 22mm (4-14-4)
  • 24mm (4-16-4)
  • 28mm (4-20-4)

The cavity between the two panes of glass is also filled with Argon or Krypton gas. These gases have low thermal conductivity, so they help double-glazed windows trap more heat, resulting in warmer homes that cost less to heat.

How thin are aluminium windows?

Aluminium double glazing is available with a super slim overall depth of 14mm. As aluminium has one of the best strength-to-weight ratios of any material, aluminium window frames can be built to slender proportions whilst still being to support the glazing. A modern solution for brightening up your home, here at Sheerwater Glass, we have a wide range of aluminium windows available for fitting.

How thin are uPVC windows?

For standard double-glazed uPVC windows, the thinnest their overall depth can be is 20mm. This is made up of two 4mm panes of glass which are separated by an 8mm spacer bar. However, there are thinner options available.

Take our uPVC slimline windows, for example, which are of a similar thickness to single glazed timber windows (the standard thickness for single glazing ranges between 3-12mm). So, for anyone looking for an ultra-slim window solution, they are perfect!

Our exclusive uPVC slimline windows

Upvc casement window roasewoodOur exclusive uPVC slimline windows boast of a contemporary design, epitomized by the super-slender frames that you usually find on aluminium windows. With 12% more glass than standard windows, they let more light flow inside. They also feature the latest double glazing and multi-chambered profiles, so they offer outstanding Window Energy Ratings of A+ too. So, you can expect your home to feel warm and comfortable as well as stylish and bright.

Slimline uPVC and aluminium windows installed in and around Surrey

Are you interested in new or replacement windows for your home? Sheerwater Glass can help. For more information or a free quote, give us a call on 01932 344 415 or contact us online.


Read what we have to say about windows  

Are aluminium windows thinner than uPVC?

What are the standard window sizes in the UK?

The types of windows guide (and which are the best!)

How effective is double glazing at reducing noise?


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