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Double Glazing Thickness

uPVC Windows with Double Glazing

When deciding whether or not to install new windows, the thickness of double-glazing units is often not a factor that many property owners consider.

The Thickness of double glazing will usually depend on the material the windows are made of.

uPVC windows and Aluminium windows are typically 28mm thick, however, some systems may allow for slighter thicker or thinner sealed units.

The double glazing in wood windows can vary greatly.

What is the standard thickness of double glazing?

The standard thickness of most double-glazing units is 28mm. This is the most common size and fits most modern uPVC and aluminium windows and doors precisely, ensuring a perfect fit.

What is the minimum thickness of double glazing?

The minimum thickness for double glazing is 14mm. This size unit is usually found in old Timber or Aluminium systems.

The minimum thickness of double glazing for UPVC is 24mm.

The thickness of the double glazed units is dependent on the system.

For example;

Standard UPVC Casement Windows use 28mm sealed units, whereas Flush UPVC Casement Windows use 24mm sealed units.

What is the maximum thickness of double glazing?

The maximum thickness of double glazing is generally 40mm. This size is rarely seen, as it is much thicker than most windows will require and could potentially cause a number of installation issues.

It should also be noted that larger units can become quite heavy and may need additional support to hold them in place. Additionally, this size of double-glazing will provide more insulation than necessary and may not be as cost-effective in the long run.

Overall, for most window frames, 28mm thick double glazing is more than enough to ensure a great level of insulation and protection from the elements and is usually the maximum thickness standard uPVC, and Aluminium windows can hold.

How to Measure Thickness of Double Glazing

The only reliable way to know the thickness of your existing double-glazed units is to measure it.

To measure the thickness of your existing double-glazed units, you will need to remove the glass from the window or door. This is done by first removing the beading. Once the beading is removed, use a tape measure to determine the total thickness of your double-glazing unit.


Our uPVC and Aluminium window systems allow for 28mm thick sealed units, These are A-rated as standard and can achieve a u-value of 1.4W/m2.K.

If you’re interested in getting a free quotation for new double glazing, please send us your window sizes and specifications at [email protected], and we’ll get back to you as soon as we can with an estimate.

Astraframe supplies Double Glazing Windows in Norwich and manufactures uPVC Windows, Doors, and Conservatories. We supply premium quality products for up to 50% less than national retail companies.



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About Us

Astframe is a uPVC Windows & Doors manufactured based in Norwich.

We supply a range of premium quality products including uPVC Windows, Doors, and Conservatories. Aluminium Bi-Folding Doors, Patio Doors.

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