Double Glazing Unit Replacement

 

 

double glazing replacement units

Double Glazing Unit Replacement: A Complete Guide for Homeowners

Double glazing unit replacement is one of the most cost-effective ways to restore thermal efficiency, eliminate condensation, and extend the lifespan of existing windows without the expense of a full-frame replacement. Whether you are experiencing misted panes, cracked glass, or reduced insulation performance, understanding the process will help you make informed decisions and avoid unnecessary costs.

This guide explains what a double glazing unit replacement involves, how to assess whether you need one, and what to expect during the measuring, quoting, and installation stages.

What Is a Double Glazing Unit Replacement?

Double glazing unit replacement refers to replacing the sealed unit—also known as a double-glazed unit (DGU) or insulated glass unit—inside the existing window frame. The frame itself remains in place, making this solution significantly cheaper and less disruptive than replacing the entire window.

Sealed units typically consists of:

  • Two panes of glass

  • A spacer bar

  • A sealed air or gas-filled cavity (often argon)

When the seal fails, the unit loses efficiency and must be replaced.

Signs You Need a Double Glazing Replacement

You may require a replacement unit if you notice any of the following:

  • Condensation or fogging between the panes

  • Cracked, chipped, or scratched glass

  • Draughts near the window

  • Reduced thermal insulation

  • Discolouration or visible moisture in the spacer bar

These symptoms indicate that the seal has failed or the glass has been compromised.

How to Measure for a Replacement Unit

Accurate measurements ensure the new unit fits correctly. You will need to determine:

  • Width of the sealed unit

  • Height of the sealed unit

  • Glass thickness (common sizes range from 24mm to 28mm, though others exist)

  • Glass type, such as:

    • Standard clear

    • Low-E (energy efficient)

    • Toughened or laminated

    • Acoustic glass

    • Argon-filled or other performance options

  • Spacer bar colour (typically silver, black, or grey)

If you are uncertain please contact us.

Should You Choose Professional Installation or DIY?

Professional Installation

Most homeowners choose professional glazing companies for replacement due to accuracy, safety, and warranty benefits. Professionals manage the full process—from measurement to installation and disposal of the old unit.

DIY Replacement

DIY installation is possible for those with strong practical skills. It typically requires:

  • Glazing suction cups

  • A putty knife or thin pry tool for bead removal

  • Replacement packers

  • Safety gloves and eye protection

However, certain frame types (particularly aluminium and some uPVC designs) are not DIY-friendly. When in doubt, use a qualified installer.

Obtaining Quotes for Double Glazing Unit Replacement

To ensure you receive competitive pricing, request quotes from:

  • Local glazing companies

  • Specialist window repair contractors

  • Online manufacturers who produce sealed units to order

When evaluating quotes, verify that the following are included:

  • Precise measurements

  • Manufacturing of the replacement unit

  • Installation

  • Removal and disposal of the failed glass

  • Warranty coverage on the new unit

Pricing varies depending on size, location, and glass type. If you would like a quote then please contact us for a free quote

The Double Glazing Unit Replacement Process

A standard replacement involves:

  • Removing the internal window beads.
  • Lifting out the old double-glazed unit.
  • Cleaning and inspecting the frame.
  • Installing packers to ensure the correct alignment of the new unit.
  • Fitting the replacement sealed unit.
  • Reinstalling the beads securely.
  • Inspecting the window for proper sealing and operation.

The process is typically completed within 20–40 minutes per window.

Benefits of Replacing the Sealed Unit Instead of the Whole Window

  • Lower cost compared to full window replacement

  • Restores thermal performance

  • Eliminates condensation between panes

  • Extends the lifespan of existing frames

  • Improves energy efficiency and comfort

For many homeowners, double glazing unit replacement is the most economical and effective way to maintain the performance of their windows.

Preston Glass and Glazing have a great deal of experience of all types of double glazing so don’t hesitate to contact us if you have any questions or queries.

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