Measuring a double glazed sealed unit correctly is essential for ensuring a proper fit and avoiding costly mistakes. Whether you’re replacing a failed unit or ordering new glass, accurate measurements will save time and prevent issues during installation.
This guide walks through the basic steps for measuring a double glazed sealed unit safely and accurately.
Before you start, gather the following tools:
In some cases, you can measure the sealed unit while it is still in the frame. However, for the most accurate results—especially with older windows—it’s best to remove the glazing beads and measure the unit itself.
Always measure the glass, not the frame.
Measure the visible glass from edge to edge:
Take each measurement in at least two places and use the smallest figure. This accounts for any movement or distortion in the frame over time.
Record all measurements in millimetres.
To determine the thickness of the sealed unit:
If the unit is still installed, you may need to check the spacer bar or manufacturer markings to confirm the thickness.
Look at the spacer bar inside the sealed unit and note:
This information helps ensure the replacement unit matches the existing windows.
Before placing an order:
Tip: Measure twice and order once. Incorrect measurements are one of the most common causes of delays and wasted units.
Accurate measuring is the foundation of a successful sealed unit replacement. Taking your time and following a consistent method will help ensure the new glass fits correctly and performs as expected.
If you’re unsure at any stage, it’s always best to consult a professional glazier.
