- Accurate measurements are crucial for replacement casement windows – even small errors can lead to ill-fitting windows.
- Always measure at three different places for both height and width to account for any irregularities in the window aperture.
- Measure the depth of your frame to ensure your new windows will fit properly within the existing structural support.
- Record all measurements in millimetres for the most precise fitting, as this is the industry standard.
- Professional window installers like Double Glazing Direct can conduct a full survey if you’re unsure about taking measurements yourself.
Replacing your casement windows can transform the look and energy efficiency of your home.
But before you get excited about your beautiful new windows, there’s an important first step – getting the measurements right.
At Double Glazing Direct, we know that accurate measurements are the foundation of a successful window replacement project.
Whether you’re considering uPVC, aluminium, flush casement windows, etc, this guide will help you take precise measurements to ensure your new windows are a perfect fit.
The simplistic design of a casement window is one of the reasons why they’re the UK’s most popular window style.
Tools You’ll Need
Before you start measuring, make sure you have the following items:
- A reliable tape measure (metal ones are best)
- A notepad and pen to record measurements
- A spirit level
- A ladder (if measuring upstairs windows)
- A helper (recommended for safety and accuracy)
Step-by-Step Measurement Guide
- Measure the Height
Start by measuring the height of your window frame from the bottom of the window to the top. Take measurements at three different places – the left side, the middle, and the right side. This accounts for any irregularities in the frame or if the window isn’t perfectly square.
Always record the smallest of these three measurements, as this ensures your new window won’t be too tall for the opening. Note your measurements in millimetres for the greatest accuracy.
- Measure the Width
Similarly, measure the width of your window at three different places – the top, middle, and bottom of the window frame. Again, note the smallest measurement to ensure your replacement window will fit within the existing aperture.
Remember to measure the full width including the frame itself, not just the glass area or sash. If your window has a mullion (the vertical bar between panes), make note of its position too.
- Measure the Depth
The depth of your window frame is just as important as height and width. Measure from the front face of the window to the back to determine the frame depth. This ensures your new windows will have proper structural support and fit correctly within the wall.
For timber casement windows, this measurement is particularly important as frame depths can vary significantly.
- Check for Reveals and Obstructions
Examine the area around your window for any obstructions that might affect installation. Look for:
- Window cills that extend beyond the frame
- Any decorative brickwork
- Pipes or electrical fixtures
- Interior obstacles like radiators
Make notes about these features as they may impact the installation process.
- Record Your Measurements Clearly
Create a clear diagram of each window, noting all measurements. Label each window clearly (e.g., “Kitchen – north wall”) and include all three measurements for both height and width, as well as depth.
If you’re ordering multiple windows, create a separate diagram for each one, even if they appear identical. Even windows that look the same can have slight variations that are critical for a perfect fit.
Casement windows
Why Accurate Measurements Matter
Getting your measurements right is crucial for several reasons. First, it ensures your new windows will fit properly in the existing openings without needing costly modifications to your home’s structure. Second, correctly sized windows perform better in terms of energy efficiency and security. Finally, accurate measurements help avoid delays in your project timeline by preventing the need for reordering.
It’s worth noting that building regulations guidance may require specific performance standards for your replacement windows, and the exact size can impact compliance with these regulations.
Who are Double Glazing Direct?
At Double Glazing Direct, we’re the trusted experts in window replacement across Buckinghamshire, Hertfordshire, and Oxfordshire. While this guide helps you get started with measurements for your quotation, we always conduct our own professional survey before installation.
We provide a wide range of home improvement products including uPVC windows, aluminium windows, doors in composite, aluminium, and uPVC, conservatories, and more. All our installations are FENSA approved, and we’re proud to be accredited by Which? Trusted Trader and TrustMark.
For peace of mind with your window replacement project, contact our team on 01296 320252 or email sales@doubleglazing-direct.com. Visit our Aylesbury showroom to see our quality windows in person and speak with our knowledgeable staff who can answer any questions about your window replacement project.
