Why Accurate Window Measurements Matter
Gone are the days of waiting for a site survey just to get a price for your new timber windows. Instead of booking appointments and dealing with delays, you can now take control of the process yourself. With the Wooden Windows online designer, simply enter your window measurements, choose your preferred style and finish, and receive an instant visual and quote, ready to order whenever it suits you.
This streamlined approach removes unnecessary waiting time, making it faster and easier to plan your replacement or new timber flush casement, stormproof or sliding sash windows.
Measuring your windows is straightforward too, just follow our simple step-by-step guide below to get accurate sizes with confidence.
How to Measure Casement Windows
Step 1: Measure the width
Where possible measure the distance from brick to brick, taking measurements at several points: top, middle and bottom. Use the smallest one of these sizes and deduct 10mm - this will be the width of your new window.
Step 2: Measure the height
Exactly the same as above, take several measurements and deduct 10mm from the smallest size - this will be the height of your new window.
Measuring from the brickwork is preferred, but alternatively you can use sizes from your existing frame - measure in 3 places and use the smallest sizes (in this case you would not need to deduct 10mm). Please note if you are taking sizes from your existing frame make sure you measure the actual frame and not any timber which may have been planted on after. If you have a lintel also take this into account when measuring.
Pro Tip: Measure From Outside
If you are replacing existing windows you should, in most cases, take measurements from outside the property. Plasterboard will be butted up to the frame on the inside making it impossible to take accurate sizes.
How to Measure a Window (Quick Steps):
- Measure the width & height from brick to brick in 3 places
- Use the smallest measurement
- Deduct 10mm for fitting clearance
- Repeat for height
- Always measure from outside where possible
What If You Can’t See the Brickwork?
If you are struggling to find the brick work, for example on a rendered property we recommend chipping away a small amount of the render at either side of the window thus exposing the brick (this render would need to be removed anyway when replacing the window).
Common Window Measuring Mistakes
- Measuring from inside instead of outside
- Forgetting to deduct 10mm
- Measuring plaster instead of brick
- Not checking all 3 points (top/middle/bottom)
Download your free measuring guide for casement windows
Watch the video with step-by-step instructions on how to measure for your replacement casement windows
Get an instant quote using our standard online window designer
How to Measure Sliding Sash Windows
Understanding the Window Reveal
Traditional sliding sash windows are fitted into a reveal or recess in the brick work, both up the sides and across the head (top of the window). There is no recess at the bottom of the window, the cills are designed to sit on a flat surface.
When ordering a sash window you will need the total window size so it is important to take into account the amount of window sitting hidden behind the reveal.
Spiral vs Weighted Sash Windows
We would recommend showing approx 25mm of the outer lining of the sash box:
- Sliding sash with weights and pulleys has a 110mm wide frame section, therefore you would need to add 170mm to the width of the outside brickwork.
- Sliding sash with spiral balances is much slimmer - a 60mm wide frame section, therefore you would need to add 70mm to the width of the outside brickwork.
Measuring Width for Sash Windows
Check the internal width and height are larger than external. It is also advisable to expose the overall size of the window by removing the internal architraves or linings, this can be a reassuring way to ensure that the windows are the correct size.
See the first two drawings above showing a sliding sash window sitting within the reveal (recess).
Measuring Windows for New Build Properties
New build properties tend not to have a brick recess for sliding sash windows, this is because they are designed to take spiral balance sash windows which can be fitted in a more conventional way, so the usual tight brick to brick measurement less 10mm clearance is the way to go with this.
Download your free measuring guide for sliding sash windowsGet an instant quote using our Sliding Sash Window Designer
FAQ’s
What tools are needed to measure for replacement windows?
Minimal tools are needed when measuring for your new windows. Here is a checklist to make sure you are ready-to-measure.
- Step ladder (take care if measuring windows at height and get support from a second person)
- Measuring tape - sturdy and at least 3m long
- Notepad & pen - to record measurements
- Spirit level - to check if your openings are level
Who should I ask to install new timber windows?
You should always get in a professional craftsman either a carpenter, joiner or professional window installer to install your new windows. This ensures your windows are installed correctly to UK building standards and it will also help protect your warranty. If the windows are fitted incorrectly you might not be covered and this could affect the longevity and performance of your windows.
How do I order new windows?
You can order your new timber casement windows online with the online window builder where you can submit your measurements, select your window style and finish and get an instant visual and quote.
How long does it take for my new windows to arrive?
If you order your new windows with Wooden Windows, you can expect delivery within 2-4 weeks depending on the finish of your windows. For bare or primed windows 2 weeks and for fully painted windows (recommended) 4 weeks. Delivery is taken care of by the wooden windows transport fleet and you will get a set day and estimated time window with regular updates to ensure you can plan your window install perfectly.
Need Help Measuring Your Windows?
Should you require any further assistance in measuring sliding sash windows or any other type of window, please don’t hesitate to contact our team. Send photos of your windows and we’ll talk you through it.
Email: hello@woodenwindows.com or call: 01782 644871