Measuring for Your Replacement Door

How to Measure for Your New Door

Are you ordering your new door from Building Plastics Online Ltd? Getting the measurements right is essential for a smooth and successful installation. Below is a simple step-by-step guide to help you measure accurately for your new front or back door.

What You’ll Need:

A metal tape measure (for accuracy)
A notepad and pen (to write down your measurements)
A level (optional but helpful for double-checking frames)

Step 1: Measure the Width

Measure the brick-to-brick opening across the width in three places – top middle and bottom.
Record the smallest of the three measurements. This will ensure the door and frame fit even if the opening isn’t perfectly square.

Step 2: Measure the Height

Measure from the bottom of the opening (where the threshold sits) to the top brickwork in three places – left, centre, and right.
Again, could you record the smallest measurement? This avoids issues if the opening height varies slightly.

Tip: If your existing door has a sill or threshold you’re keeping or replacing, include that in your height measurement.

Step 3: Allow for Fitting Clearance

We recommend subtracting 10mm from the width and height to allow for a comfortable fit and room for packing or sealing. This helps with easy installation and avoids forcing the frame into place.

Step 4: Choose Your Hinge Side and Opening Direction

From outside the property, decide:

Which side you want the hinges on (left or right)
Whether the door should open inward or outward

This will ensure your door opens just how you need it to and suits your space.

Step 5: Consider the Sill Option

We offer different threshold options depending on your needs – including low mobility thresholds and full sills. Be sure to consider what works best for your project or accessibility needs.

Measuring for a Door with Side Panels or Top Lights?

If you're ordering a composite door with side panels or a top light, measure the total width and height of the opening above. Based on what you're doing, we'll work out the individual panel sizes during the manufacturing process.

Need Help or Not Sure?

If you’re unsure about anything or want us to double-check your measurements, please get in touch with our expert team at Building Plastics Online Ltd. We're happy to help guide you through the measuring process so you can order confidently.