Door and Window Measuring

Door and window measuring is strictly advised for an experienced tradesman or a proficient DIYer. 123door, Belfast is not responsible for any discrepancy in measurement or inaccurate survey.
It is recommended that you call us for installation of your door accurately and properly. We have an efficient team that will install your door with minimum fuss and in a short time.

This guideline is made available to help you in the installation of your door. We are not responsible for any inaccurate survey.

For the height (H)- measure from the sill to the underside of the exterior trim at the top.
For the width (W)- take the measurement from three points. Measure from the top, center and bottom of the door opening.
For thickness (T)- measure for the thickness of the door frame in all the corners.

Make 5mm allowance for the sealing of the door frame on all sides.
Deduct 10mm from the final measurements of the height and width.

Measure the diagonals properly. They help you to make sure that the opening for the door is in a proper square shape. If the diagonal measurement is way off that is more than 6mm, then your opening is not in a proper square shape and will create problems for you in the installation of the door.

If your door has modification such as side panels or top light, then make sure that you incorporate them in your measurement for the door installation.

For side panel- the width should be measured from the center point of the frame between the door and side panel to the outer edge of the side panel.
For top light- measure the depth from the center point of the frame between the door and the top light to the top of the door frame.