How to Measure Windows Correctly?

Correct measurement of plastic windows plays an important role in their successful installation and subsequent functionality. Here, we will look at the basic steps and tips to help you measure window openings with maximum accuracy.

 

Window Openings with a Rebate

A rebate is a small protrusion in the window opening, usually about 5-6 cm, which equals ¼ of a standard brick. The rebate is located on the exterior side of the window opening and is used to cover the installation joint and partially the window frame. It provides additional support and helps position window frames more securely in the opening.

 

To measure a window with a rebate, you will need a tape measure, a pen, and paper to record the dimensions:

Measure the width of the window opening with the rebate. Add 3-6 cm to the obtained value. This will be the final width of the plastic window. Note that in this case, part of the window frame is hidden behind the rebate.

IMPORTANT! There are no standard dimensions for window rebates. Each builder may create them in different sizes. They can be 5-6 cm or even 10 cm or more. Therefore, when measuring windows, this fact must be taken into account. The amount the window will be hidden behind the rebate is chosen by the customer. If you are unsure or do not know what is best to choose, consult a specialist from the window company where you will be purchasing your windows.

If the opening is made with a rebate, there should also be a rebate on the top. For aesthetics, the window should be hidden behind the top rebate by the same distance as on the sides. Therefore, you need to measure the height of the window opening with the rebate. Add 2-3 cm to the obtained value (to hide the window behind the top rebate).

If the window is installed together with a drip and a window sill, take their dimensions into account as well. Thus, the final height of the plastic window is the height of the window opening with the rebate, to which we add 2-3 cm (top) and subtract 3-4 cm for the window sill at the bottom.

IMPORTANT! In all the described cases, the size of the installation joint was not considered when measuring the window. The installation joint is the technological gap between the wall and the window, which is filled with installation foam during installation. The size of the installation joint can range from 10 to 35 mm, depending on the installation conditions. Therefore, the final dimensions of the window need to be adjusted by this value.

 

Window Openings without a Rebate

Window openings without a rebate are flat openings without protrusions. In this case, the window frame is installed directly in the wall cutout, and dowels or anchors are used to secure it, attaching directly to the wall. Such openings are usually found in new buildings.

 

To measure a window without a rebate, you will need a tape measure, paper, and a pencil to record the dimensions. Follow these steps:

1. Measure the width of the window opening. Take measurements in three points: top, middle, and bottom. Record the smallest value from all the measurements. Subtract 1-1.5 cm from the smallest value for the installation joint. This will be the width of the plastic window.
2. Measure the height of the window opening. Take measurements in three points: left, middle, and right. Record the smallest value from all the measurements. Subtract 2-2.5 cm from the smallest value for the installation joint and 3 cm for the base profile. This will be the height of the plastic window.

If you already have windows installed and the window frame and installation joint are visible, it is sufficient to measure only the installed structure. This method is suitable for installing windows of the same dimensions, for example, during their replacement. However, note that the original dimensions of the window opening remain unchanged.

What is the Difference Between Measuring Windows with and Without a Rebate?

The main difference between window openings with a rebate and without lies in the measurement method. Measuring a window opening with a rebate requires considering the dimensions of the rebate itself, which may increase the window dimensions. In contrast, a window opening without a rebate imposes fewer restrictions and simplifies the measurement process, as measurements are taken directly of the window opening.