Measuring Home Windows for Replacement

You've recognized that your windows are old, energy inefficient, and in desperate need of replacement. However, you are on a tight budget, and can't afford to hire someone to replace them. What do you do? You replace them yourself. This is not a difficult process, but it does have to be meticulous. The first step in this process is to measure your existing windows so that you can order new ones. When ordering replacement windows for your home, your measurements must be precise. The closer the new windows fit the existing opening, the less you will risk cold drafts during the winter and future maintenance. Here are the four steps involved in measuring home windows for replacement.

Label Your Windows
If you are measuring and ordering multiple windows at one time, mixing up your measurements can be easy to do, further complicating the task. A good rule of thumb is to begin by labeling your windows and then write down the corresponding list of measurements. You can do this by using post-it notes or writing on the glass with a dry-erase marker. The more organized you can be in this process, the better.

Measure Horizontally
When ordering home windows for replacement, the window's width is listed before the height. So, it is best to begin by measuring your window's width. Identify the first window that needs replacement. Using a tape measure, measure the width of your window in three different places. You should measure horizontally from one inside edge of the frame to the other inside edge of the window jam. Take the width measurement at the top, in the middle, and across the bottom of the frame. Write down each of these measurements. The smallest of the three is the one you want to use, so circle it. This is what's called your "rough opening width", and it will be the primary reference measurement when ordering your new window.

Measure Vertically
The second measurement used when ordering new windows is the vertical length of the frame. In the same manner as you took the width measurement, measure the height of the existing window. Measure the distance from the top inside edge of the frame to the bottom edge inside the wooden window jam. Measure from top to bottom on the far left side, in the middle of the window frame, and on the far right side. Once again, identify the smallest of the three measurements and circle it. This will be your "rough opening height."

Measure Depth
The last measurement to take is the depth of your window. This measurement is the most important of the three but can also be the trickiest to find. This measurement is vital because some new window casings can be too deep to fit into an existing opening. This will prevent the window from having a tight seal to the framing of the house.
To take this measurement, start by opening your window. Use your measuring tape to measure the distance from the inside edge of the frame to the outside edge. Take this measurement in at least four places on each side of the window. Then circle the smallest distance. This will be your "rough opening depth."
If you cannot open the window, this measurement will require some simple math. Measure the depth of the frame on both the inside and the outside of the window. Do this on all four sides of the frame. (If it is not a window on the ground floor, then a ladder will be required). Once you have the inside and outside depth of the frame, add an estimation of the depth of the glass. Single-paned residential glass is typically 1/8 inch or 3mm thick. Add this estimation to your four sets of measurements and identify the smallest number as your rough opening depth.

Order Your Windows
Once you have your rough opening width, height, and depth, you can begin shopping for replacement windows. Keep in mind the style of your home, how energy efficient you want the windows to be, and how much security you want them to offer. Once you have that information, you should be all set!