Steps to Replace Windows

When replacing a window, the most important step is to do proper measurements. While the other steps, including trim removal, unscrewing the flanges, and replacement steps are also essential, in this resource article, we are focused on the proper steps for measurement.

You may be asking yourself the best way to measure a window for replacement. This can seem overwhelming, especially if you have never replaced a window before. 

How to Measure for Replacement Windows the Correct Way

Simply using a ruler or tape measure to quickly measure your window is not proper.

The most precise measure steps include:

1. Measure the width, in three places: top, middle, and bottom. Measure from one jamb to the other. These are the vertical sides of the window opening. Don’t measure the window frame/sash itself, as this sticks out beyond the jambs.

2. Next, measure the vertical height, from head (top) to bottom (sill). Measure at both sides and in the middle.

3. Measure depth. This is especially important if you are going to go with a high-end thick framed window. From the frame to the inside edge of the window box. 

Width and height are the most important. Note the smallest measurement. This is how you do window measurement. The right window size is dependent on it.

Take the smallest of each of these three numbers. When ordering your window, the manufacturer typically reduces it a small amount, which makes the window fit almost perfectly in the existing space.

Why three spots of measurement? There are often imperfections in a window box. By choosing three places, the window is most likely to have an accurate measurement.

There are a few minor situations you should be aware of that could change how you take measurements:

Measuring a Window to Expand or Reduce

Although you may wonder how to measure a window to replace if you are wanting to add a larger (or smaller) window, that would be the time to do it. You still need to measure window width and heights. Adding a larger window can happen in several ways:

Minor changes within the window box frame

Some replacement window installs can allow for a slightly different size window (typically within an inch or two) within the same framed window box. This can be achieved either through removing some of the wood framing thickness by cutting it out or if making a slightly smaller window, adding shims and other fillers. Chances are, any replacement window will need a small amount of these adjustments. It won’t require reframing, just using tools that cut into the wood framing a little, (or filled) to accommodate the new size.

Changing the height

If you want to add a taller window, this is usually much easier than a wider window. It won’t require engineering and load-bearing stud concerns. Just simply lower the sill frame to accommodate a taller window. You’ll benefit from more window space, perhaps being more reachable, and greater views and light, with little to no structural changes to the home.

Changing the width

On the other hand, if you want a wider window, this may affect the load-bearing studs that are around the window. Careful thought and possible engineering plans would need to be considered for a substantially wider window that requires cutting into additional vertical studs. Measure width: When measuring, try to bring the width up close to the next further stud, but not fully past it. This will avoid issues of unwanted reengineering. 

Changing both width and height

This is the most complicated but could leave you with a large impressive window. This is ideal for the replacement windows of small living room windows that can be converted into large high-profile windows to create a statement to the neighborhood. 

Having a Window Installer Help You

However, if you are choosing to go with a professional window installer, they should be able to come out, on-site, and do the proper measurements for you. This eliminates the fear of having wrong window measurements. This gives you the assurance that the warrantied work is based on their measurements, not yours. Then you can have the peace of mind that it is measured properly.