Accurate window measurements are crucial when ordering replacement windows, exterior shutters, or storm windows. Even small discrepancies can lead to gaps, drafts, or installation difficulties. By taking the time to measure correctly, you’ll save money, avoid frustration, and achieve better energy efficiency in your home.
This guide will walk you through the process of measuring window openings, providing you with the knowledge and techniques to obtain precise measurements for your window projects.
Essential Tools for Measuring Window Openings
To measure window openings accurately, you’ll need the right tools. The most important is a folding rule with slide extension. This is the most accurate tool for measuring window openings. A folding rule allows you to measure interior dimensions more precisely than a standard tape measure. The slide extension enables you to reach into corners and tight spaces, ensuring accurate measurements even in challenging areas.
While a folding rule is the primary tool, these additional items can be helpful:
- Tape measure (for rough measurements)
- Level (to check if the window is plumb)
- Pencil and notepad (to record measurements)
- Calculator (for quick calculations)
How To Measure Window Opening
To get correctly sized exterior shutters or storm windows, you have to provide the manufacturer or dealer with a precise set of window measurements. The way to do that is to take each opening’s measure at several points—old windows are seldom square. Follow these steps to ensure accurate measurements:
- Unfold the rule to the approximate width of the opening.
- Place the folded end against the inside edge of one side of the casing.
- Extend the slide to touch the opposite casing’s inside edge.
- Add the extension’s measure to the number at the other end of the rule.
- Record this measurement.
Once you’ve done the top, repeat the process at the middle of the window opening. This measurement may differ slightly from the top due to settling or irregularities in the frame. Take a third measurement at the bottom of the window opening. Again, this might vary from the top and middle measurements.
Always use the smallest of these three measurements when ordering windows or shutters. This ensures that the new unit will fit within the narrowest part of the opening.
How To Measure Height of Window
Measuring the height of your window opening is equally important. Again, you’ll want to take measurements at three different points to account for inconsistencies. Follow these steps:
- Position your folding rule vertically on the left side of the window opening.
- Measure from the top of the sill to the underside of the header.
- Record this measurement.
Repeat the process in the center of the window opening. This measurement may differ slightly from the sides. Take a third measurement on the right side of the window opening.
As with the width, use the smallest of these three measurements when ordering your windows or shutters.
How To Square a Window
Checking if your window opening is square is an important step that many homeowners overlook. Here’s how to do it.
- Measure diagonally from the top left corner to the bottom right corner of the window opening.
- Measure from the top right corner to the bottom left corner.
- Compare these two measurements.
Interpreting Your Results
If the two diagonal measurements are equal, your window opening is square. However, if there’s a difference, your opening is racked, which is common in older homes. A difference of up to 1/4 inch is generally acceptable, but larger discrepancies may require special considerations when ordering windows or shutters. Make sure that you let the company know this information when you place an order.
Special Considerations for Different Window Types
Different window types may require additional measurements or considerations. Here are a few of the most common.
Double-Hung Windows
For double-hung windows, measure the width and height as described above. Additionally, measure the depth of the jamb from the outside edge of the interior trim to the outside edge of the exterior trim.
Casement Windows
When measuring casement windows, ensure the window is fully closed. Measure the width and height of the entire frame, not just the sash. Also, note the direction the window cranks open (left or right).
Bay Windows
Bay windows require multiple measurements. Measure each section individually, including the angles between sections. It’s often best to consult with a professional for bay window measurements to ensure accuracy.
Sliding Windows
Sliding windows, which move horizontally, require specific attention. Measure the full width and full height of the window. Ensure you measure both panels if the window has two operable sections. Note any tracks or guides that might affect the fit.
Awning and Hopper Windows
Awning and hopper windows have unique requirements because they open outward and inward, respectively. Measure the full width and height of the frame. Also, consider the hinge location and operating mechanism as these influence the fit and function of replacement windows.
Common Mistakes To Avoid When Measuring Windows
Windows are expensive and sometimes take a while to fabricate, so you’ll want to be as accurate as possible. Here are some common pitfalls when measuring your windows:
- Assuming all windows in your home are the same size
- Measuring from the outside of the house
- Rounding measurements to the nearest inch
- Failing to measure in multiple places
- Not accounting for the windowsill when measuring height
By avoiding these mistakes, you’ll ensure more accurate measurements and a better fit for your new windows or shutters.
Other Important Measuring Considerations
Accurate window opening measurements are not just about width and height. Other factors play a crucial role in ensuring the correct fit of your new windows.
Measuring Window Depth
Another key measurement is the depth of the window frame. Measure from the interior to the exterior side of the frame. Depth measurements are particularly important for pocket or insert windows designed to fit inside the existing window frame. Measure at several points along the frame to account for any variations.
Sill Angle and Style
The window sill angle and style can affect installation. Measure the angle of the sill to ensure the new window aligns correctly with the existing structure. Confirm the style and thickness of the sill to ensure compatibility with your replacement windows.
Wall Thickness
Measure the thickness of the wall where the window will be installed. This measurement helps determine if any extension jambs or additional framing is necessary. Consider insulation and other factors contributing to wall thickness.
Tips for Ordering Replacement Windows or Shutters
When ordering replacement windows or shutters, keep these tips in mind to help you communicate better with the manufacturer.
Provide Exact Specifications
Beyond just the dimensions, be clear about other specifications. Inform the manufacturer of any unique features of your window frame, such as beveled edges or unusual angles. This ensures the new window perfectly matches your existing structure.
Select the Right Materials
Consider the materials used for your replacement windows or shutters. Different materials offer varying levels of durability, maintenance, and insulation. Consult with the manufacturer to choose the best material for your needs, taking into account your local climate and personal preferences.
Understanding Manufacturer Standards
Every manufacturer might have slightly different standards for producing and sizing windows. Familiarize yourself with these to ensure you are providing the correct measurements according to their guidelines.