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Measuring Arched Windows and Skylights for Replacement
Arched windows and skylights have architectural appeal and light up interior spaces. A sagging arched window is a sure sign that you need to replace it. When the skylight leaks or you’re getting your roof replaced, it’s time to replace the skylights.
Before replacing arched windows or skylights, you’ll need to take accurate measurements to ensure you buy the right replacement windows. This can be a do-it-yourself-friendly project if you’re comfortable working on a ladder or on the roof. If not, contact a Lowe’s associate for help with your project.
How to Measure Arched Windows
Measuring for arched windows is easy to do. To find the base width, measure at the bottom of the arch from corner to corner inside the window opening. To find the window’s height, measure from the bottom to the tallest point inside the window opening. To find the depth, measure from the front windowsill back to the trim. There should be at least 3 1/4 inches of opening depth.
The perfect arch is when the height equals exactly half of the width. Once you have your measurements, or if your window isn’t a perfect arch, speak with a Lowe’s associate for assistance selecting a replacement skylight that’s the correct size.
How to Measure Skylights for Replacement
When replacing your skylights, you’ll need to take two sets of measurements. Take your first set of measurements outside on the roof.
Curb-mounted skylights sit inside a built-up box, or curb. For curb-mounted skylights, measure the width of the window from one side of the existing curb to the other, including any material that’s been applied to the surface of the curb, such as flashing. Next, use the same parameters to measure the height.
Deck-mounted skylights are mounted directly to the roof. Measure the exterior glass pane width and length from the inside edge of the cladding — the exterior aluminum protective layer — and the overall width and length of the skylight.
Now, you’ll need to go inside to measure the interior drywall width and length around the skylight opening. Measure the width and height in several spots to ensure you have the correct dimensions.
These instructions on how to measure for a skylight should help you get the right measurements for replacement.
If you plan to work on the roof, remember safety comes first. Use a fall-protection system with equipment that includes roof anchors, a harness, lanyard, and lifeline. Be sure to follow all manufacturer’s instructions for use and safety. Whenever using a ladder, always have another person hold it, and climb and descend with caution. Face the ladder and have two hands and one foot or one hand and two feet on the ladder at all times.
If you’re not comfortable working on the roof, contact a Lowe’s associate to help with your project.
Make sure you choose the right ladder for the job. See our helpful resource: Types of Ladders Buying Guide.
Tips for Measuring Arched Windows and Skylights
- Always follow the width-by-height formula and make sure to record the measurements so you can refer to them later.
- When following these steps on how to measure arched windows, use a steel tape measure. It can help you get accurate measurements.
- If you have more than one arched window or skylight, take measurements for each individually. Don’t rely on the measurements of one window to represent measurements for all windows.
- If you’re working with a contractor, take pictures of the tape measure that shows each measurement.