Posted by VELUX Skylights on July 20, 2024

How to Measure Your Existing Skylight for a Replacement


When it comes to skylight replacements, there are some things you need to know about your existing skylights before you can upgrade to shiny new ones. Namely: how big are your existing skylights? When you order your new skylights, what size will they need to be to replace your existing ones with the least amount of additional cutting or reframing?


Measuring Skylights for Replacements

In order for your skylight replacement to be a perfect fit, you'll need accurate measurements of your existing skylight. Your contractor or roofer will likely take measurements of their own, but if you're more the DIY type or you just want to know more about your skylight, here's how to measure your skylight for replacements.


You'll need numbers from both the outside and inside of the skylight. That means the first numbers will be found on the roof. Once you're up there, measure along the side of the skylight where the shingles meet the flashing, width first then length. Next, measure the height of your skylight or curb. Make a note of those numbers, then it's time to move inside for the rest of the measurements.


On the inside of your skylight, you're measuring the width and length of the drywall around the skylight's opening. Note these numbers as well.


Pro-Tip: When you're taking your measurements, snap a picture of your tape measurer showing the lengths, widths, and heights. Pass these along to your contractor or roofer to support the accuracy of your measurements.



All of these measurements will be used by your roofer or contractor to determine the size of your replacement skylights and ensure a perfect fit. Not sure if your skylights are ready for replacement? Talk one on one with a VELUX design expert through a free virtual consultation to determine if your skylights are ready for an upgrade.