How to Measure a Skylight for Replacement
To upgrade to new skylights, it’s important to have accurate measurements of your existing skylights. Knowing the size of your current skylights will help you determine what size your new skylights need to be in order to minimize the amount of additional cutting or reframing required for installation.
Check For Model Information
The easiest way to determine the size of a replacement skylight is to check the model number on your existing skylights. VELUX is the largest manufacturer of skylights so chances are pretty good that you have a VELUX skylight installed in your home.
Locate the Product ID Tag
Finding the product ID tag on your skylight is the first step in determining the correct replacement or compatible parts. The information on this label tells you the exact model and size of the skylight, which ensures you order the right product the first time.
- Locate the product ID tag on your skylights. For deck mounted skylights the tag will be on the interior of the skylight. For curb mounted models the tag will be found on the exterior.
- The first set of letters is your model, the next set of identifiers in the sequence contain your model size.
- Once you’ve identified all models and model sizes needed, place your order!
If the label is difficult to read or located in a hard-to-reach area, a quick photo with your phone can make it easier to review the details later. Having the correct model and size ready will help ensure a smooth ordering process and the best fit for your replacement skylight.
Interior and Exterior Measurements
Both external and internal measurements are required for a perfect fit. For the external measurements, start on the roof and measure along the side of the skylight where the shingles meet the flashing, noting the width and length. Then, measure the height of your skylight or curb. For the internal measurements, measure the width and length of the drywall around the skylight’s opening. Record all of these measurements to ensure that your new skylights will fit perfectly. If you’re not hiring a contractor or roofer to do the installation, you can use these measurements to order your replacement skylights.
Measure to Replace Deck Mounted Skylights
To begin, measure the exterior length of the glass and then the width of the glass from the interior of the cladding. Accuracy is crucial because new skylight models come with various drywall grooves.
These variations may necessitate trimming the drywall panel or filling any gaps with molding or painter’s caulk.
Additionally, for non-VELUX deck-mounted skylights, you must measure the length and width of the drywall opening inside the house and the entire skylight, including the cladding.
How to Measure Curb Mount Skylights
Similar to skylights that are mounted on the deck, when measuring the width of the exterior glass from the inside of the cladding, it’s important to also measure the outside length of the glass. However, in this case, it’s crucial to make sure that your outside length measurements of the glass include the flashing.
Accurate measurements will make the replacement process much smoother and help ensure your new skylight fits securely on the existing curb. Watch one of our skylight pros demonstrate the proper way to measure a curb mounted skylight for replacement in this brief, informative video so you can follow along step by step.
Pro Tips
When replacing your skylight with a VELUX brand skylight, it’s required to install a VELUX Flashing Kit in order to qualify for the VELUX 10-Year Installation Warranty. The flashing kit is designed to work specifically with VELUX skylights, helping ensure a proper fit and long-lasting, weather-tight seal. Using the correct flashing components helps protect your roof system and gives you added peace of mind that the installation meets VELUX warranty requirements. Check with your tax professional about potential solar tax credit eligibility and whether your new skylight may qualify.