Replacement Installation Process

Fast, Easy Skylight Replacement

Replacing skylights when you reroof is a quick, easy way to increase your profits while providing a stronger, more cohesive roof system for your homeowners. Skylights older than 20 years old are susceptible to frame damage during the reroofing process, which can lead to leaks or other issues.

Skylight replacement can be broken down into three parts:
  1. Part One: Measure the existing skylights and order appropriately sized VELUX skylights for installation day.
  2. Part Two: Remove the existing skylights, any flashing or underlayment, and the surrounding shingles.
  3. Part Three: Fit the new flashing, underlayment, and skylights to the existing holes and attach them to the roof, then replace the surrounding shingles.

VELUX skylight installation

How to Identify a VELUX skylight

All VELUX skylights are installed with a product tag to identify them as ours. On deck-mounted skylights, the ID tag can be found on the inside of the frame. On curb-mounted models, the ID is stamped on the outside of the frame. If the tag is missing or inaccessible, a Velterm number located in the top right corner of the skylight’s space bar can provide identifying information.

On new tags like the one seen to the right, the code identifies the product details:

  1. Unit type
  2. Unit size
  3. Variant code
  4. Block number
  5. Manufacturing year
  6. Manufacturing month
  7. Manufacturing plant
For more details about these identifiers, download the Skylight Measurement Guide.
How To Identify a VELUX Skylight

How to Measure a Skylight

To replace a standard-sized, curb-mounted skylight:

  • Measure the width of the existing skylight’s outside curb
  • Use this measurement to determine your curb-mounted VELUX skylight replacement

To replace a deck-mounted skylight, measure the existing skylight’s:

  • Finished interior from drywall to drywall as close to the light shaft as possible. We recommend adding 1" or 1.25" overall to your interior finished drywall measurement.
  • Outside frame around the interior drywall
  • Exterior visible glass area

For a custom-sized, curb-mounted skylight, measure:

  • Outside dimensions of the curb (not the frame), including roofing and flashing material
  • Maximum skylight clearance (we require clearance dimensions in ¼" increments for length and width)

How To Measure a VELUX Skylight

How to Measure a Roof Pitch

Roof pitch is an important part of skylight installation because each VELUX skylight and flashing kit is engineered with specific pitch requirements. Correct roof pitch is essential for effectively draining water off the skylights.

Roof pitch is defined as the angle of the roof. It is calculated by the number of inches a roof rises vertically for every 12 inches it extends horizontally. To ensure an accurate reading, measure the roof pitch by placing a pitch gauge directly on the roof where the skylight will be installed.
VELUX - How to measure roof pitch