How to Fit a Skylight Window

Updated July 20, 2017

If you want more natural light to come into your home, putting up skylights is a great design option. Skylights are often used in atriums and temples. But they have also been used in a lot of homes as an elegant and practical design choice that adds a grand look to the home as well as allowing natural light to come in. Modern skylights are usually covered with a special skylight window. If you want to give your home a bright interior, you may want to learn how to properly fit a skylight window.

Measure the area on your ceiling or sloped wall where you want to install a skylight window. Check the rafters of your roof. The best way to fit and install a skylight is exactly between two roof rafters.

Mark the area where you are going to install the skylight window. It is best to mark from the middle point between two roof rafters. Use a pencil, measuring tape and ruler. Measure the dimensions of the window. Subtract a half-inch from the dimensions that you took and use this measurement for the opening of the window. Sometimes the manual that came with the skylight window suggests what exact dimension to cut based on the size and shape of the skylight.

Cut through the measurements you made on the drywall ceiling using a circular saw.

Frame the opening for the window skylight with wood boards. Follow the instructions in the manual on how to frame the window. Make sure the boards that you use are as wide as the existing roof framing. The thickness, however, depends on the window itself.

Go up to the roof and cut a hole through the roof in the same hole that you cut the drywall ceiling. Use nails as indicators and guidelines for cutting. Cut through the roof shingles with a circular saw. Make sure that your cut is straight.

Hold the skylight window against the board frame to see how it fits into the opening.

Place the window skylight in the opening temporarily. Ask a friend to hold the window as you secure the window. Then check whether the window is aligned with the opening on the ceiling drywall and the opening on the roof. The corner angles should each be 90 degrees. Use a level to check the horizontal edges of the skylight.

Secure the skylight window into the opening using screws. Follow the specific instructions in the skylight window manual on how to secure the window into place.


Cover the floor beneath the skylight to protect it from drywall pieces and dust.


Be extremely careful when working while standing on a ladder.

Things You'll Need

  • Measuring tape
  • Pencil
  • Ruler
  • Circular saw
  • Wood boards
  • Nails
  • Level
  • Screws
  • Drill
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About the Author

Based in New Jersey, Michelle Raphael has been writing computer and technology articles since 1997. Her work has appeared in “Mac World” magazine and “PC Connections” magazine. Raphael received the George M. Lilly Literary Award in 2000. She holds a Bachelor of Arts in political science from California State University.