How to Install a Skylight

A slate gray shingle roof with three skylights lined up in a row

Skylights can be an excellent addition to your home, adding immense amounts of light and the feeling of more space. A well-placed skylight that's adequately sealed can be a welcomed feature. Here is a step-by-step guide for installing a skylight yourself!

Wood framing of three skylights from the inside of the attic

1. Frame Your Opening

This is the only step you'll take from inside your home or attic. Frame the opening by doubling the rafters. Nail a doubleheader and sill to the top and bottom of the in the respective location. Drive a screw through the roof at each corner of your opening to serve as a marker for the outside of the roof.

A man using a circular saw to cut through the rooftop of a residential home

2. Cut the Opening for the Skylight

To remove the shingles, add 7 inches beyond the markings from the screws on all sides. Make chalk lines based off of your screw points, then cut out the frame through all layers of the roof with a circular saw.

Note: This is strictly a two-person job. The person on the roof must be on it securely. Use best safety practices to avoid falls or injuries. Have the other person inside the attic or home, ready to receive the cutout as you saw through the opening.

3. Install Flashing Around the Cutout

Install a self-adhesive membrane on the bottom edge of the opening. Cut and fold a one-inch overlap onto the exposed area of the sill.

An isolated image of a skylight with a brown frame

4. Install the Skylight

Raise the skylight through the cutout. Place the bottom edge onto the sill first, followed by the rest of the skylight. Drive galvanized roofing nails through the flange nail holes, to secure the skylight into place.

A skylight framing kit. Used to seal up all sides of a recently installed skylight

5. Seal Up the Sides

Once your skylight is firmly in place, you'll need to seal all sides. Beginning with the bottom flange, place a membrane strip that extends 6 inches on either side over the flange. Cut the edges of the piece on both sides at a 45-degree angle. Wrap the skylight frame with the top corner of the cut strip.

Repeat this step on both sides of the skylight. Then do the same on the top flange of the skylight. Cover the bottom membrane with roofing shingles, and nail them down securely.

Attaching flashing to the bottom of a newly installed skylight on a shingled rooftop

6. Install Bottom Sill Flashing

Place a bottom sill flashing over the shingles. Cover the bottom end of the skylight. Nail the flashing to the roof. Cover all exposed sides of the flashing with shingles.

An L-shaped piece of silver flashing, used to help seal and cover up the shingles at the bottom of the skylight

7. Install Side Flashing and Counter Flashing

Alternate installation of flashing pieces and shingles. Start by covering the shingles at the bottom of the skylight with an L-shaped piece of flashing. Cover L-shaped flashing with shingles. Install another piece of straight flashing higher up on the skylight, overlapping the shingles. Repeat on the other side. After the flashing has been installed on both sides, install counterflashing. Counterflashing snaps right on the rim of the skylight and seals out wind-driven rain and snow.

A professional installing saddle flashing on the top of a newly installed skylight

8. Install Saddle Flashing on the Top of the Skylight

Slide the upper portion of the saddle flashing under the first row of shingles and underlayment. Cut a slit in the underlayment to secure in place. Nail the flashing down. Cover all but four inches of the flashing with shingles.

Article Author

Adrian Brito

Frazier Roofing and Guttering in Arlington, TX is serving all of Tarrant County and surrounding cities. Durable roof and gutter supports the safety and comfort of your home.