Determine the best location in the room for the skylight based on where you’d like the light to shine brightest in the room. Find the ceiling joists at that location by passing a stud finder over the ceiling. Adjust your desired skylight location to fall between two joists so that you won’t have to cut through them to create your framework.
Climb a ladder and then place the skylight body against the ceiling. Trace the outline of the skylight onto your ceiling with a pencil and the set the skylight aside.
Drill holes into the ceiling at the inside corners of the marks. Cut the traced line between the holes using a keyhole saw, leaving an opening in your ceiling for the bottom of the skylight well.
Remove the insulation covering the opening in your ceiling. If you home uses batting as insulation, then put on work gloves, a face mask and safety goggles to protect yourself from fiber strands and cut through the insulation with a utility knife before pulling it away.
Go into the attic or crawlspace above our ceiling. Locate the hole cut through the attic floor. Dangle a plumb bob from the underside of the roof over one of the corners along the bottom of the hole in the attic floor. When the plumb bob is directly over the hole, mark its location on the roof. Repeat the process for the second lower corner of your hole. Place the skylight onto the roof with its lower corners at the marks. If the width of the marks match the width of the skylight, then trace the skylight onto the bottom of the roof. If there is no match, then adjust the positioning of the marks using the plumb bob again until they match. Drill a hole through the roof at each of the inside corners of the drawn skylight.
Place a ladder against the side of your house near the skylight location. Climb the ladder to your roof and locate the four holes drilled from the attic. Remove all of the shingles or roofing tiles covering the area between holes, and then connect the holes with a chalk line to create the outline of the skylight. Use a staggered pattern for those shingles left around the opening to make replacement after the skylight installation easier. Snap chalk lines to mark the perimeter of your needed skylight opening.
Cut through the roofing felt and the roof sheathing along the snapped chalk line with a circular saw. Hold the edge of the sheathing before making the final cut to avoid dropping it through the new space.
Go back into the attic area. Frame the opening in the roof using two wooden planks the same size as those used for the roof trusses. If the roof uses 2-by-6-inch boards, then follow suit. Cut the planks with a circular saw to fit the opening between the rafters running on both sides of the skylight opening. Place the boards between the rafters at the head and base of the opening. You want to frame the opening with the boards, so do not allow the board edges to overlap the opening at all, keep them flush along the opening's edge and flat against the roof sheathing. Attach the boards to the rafters with 16d nails driven through the side of the rafters and into the ends of the boards.
Use the same framing process used on the roof to frame the hole in your attic floor. Use the same sized planks as those used for the ceiling rafters for your framing material, and avoid overlapping the hole with the frame.
Measure the angles of the joists and rafters with a T-bevel. Cut 2-by-4-inch planks to use as wall studs to join the corners of the two openings to create the framework the light shaft. Cut the ends of the 2-by-4s with the measured angles so that you can slide the studs into place between the frames. Nail a wall stud between each of the corresponding corners of the frames, using 8d nails to secure them into place.
Things You Will Need
- Wall stud finder
- Keyhole saw
- Work gloves
- Safety goggles
- Face mask
- Utility knife
- Plumb bob
- Chalk line
- 2-by-6-inch boards
- Circular saw
- 16d nails
- 2-by-4-inch boards
- 8d nails
- If you have to cut through a ceiling joist or rafter, first nail a 2-by-4 to the rafters or joists about 6 inches from the desired cuts to support the opening, then cut the rafter or joist with a reciprocating saw. After cutting, double the boards that you use to frame the openings, nailing them in place with the 16d nails, and then nailing the boards together with 8d nails.