However, before you start cutting holes, you want to check with your local building code to ensure you choose the right type of skylight to coordinate with ventilation and natural light requirements.
Prior to starting the process of installing your new skylight, you want to have the actual skylight with you along with the instructions from the manufacturer. This will provide you with the rough dimensions and specific steps for installation. To get started, the opening will need to be located and marked. With a saber or drywall saw, you will start by cutting out a two-foot square test hole in the ceiling where you want the center of the skylight to go.
Next, look around the ceiling and roof framing to determine the best place for the opening location and consider plumbing and electrical installations. Now you want to position and then mark the opening, which will help minimize the amount of framing and joists needing to be cut. Using the saw, you will cut the opening along the guideline. Remove the ceiling material and then install your temporary bracing. Then, you want to cut through the ceiling joists and framing according to the skylight opening.
To frame the opening, you will double the last uncut joist on either side of the ceiling opening and then install double headers going across the opening with the ends to the cut joists sitting perpendicular. Using lumber that is the same depth as the ceiling framing, you will nail the trimmer joists to the frame the same as the opening for the light shaft. With 12d nails, go through the metal framing ties to connect the joists securely. The next step involves locating and marking the roof opening. To do this, hang a plumb bob at the bottom edge of the roof rafters, going down to each corner of the opening in the ceiling. These corner locations will be transferred vertically to the rafters, taking these points to the underside of the roof, as a way of locating the rough opening that will be cut through the roof. Next, drive a pilot nail through the roof at each of the corners at your proposed opening. Keep in mind that you want the corners to fall within the skylight curb framing.Now the roof opening will need to be cut and framed. Typically, prefabricated skylights already have the curb assembly mounted. With this, you would take the assembly to the roof along with pilot nails that will be used as guides. If you have an asphalt-shingled roof, simply take a utility knife and cut along your marked lines, and then remove the shingles. Next, with a circular saw, you would cut through the sheathing. For wood-shingles, you will cut through the shingles and the roof together, placing a board beneath the board to allow the saw to glide freely. Remember to save the shingles for later. The roof opening will be framed by doubling the rafters at the sides of the roof opening, as well as the ends of the cut rafters. Now, install the double headers going across the opening at both ends.
To install your skylight, you would need to follow the manufacturer’s instructions, making sure it has been secured temporarily while you test the position. If the skylight is misaligned, not only would it be noticeable from the inside but it would also create risks for future leaks. With a level, you want to check the sill and then measure the diagonals to ensure the corners are square. Once done, the brackets will be screwed into the roof over a layer of building paper. To flash the curb and repair the roof, you will install an aluminum sill, head, and step flashing. Make sure you interweave the flashing and replacement shingles, as you move ahead. Then, apply roofing compound under the flashing and shingles. Finally, the shaft will be framed and the interior finished. You want the side of the shaft to be framed using 2×6s and then with an adjustable bevel gauge, mark, cut, and install the framing. The walls will now be insulated with R-19 fiberglass batts by stapling a 6-mil polyethylene vapor barrier on the inside sides. The shaft will be finished and then the joists taped with drywall tape and joint compound. Use 100-grit sandpaper or drywall sanding mesh to help smooth the joint compound and then apply the finish paint. The last step is to install wood molding, as a means of hiding the joint found between the drywall and skylight.