Installing a tubular skylight
Installing a tubular skylight brings light into hallways, bathrooms or other interior rooms and is relatively inexpensive and simple. Different tubular skylights products provide different options, but the components are basically the same: a clear acrylic dome, roof flashing, flexible or rigid tubing and ceiling trim. Typical sizes are 10-, 14-, 18- and 21-inches in diameter.
A tubular skylight can bring a lot of natural daylight to dark, enclosed interior spaces. They are popular in hallways, bathrooms, walk-in closets and other rooms with no windows.
Some options and extras that are available on a tubular skylight include integrated vents, in-tube bulbs that turn the skylight into a conventional light at night and electronic dimmers that can block the light when it’s not wanted. Some models qualify for federal tax credits.
The following steps for installing a tubular skylight apply to a typical 10- to 14-inch diameter skylight. This popular size fits between standard framing members and doesn’t require cutting floor joists or roof rafters. Other models may require cutting of framing members and fashioning headers, and more specific instructions are included with those units.
The roof dome/flashing kit for a tubular skylight installs much like other roof penetrations such as vent stack flashing boots.
Step 1
Before installing a tubular skylight, choose a location and find the ceiling joist. Pick a spot on the ceiling that will provide the most light to the interior area but does not fall directly under an attic ceiling joist.
Make a small hole in the ceiling and stick a long piece of wire (about 12 inches or so) up through the hole. Go into the attic and find the wire. If the wire isn’t directly between the ceiling joists, you’ll have to relocate it.
The tube for the skylight must have adequate space between the joists. Clear away any installed insulation and adjust the position of the hole, if necessary.
Installation is fast and simple, with holes cut in the ceiling and roof and a reflective tube connecting the sealed roof flashing with the ceiling diffuser and trim ring.
Step 2
Find the most direct route to the roof. The distance between roof dome and diffuser usually should not exceed 10 feet, although some models allow for up to 14 feet.
A shorter, straighter tube works better, and if you have a choice, pick a southern exposure for the roof dome. Drill a small hole through the roof. Center the hole between two rafters and insert a wire so you can find the spot when you go up on the roof.
Step 3
Mark the cut line on the ceiling. Use the diffuser frame or a template provided by the manufacturer to mark the hole, making sure the template or frame is centered over the locator hole you made in the ceiling. Cut the hole for the tubular skylight, using a drywall saw to cut inside the line you marked and remove that section of the ceiling. Save the round cutout to use as a template on the roof when you’re ready to make that cut.
The diffuser and trim ring provide soft natural light and a finished appearance on the interior.
Step 4
Install the bottom tube assembly. Insert the assembly up through the hole and secure it according to the skylight manufacturer’s instructions. You will install the rest of the skylight tunnel from the attic after you have completed the roof cutout.
Step 5
On the roof, find the locator hole, center the ceiling cutout over it, and mark the roofing. Cut the roofing as carefully and cleanly as you can so you won’t have to replace any shingles. Once the roofing is cut, use a reciprocating saw or jigsaw to cut the roof decking inside the circle.
Many manufacturers offer options to customize tubular skylights. Options may include in-tube bulbs, electric dimmers or vents.
Step 6
Pry nails from the shingles directly above and beside the hole. Slide the roof dome’s flashing collar up under the top and side shingles, and over the bottom shingles, much like a roof vent flashing boot.
Secure and caulk the flashing, following the manufacturer’s instructions for proper fastening and sealing. Various roofing materials such as tile may require special flashing collars.
Tubular skylights can be installed on nearly any roof type, although custom flashing kits may have to be specified for some types of roofing.
Step 7
Make the connections in the attic. The ceiling opening does not need to be directly below the roof opening, as the tunnels are adjustable.
Connect the tube to the ceiling collar section and extend it to the roof opening. Cut it to fit and connect it to the roof opening. Here too, follow the manufacturer’s installation instructions for cutting and fastening the tube.
Step 8
Tape all joints and seams in the tubing. Replace the insulation between the joists. Place the diffuser lens into the trim ring. Snap the ring into the ceiling frame.
−By Rob Fanjoy
