Canadian Woodworking

Install a sun tunnel

Author: Allan Britnell
Photos: VELUX
Published: April May 2021

Installing a sun tunnel to bring natural light into an interior room or closet is easier than you think, and adds natural light to an otherwise dark area.



A sun tunnel, also known as a tubular skylight, is an affordable, relatively easy-to-install means of bringing natural light into a room or closet that doesn’t have any windows. Essentially, rather than having to go through the hassle and expense of building a light shaft for a traditional skylight, you simply cut small holes in the ceiling and roof, then connect the two with a metal tube.

At its most basic, a sun tunnel consists of an acrylic dome or flat glass cover that attaches to a roof-mounted flashing kit. Flashing kits are available for low to steeply pitched roofs. (Sun tunnels are not recommended for flat roofs.) A sheet metal tube – and any elbows required for angling around obstacles – that make up the tunnel slide into place through the flashing kit once it’s installed. The bottom of the tube then attaches to a diffuser mounted in the ceiling that casts the light around the room.

Some manufacturers also have energy-efficiency kits that install within the tunnel, and integrated electric kits so you can use the tunnel as a ceiling light after dark.

Probably the most challenging aspect of this job is that you have to do part of it on the roof. Unless you have a very low-pitched roof you should use a fall-arrest harness when working at heights. Granted, that’s not a tool most of us have laying around, but you can rent them.

This article will give you the broad outline of the key steps involved, but you’ll definitely want to follow the instructions that come with the model you bought for product-specific features. You do read instructions, don’t you?!

The job requires a few basic tools, plus a hole saw to cut through the ceiling (assuming it’s drywall) and a reciprocating saw or jigsaw to cut through the roof.

Cross Section
This mocked-up cross section of a typical sun tunnel shows the dome and flashing above a shingled roof, the sheet metal tunnel extending between the roof and the ceiling, as well as the diffuser at the bottom of the assembly.

Before and After
Once you get some natural light into an otherwise dark area of your home, the difference is stark. This walk-in closet is a great example of what a bit of sunlight can do for a situation.

Small or Dark
Rooms that are small or dark are a great option for a sun tunnel. Bathrooms, closets and hallways are obvious choices. Adding a sun tunnel to these areas will provide natural light year-round.

Main Areas, Too
Areas of your home that get used a lot, such as kitchens and family rooms, are also great options for a sun tunnel. Even though they may not be dark, more natural sunlight in these areas of your home will only make them more functional, bright and welcoming.

All Finished
A properly installed sun tunnel will keep the rain, snow and sleet out, and not be an eyesore. Depending on the distance between the roof and ceiling, you may need to cut the tunnel section to fit, or use multiple tunnel pieces to bridge the gap. Once your tunnel is assembled and cut to length (again, following the manufacturer’s specific instruc­tions), slide the tube down through the opening in the flashing. Note that the tube components are covered in a protective film. Do not remove this until immediately before installation. If exposed to the sun uncovered, the sheet metal can become hot enough to burn you.

Planning process

Step one involves getting up into the attic to see if there are any obstacles preventing you from installing a sun tunnel – you defi­nitely don’t want to be cutting into roof trusses, for example. Once you’ve confirmed you have a relatively clear path, take a rough measurement from the top of the ceiling to the underside of the roofing so you know what length of tunnel to order.

Note that you should always wear protective gear when working around attic insulation, including long sleeves, gloves and a dust mask.

Back on the ground, do your comparison shopping of the vari­ous makes and models available. Velux, Solatube and Columbia Skylights are the big names on the market with each offering a variety of lengths and diameters of the opening. The larger the diameter, the more light you get.

Two main types

There are two basic types of tunnels – rigid and flexible. A highly reflective rigid tunnel will bring in more light through a straight run from roof to ceiling, but you might need to use some elbows to work your way around obstacles in the attic. A flexible tunnel makes it easier to work around obstacles but will draw less light to the room.

The standard flashing kit that comes with a sun tunnel is designed to work with asphalt shingles or cedar shakes. There are also flashing kits available for use on tile roofs. If you have a steel roof or some other covering, contact the skylight manufacturer to see if their models are compatible with your roofing material.

Opening up

Start inside the room that you’re trying to illuminate. Find the location where you’d like it to go – ideally, in the centre of the room – and drive a nail through the ceiling into the attic. Get back up in the attic and move the insulation out of the way to find your nail. Once you’ve located it, run a string from the roof deck directly to the nail. If you have an unobstructed line, drive a nail through the roof deck to the outside. If there are any obstacles in the way (wiring, ductwork, etc.) adjust your location, or plan on using elbows or a flexible tunnel to get around those.

Before you start making holes, get up on the deck to find your marker nail. You want to install your tunnel at least a couple of feet away from any valleys or ridges to avoid leaks. If you’re too close, you’ll have to adjust the location. (Don’t forget to seal the nail hole you just made in the shingles.)

Once you’re satisfied with the location, it’s time to make some holes. Start by opening up the ceiling. Use a scribe to mark the hole for the ceiling ring, or centre the ring over your marker nail and trace around the outer diameter. Use a hole saw to cut out the opening.

The specific connection steps will vary slightly by manufac­turer so follow the steps in your installation manual here. Install and secure the ceiling ring for now, and then cover or plug the hole to prevent any debris from cutting the roof opening from falling into the house.

Back up on the roof, centre the flashing kit over your marker nail, then trace the outline of the opening. Use a flat pry bar to loosen two or three courses of shingles above the flashing kit, then use your jigsaw or recip saw to cut out the opening, removing the shingles and roof decking. As you finish, use your marker nail as a handle to hold on to so the cutout doesn’t fall into the attic.

Lift the edges of the remaining shingles and apply roofing mastic between the shingles and the roof, then slide the flashing in place under the shingles. Screw the flashing to the roof deck and seal the screwheads to prevent leaks. Lay the shingles back down over the flashing.

The final steps involve connecting the tunnel to the ceiling ring, sealing all the joints with tape, redistribut­ing the insulation, and connecting the interior light diffuser to the installed tunnel.

Now, sit back and bask in the – literal – glow of your latest successful DIY project.

Allan Britnell - [email protected]

A long-time freelance contributor to Canadian Woodworking, Allan Britnell is now the Editor-in-Chief of


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  2. Great! Unfortunately, we live in an area that mandates metal roofing for maximum protection. I have never seen one of these installed on this type of roof, so wonder if there is a recommended procedure.

  3. How about heat loss. The tunnel is uninsulated. Would it not be prudent to insulate the tunnel from the roof to the attic floor? Is the heat loss outweighed by the additional interior light?

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