Buy the Extreme How-To Book

How-To Install a Tubular Skylight or Light Tunnel

Construction How-To, Lighting, Windows & Doors September 20, 2006 Sonia



By Monte Burch

 

Tubular skylights bring natural light indoors.

 

 

 

 

Roof mounted skylights have been used for many years to bring the sun into our buildings, and a wide range of skylights are available. These days, tubular skylights can capture more sun than traditional skylights, even for small areas, and also provide more versatility. These units are also a basic do-it-yourself project and are available in a wide range of sizes and brands, such as Velux, Solatube, Sun-Dome, Sun Pipe and Sun-Tek.

While many skylights are more complicated, you can install a sun tube, such as the Sun-Tek Sun Tube shown in this article, in less than an afternoon. Instructions and everything you need come with the kit, including special leak-proof roof sealant. Sun-Tek’s tubes consist of three parts, a sun-dome for the roof, a tube to channel the light, and a diffusing system to disperse the light evenly.

As many have discovered, a simple skylight is often not the answer. It can provide light, but the light intensity changes with the amount and direction of the sun. You can have a “hotspot” of light on bright sunny days. Sun tubes eliminate this problem, providing evenly dispersed light throughout the area. And, they can also be used to direct light down through an attic and into a small area, such as a narrow hallway, even a dressing closet. They can also be used to provide natural light in a bathroom, and still maintain privacy.

The first step in installation is to mark the opening for the cut-out. Measure carefully, making sure the opening is square, then drive screws up through the roof sheathing and shingles at each corner of the opening.

The first step in installation is to mark the opening for the cut-out. Measure carefully, making sure the opening is square, then drive screws up through the roof sheathing and shingles at each corner of the opening.

 

A Close Look at the Tube

The Sun-Tek’s tubular skylights are available as single units, with tube sizes of 10, 14 and 21 inches and with tube length ranging from 10 to 30 feet, depending on the unit chosen. They can illuminate an area of 150 to 450 square feet. The one-piece seamless construction of the tube creates a completely leak-proof unit, and the exterior dome is made of super-tough polycarbonate that is impervious to hail and tree branches. The dome blocks 99-percent of damaging UV rays, so it is easy on carpeting and furniture. The tube is made of reflective aluminum to enhance reflectivity. Each unit comes with two elbows (15 inches in length when straightened) and one straight piece. Straight connectors are 22 inches long. In most instances additional straight connectors are needed. Also included in each kit is the diffuser lens, one tube of STS 1000 Sun-Tek butyl sealant, 10 yards of generic duct tape, and a galvanized steel (22-inch gauge) roof collar that can be used by the homeowner in the event they cut the roof opening too large. Extension connectors are available, as well as light kits that allow you to use the units for night-time lighting.

The company also offers multiple-tube units, called Sun-Tek Spyder Systems, which are available with two or four tubes and a single dome skylight. These are more complicated to layout and design, as well as to install. However, they do allow for much more dispersal of light by spreading out the tubes and diffuser. For instance the Model Quad 10-inch provides four tubes, each with light capabilities of 150 square feet.

We chose a Model Quad 10-inch, Spyder System for installation in a woodworking shop. The installation is somewhat different, in that the shop ceiling had not yet been installed. This not only made it easier to install the skylight, but permitted easier photography. We installed a Curb Mount Aluminum Skylight which required construction of a curb, as well as standard roof-flashing steps. Self-flashing models are also available.

A sun port with four tubes fits over the curb. It's a good idea to make sure it fits before you install the curb on the roof.

A sun port with four tubes fits over the curb. It's a good idea to make sure it fits before you install the curb on the roof.

A 2x4 or 2x6 "curb" or frame is then contructed for the skylight. It should fit with its inside edges flush with the opening. Treated lumber, waterproof glue and deck screws were used for this assembly.

A 2x4 or 2x6 "curb" or frame is then constructed for the skylight. It should fit with its inside edges flush with the opening. Treated lumber, waterproof glue and deck screws were used for this assembly.

 

The curb must be flashed into the shingles. You can make some of the flashing pieces before you get onto the roof.

The curb must be flashed into the shingles. You can make some of the flashing pieces before you get onto the roof.

A skylight dome fits over the port and curb. Again, it's important to check for fit.

A skylight dome fits over the port and curb. Again, it's important to check for fit.

 

Installation

The model we choose requires a 22-1/2-by-22-1/2-inch cutout, which allowed it to fit between our 24-inch spaced roof trusses. First step in this type of installation is to determine the location of the skylight as well as the tube lenses. Then mark the location of the cutout and drive wood screws up through the roof and asphalt shingles from the inside or underside of the roof. Up on the roof; use the protruding screws and a chalk line to outline the cut-out. Then make the cut-out with a reciprocating saw.

Then cut along the chalk line through the shingles and roof sheathing.

Then cut along the chalk line through the shingles and roof sheathing.

On the roof, snap a chalk line between the protruding screws to mark the outline of the cut-out.

On the roof, snap a chalk line between the protruding screws to mark the outline of the cut-out.

 

We used pressure-treated 2-by-4’s for construction of the curb. It’s a good idea to construct the curb, and then test the sun port and skylight for fit before installing it on the roof. The curb is made to fit with its inside edges flush with the cut-out. Place the curb over the cut-out and mark around the outside edges. Then remove the shingles down to the roofing felt using a sharp utility or roofer’s knife.

For the installation shown, on-site flashing is added. This begins with a flashing along the bottom edge, a piece of flashing placed under each shingle and lapping up the sides, then a top flashing. Flashing must be anchored to the curb with roofing nails, and the entire assembly must be well caulked with a good roofing sealant.

Using the Sun-Tek STS 1000 Sky Light sealant, run a bead around the location of the curb.

Using the Sun-Tek STS 1000 Sky Light sealant, run a bead around the location of the curb.

Lay the assembled curb on the opening and cut all around the outside edge through the shingles and down to -- but not through -- the roofing felt. Remove all shingles in the area of the curb.

Lay the assembled curb on the opening and cut all around the outside edge through the shingles and down to -- but not through -- the roofing felt. Remove all shingles in the area of the curb.

The next step is to flash the curb and shingles. This can be hand-cut flashing, or a flashing kit available from Sun-Tek. Flashing must be well sealed with sealant.

The next step is to flash the curb and shingles. This can be hand-cut flashing, or a flashing kit available from Sun-Tek. Flashing must be well sealed with sealant.

Then fasten the curb in place using the screws provided (driven at an angle, or from beneath). I used 3-1/2" deck screws I had on hand, driven down from the top.

Then fasten the curb in place using the screws provided (driven at an angle, or from beneath). I used 3-1/2" deck screws I had on hand, driven down from the top.

 

The sun port is installed and fastened in place with nails or screws.

The sun port is installed and fastened in place with nails or screws.

The sealant supplied with the kit is then applied to the top of the curb.

The sealant supplied with the kit is then applied to the top of the curb.

 

Then the dome is positioned and fastened with screws to the curb.

Then the dome is positioned and fastened with screws to the curb.

Sealant is applied to the top edge of the sun port.

Sealant is applied to the top edge of the sun port.

 

Place a bead of roof sealant on the upper edges of the curb and fit the sun port down over it, then fasten in place with roofing nails. Place another bead of caulk over the outer edge of the sun-port and place the skylight down over it. Then fasten the skylight in place with screws provided through the holes in the sides and into the curb.

Back off the roof and in the attic, position the sun tubes in place. Pieces of duct tape can be used to hold them temporarily together until you get them arranged as desired. Then mark locations for the ceiling holes and cut them. Once you have the tubes arranged to meet the holes, fasten the tubes, elbows and sunport drops together using the sheet metal screws provided. Then wrap with the duct tape provided. Final step is to install the diffuser lenses.

Capturing the sun is fun and easy with the tubular skylight systems. You can easily install them yourself to bring in the sun and brighten your home interior anywhere you please.

The tubes, elbows and extensions are held together with self-starting screws (provided).

The tubes, elbows and extensions are held together with self-starting screws (provided).

In the attic the tube extensions and/or elbows are assembled to the sun port.

In the attic the tube extensions and/or elbows are assembled to the sun port.

 

The bottom lens sections are then positioned in place. They are held with straps anchored to the rafters, as well as screws and tape.

The bottom lens sections are then positioned in place. They are held with straps anchored to the rafters, as well as screws and tape.

Then duct tape is wrapped around the joints.

Then duct tape is wrapped around the joints.

 

The final step is to snap the lens in place. In most cases this would be after the ceiling has been installed, or after a hole has been cut in the ceiling.

The final step is to snap the lens in place. In most cases this would be after the ceiling has been installed, or after a hole has been cut in the ceiling.

 

Tubular Skylight Resources

Solatube
www.skylightsusa.com, 1- 800-346-6991

Sun-Dome
www.solardev.com, 561-842-8935

Sun-Tek
www.sun-tek.com, 407-859-2117

Sun Pipe
www.sunpipe.com, 1-800-844-4786

Velux
www.millworkforless.com, 1-866-645-8885