Conventional skylights typically consist of two panes of window glass mounted in a wooden frame, while tubular skylights capture daylight through a small, durable plastic lens mounted on the roof. Light is directed down a reflective tubular shaft—ranging in diameter from about eight to twenty-four inches—to a diffuser mounted on the ceiling in the interior space. The shaft’s polished aluminum interior ensures maximum light transmission and provides a high level of illumination, even on cloudy days. The diffuser, which looks a lot like a ceiling light fixture, enables light entering the room to disperse naturally over a wide area. In larger rooms, several tubular skylights can be used to provide uniform lighting.
Tubular skylights virtually eliminate unwanted heat gain in summer months—a common problem with conventional skylights whose large glass surfaces allow enormous amounts of sunlight into our homes. In winter, tubes provide natural light during daylight hours while permitting little heat loss during evening hours or on cold, cloudy days—another common problem of the conventional design.
Ease of installation is another advantage. A conventional skylight requires a day or so to install in an existing home and requires creating a large opening in the roof and ceiling. Often, this involves cutting through framing members and modifying existing framing to maintain structural integrity. In addition, a light shaft must be constructed to transmit light from the skylight into the house. And finally, you have to repair the damaged ceiling and roof, apply drywall to the light shaft, and repaint.
In contrast, installing a tubular skylight requires only two small circular holes—one in the ceiling and one in the roof—between existing framing members, so there’s no need to mess with the framing. The lens and shaft and diffuser lens are snapped in place and secured to the roof and ceiling, which takes a couple of hours. To make things easier, many manufacturers provide installation kits that include all the parts you need. To minimize ceiling penetrations, several tubular brands offer supplementary electrical lights for use at night. Moreover, because they’re compact and energy efficient, tubular styles can be installed in places where it would be difficult to install a conventional skylight, such as narrow hallways or walk-in closets.
A tubular skylight can save you money; however, the potential economic savings depends on initial and installation costs and how much electrical lighting it will displace. Most models retail in the $200 to $500 range, depending on unit size and manufacturer. Installation by a professional could easily run $200 or more—depending on the job difficulty. On a sunny day, the DayLite eight-inch tubular skylight provides the same amount of light as seven 100-watt light bulbs. DayLite’s twelve-inch size provides the equivalent of ten 100-watt light bulbs. Even on cloudy days, these skylights provide 100 to 180 watts of illumination.
However, not all installations save substantial sums; in fact, it could take a number of years to pay back your initial investment. But if you’re going to install a skylight anyway, you’re better off installing a tubular one.
Installation Intelligence: Before You Install