Component
What Is a Tubular Skylight? Function and Role in Roofing Systems
Also called: sun tunnel, solar tube, light tube, tubular daylighting device
Tubular Skylight is a cylindrical daylighting device installed through a roof, consisting of a reflective tube that channels natural light from a rooftop dome to an interior ceiling diffuser.
In plain English
A tubular skylight is a roof component consisting of a small, cylindrical structure that channels natural daylight from the roof through a reflective tube to interior spaces, typically terminating with a ceiling diffuser to distribute light within the building.
How tubular skylight works
A Tubular Skylight is a daylighting device designed to channel natural sunlight from the roof into interior spaces using a highly reflective, cylindrical tube. Structurally, it consists of three main components: a weather-sealed dome mounted on the roof—typically at or near the ridge or along a roof slope—an internally reflective tube that traverses the attic or roof cavity, and a diffusing lens installed at the ceiling level. The geometry of the tube, usually ranging from 10 to 22 inches in diameter, allows it to fit between rafters and trusses without significant alteration to the roof’s structural integrity or usable attic space.
Functionally, a Tubular Skylight captures sunlight through its rooftop dome, even at low sun angles, and transmits it efficiently down the tube via specular reflection. The ceiling diffuser then disperses the light evenly, reducing glare and providing consistent illumination. This system is engineered to maintain the roof’s water drainage and snow shedding capabilities, as the dome is sealed to prevent leaks and withstand wind uplift. Tubular Skylights are commonly used in areas where traditional skylights are impractical due to roof pitch, limited space between rafters, or the need to minimize heat gain and loss, making them suitable for both low- and steep-slope roofs.
Benefits
NATURAL DAYLIGHTING
Tubular skylights channel sunlight into interior spaces, reducing reliance on artificial lighting and enhancing occupant comfort.
ENERGY EFFICIENCY
By increasing natural light penetration, tubular skylights help lower electrical lighting loads and contribute to overall building energy savings.
LEAKAGE PREVENTION
Properly integrated tubular skylights feature sealed flashing systems that minimize water intrusion risks at roof penetrations.
SYSTEM INTEGRATION
Tubular skylights are designed to work with various roofing assemblies, maintaining roof integrity while providing targeted illumination.
Limitations
LEAKAGE AT SEALS
Tubular skylights are prone to water intrusion at roof and ceiling seals if flashing or gaskets are improperly installed.
CONDENSATION RISK
Improperly insulated or ventilated tubular skylights can accumulate internal condensation, leading to moisture damage in roof assemblies.
LIMITED STRUCTURAL LOAD
Tubular skylights cannot bear significant roof loads and may compromise structural integrity if installed in load-bearing areas.
DEPENDENCY ON ROOF PITCH
Performance and watertightness of tubular skylights are highly sensitive to roof slope, with low-slope roofs increasing leak risk.
Common problems
SEAL FAILURE LEAKS
Failed seals at the tubular skylight flashing can allow water intrusion, leading to roof leaks and interior moisture damage.
CONDENSATION ACCUMULATION
Improperly insulated tubular skylights can accumulate condensation inside the tube, causing water staining and potential mold growth.
FLASHING CORROSION
Metal flashing components of tubular skylights are susceptible to corrosion, especially in coastal or high-humidity environments.
DIFFUSER CRACKING
UV exposure and thermal cycling can cause the interior diffuser of a tubular skylight to crack, reducing light transmission and compromising weather resistance.
Where you'll see it
DAYLIGHTING INTERIOR SPACES
Tubular skylights are installed to channel natural light into interior rooms where traditional skylights or windows are not feasible.
ENERGY EFFICIENCY UPGRADE
Tubular skylights are used to reduce reliance on electric lighting in hallways, bathrooms, or closets, improving building energy performance.
RETROFIT APPLICATIONS
Tubular skylights are selected for existing roofs where minimal structural modification is required to add daylighting.
LOW-LEAK RISK DESIGN
Tubular skylights are integrated into roofing systems to provide natural light with a smaller roof penetration, reducing potential leak points compared to larger skylights.
Don't confuse it with
- tubular skylight vs traditional skylight
- tubular skylight vs solar tube
- tubular skylight vs roof window
- tubular skylight vs vented skylight
Regional & climate notes
Most relevant in: All climates.
Frequently Asked Questions
What is a tubular skylight in roofing?
A tubular skylight is a roof component that uses a reflective tube to channel natural sunlight from the roof into interior spaces, providing daylight without significant heat gain or structural changes.
How does a tubular skylight work to bring natural light into a room?
A tubular skylight uses a rooftop dome to capture sunlight, channels it through a highly reflective tube, and diffuses the natural light into the room below, brightening interior spaces without electricity.
Why is a tubular skylight an important addition to a roofing system?
A tubular skylight is important because it channels natural daylight into interior spaces, reducing reliance on artificial lighting, improving energy efficiency, and enhancing indoor comfort without significant structural changes to the roofing system.
How does installing a tubular skylight affect a building’s energy efficiency and indoor comfort?
Installing a tubular skylight increases natural daylight, reducing reliance on electric lighting and lowering energy costs. Properly installed units minimize heat gain or loss, enhancing indoor comfort without significantly impacting heating or cooling efficiency.
How do you measure the light output of a tubular skylight for your specific room size?
To measure tubular skylight light output, check the manufacturer's lumen rating and compare it to your room's square footage; typically, 1,000–1,500 lumens adequately illuminate 100 square feet of space.
What factors influence the energy efficiency of a tubular skylight installation?
The energy efficiency of a tubular skylight depends on tube length, reflective material quality, roof and ceiling insulation, lens design, and proper sealing to prevent air leaks and minimize heat gain or loss.
Related terms
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