Architects specifying commercial daylighting from above face a narrower set of decisions than the product landscape might suggest. The types of skylight available for commercial construction fall into two structural categories. The glazing choice within each category determines most of the long-term performance outcomes. Understanding both dimensions before the schematic phase keeps more options open and avoids costly substitutions later.
Types of Skylight in Commercial Design
Architects working on commercial projects encounter two main types of skylight: surface-mounted and self-spanning systems. Surface-mounted skylights attach to an existing roof structure and sit within the roof plane. Also, both system types accept either glass or polycarbonate glazing. Self-spanning skylights, by contrast, bridge an opening without a separate support frame. The choice between glazing materials shapes cost, weight, thermal performance, and long-term maintenance requirements.
The structural category shapes the installation approach; the glazing choice shapes everything else. Additionally, retrofit projects account for a significant share of commercial skylight work. Furthermore, many of those facilities were originally built without daylighting as a design priority. Also, building orientation, opening size, and daylighting goals all shape the decision. The Department of Energy’s skylight performance ratings guidance addresses each of those factors directly.
Why Glazing Choice Defines Performance
Not all types of skylight perform the same way over time, and the glazing material is the primary reason. Still, glass skylights offer high clarity and a premium appearance. However, they are heavy, costly to curve, and vulnerable to impact. Polycarbonate skylights, in contrast, are up to 250 times more impact-resistant than glass. They are also significantly lighter, which reduces the structural load on the roof and shortens the installation window.
Polycarbonate panels receive a UV-reflecting coextrusion on both sides during production. That prevents yellowing and extends the service life of the system. Multiwall polycarbonate also provides up to four times the insulating value of single-pane glass, reducing the thermal load on the roof assembly. For architects weighing glazing options, polycarbonate outperforms traditional glazing materials in terms of durability in most commercial conditions.
EXTECH SKYGARD®: Two Systems for Two Conditions
EXTECH offers two main types of skylight under the SKYGARD® line, and each addresses different structural conditions. Specifically, the SKYGARD 3300® is a surface-mounted skylight that sits on top of the existing roof structure. That makes it a strong fit for retrofit work where framing is already in place. Consequently, it is one of the more versatile surface-mounted options for commercial projects. The system also works in new construction, where a flush roofline is the design goal.
The SKYGARD 3700® is a self-spanning skylight that bridges large openings without a separate support structure. That makes it one of the few types of skylight suited to wide-bay industrial, athletic, and transit facilities. Polycarbonate diffuses light evenly across the interior, which controls glare directly.
The WBDG's daylighting resource identifies glare control as critical to successful skylight design. Both SKYGARD variants surpass AAMA standards for air infiltration, water resistance, and structural performance. For instance, EXTECH’s NYCTA skylight case study documents this directly. In the report, twenty-five SKYGARD 3700® units replaced failing skylights in an active transit maintenance facility. Also, both systems ship as prefabricated assemblies, so components arrive pre-cut and ready to install.
Choosing the Right Types of Skylight for Retrofit Projects
Retrofit work presents specific challenges for any skylight specification. The existing structure may not support the weight of a glass system. Also, access is often limited, and the construction window is short because the facility typically remains in operation.
For instance, polycarbonate panels are light enough to lift without a crane in most retrofit conditions. Furthermore, they arrive factory-built and pre-cut to the opening dimensions. That reduces field labor and limits the potential for measurement errors. The systems also attach to existing structures without major modifications to the supporting framing.
For architects specifying retrofit daylighting solutions, the SKYGARD 3700® is worth evaluating early in design. Its self-spanning capability removes the need for intermediate structural framing. As a result, this simplifies the structural analysis and reduces the number of trades involved. Similarly, knowing the full range of types of skylight early in design keeps specification options open. Also, early evaluation avoids value engineering compromises that affect long-term performance. Contact us today for a free consultation. We’ll help you get started with your next skylight project.
