Skylights can bring natural light, ventilation, and energy benefits to a commercial or residential building, but choosing the right type of skylight depends heavily on the roof system and installation requirements. Two of the most common options are curb-mounted skylights and deck-mounted skylights. While both provide overhead daylighting, they differ in how they attach to the roof, how they are installed, and where they are best suited.
Understanding the difference between curb-mounted and deck-mounted skylights can help property owners, facility managers, and contractors select an appropriate solution and avoid unnecessary roofing problems.
What Is a Curb-Mounted Skylight?
A curb-mounted skylight is installed on top of a raised structure called a skylight curb. The curb is typically a rectangular frame that extends above the roof surface, and the skylight unit is secured to this frame.
The curb may be constructed as part of the original roof installation or may already exist from a previous skylight. Because the skylight sits above the roof deck, curb-mounted systems can provide additional separation between the skylight and the roof surface.
One major advantage is replacement flexibility. If an existing curb is structurally sound and compatible with the new skylight, a replacement unit may be installed without completely rebuilding the curb. This can make curb-mounted skylights particularly useful for roof renovation and replacement projects.
Curb-mounted skylights are also widely used on commercial buildings and low-slope roofs where existing curb structures are already present.
What Is a Deck-Mounted Skylight?
A deck-mounted skylight attaches directly to the roof deck rather than sitting on a separate raised curb. The skylight is installed closer to the roof surface, creating a lower-profile appearance.
Because there is no separate curb extending above the roof, deck-mounted skylights can provide a streamlined installation and may be preferred when aesthetics and a lower overall profile are important.
Deck-mounted skylights are commonly used in applications where the roof construction and skylight design are specifically compatible. However, the installation must be carefully integrated with the roofing materials and flashing system to prevent water intrusion.
Curb-Mounted vs. Deck-Mounted Skylights: Key Differences
The simplest way to understand the difference is where the skylight attaches.
A curb-mounted skylight sits on a raised curb, while a deck-mounted skylight attaches directly to the roof deck. This difference affects installation height, appearance, flashing, replacement options, and compatibility with the existing roof system.
| Feature | Curb-Mounted Skylight | Deck-Mounted Skylight |
|---|---|---|
| Installation | Mounted on a raised curb | Mounted directly to roof deck |
| Profile | Generally higher | Generally lower |
| Replacement | Can be convenient when an existing curb is usable | Often requires more direct roof-deck integration |
| Appearance | More pronounced above roof | More streamlined |
| Flashing | Integrated around the curb | Integrated directly with roof system |
| Best suited for | Existing curbs and many commercial applications | Compatible roof assemblies and low-profile installations |
Which Skylight Is Better?
There is no single answer because the best skylight depends on the roof type, existing construction, drainage, flashing requirements, skylight dimensions, manufacturer specifications, and project goals.
For a commercial building with existing skylight curbs, a curb-mounted replacement may be practical and cost-effective. A deck-mounted skylight may be preferable when a low-profile installation is desired and the roof assembly is designed to accommodate it.
Regardless of the style selected, proper flashing and waterproofing are critical. An improperly installed skylight can become a significant source of roof leaks, especially on low-slope commercial roofing systems.
Professional Skylight Installation Matters
Choosing between a curb-mounted and deck-mounted skylight is only the first step. The skylight must be properly sized, secured, flashed, and integrated with the surrounding roofing system. The condition of the roof should also be evaluated before installation or replacement.
Shieldline Roofing can help property owners and facility managers evaluate commercial skylights, roof conditions, flashing details, and installation requirements. Professional assessment can help ensure the skylight performs properly without compromising the roof’s weatherproofing.
In short: a curb-mounted skylight sits on a raised curb, while a deck-mounted skylight attaches directly to the roof deck. The right choice depends on the existing roof assembly, installation requirements, appearance, and long-term maintenance considerations.
Related Questions
- What is the difference between a unit skylight and a structural skylight?
- What causes skylight leaks and how are they diagnosed?
- What is a tubular daylighting device and how is it flashed?
- What is a curb adapter and when is one used?
- How do skylights affect overall roof energy performance in Florida?
- Do skylights increase cooling loads more than they reduce lighting costs?
- Can skylights be permanently removed and infilled during a reroof?
- How do you inspect a skylight without walking on or near it?
Commercial Roof Repair in Florida
