See how wind creates competing pressures above and below your skylight glazing. The net uplift determines curb strength and anchor requirements for Miami-Dade HVHZ compliance.
Different curb types for different applications and load requirements.
Wood Frame Curb
Lumber frame with plywood sheathing. Cost-effective for residential and light commercial. Maximum 4'x4' opening typical.
Up to 80 psf uplift
Aluminum Curb
Extruded aluminum with thermal break. Integrated flashing and counter-flashing. Popular for commercial flat roofs.
Up to 120 psf uplift
Steel Frame Curb
Structural steel tube frame with heavy gauge metal cladding. For high wind zones and large openings. Welded connections.
Up to 180 psf uplift
Miami-Dade Zone Requirements
Uplift pressures vary dramatically based on location on the roof.
Roof Zone
Location
Net Uplift
Fastener Spacing
Min Curb Height
Zone 1 (Field)
Interior roof area
75 psf
12" o.c.
6"
Zone 2 (Edge)
Within 10% of dimension from edge
113 psf
8" o.c.
8"
Zone 3 (Corner)
Within 10% from corner both ways
140 psf
6" o.c.
8"
* Values for 180 mph, Exposure C, enclosed building. Actual loads depend on building geometry and enclosure classification.
Skylight Curb FAQs
Common questions about skylight wind loads in Miami-Dade.
What wind loads do skylight curbs experience in Miami-Dade?
Skylight curbs in Miami-Dade HVHZ experience severe uplift loads. The glazing sees positive pressure from below and negative pressure from above, creating a net uplift. At roof corners (Zone 3), a 4x4 foot skylight might see uplift pressures of 100-140 psf, requiring heavy-duty curb construction and anchoring.
Do skylights need Miami-Dade NOA approval?
Yes. All skylights and skylight curbs installed in Miami-Dade HVHZ must have a valid NOA (Notice of Acceptance). The NOA covers the complete assembly including the curb, glazing, frame, and fasteners. It specifies the maximum wind speed rating and installation requirements for each roof zone.
How do you anchor a skylight curb to the roof structure?
Skylight curbs are anchored through the roof deck into the structure below. For wood framing, lag screws into blocking or framing at maximum 12 inch spacing. For steel decks, self-drilling screws or welded clips. For concrete, expansion or adhesive anchors. The curb must have continuous support around its perimeter.
What is the difference between curb-mounted and deck-mounted skylights?
Curb-mounted skylights sit on a raised curb that projects above the roof surface, typically 4-12 inches high. Deck-mounted skylights sit directly on the roof deck with integral curbing. In hurricane zones, curb-mounted skylights are generally preferred because the curb provides better structural support and easier waterproofing.
Why do skylights fail during hurricanes?
Skylights fail during hurricanes from: glazing breakage from debris impact or excessive pressure, curb separation from inadequate anchoring, frame failure from wind pressure, and flashing failure leading to water intrusion. Impact-rated glazing and properly engineered curbs are essential in Miami-Dade.
Calculate Your Skylight Wind Loads
Get the exact uplift pressures and curb requirements for your Miami-Dade skylight installation.
WindLoad.co