Installing a curb mount skylight can brighten a space with natural light while maintaining weather tightness. This guide explains a practical, step-by-step approach for homeowners and contractors in the United States, covering planning, materials, and installation practices that optimize performance and durability. Proper execution reduces potential leaks and improves energy efficiency, making curb mount skylights a reliable choice for suitable roof configurations.
Planning And Preparation
Before any cutting begins, confirm that the roof structure, framing, and existing shingles or tiles can accommodate a curb mounted skylight. Verify building codes, local requirements, and any permits needed for roof penetration. Assess daylight goals, skylight size, and placement to maximize daylight distribution and minimize glare. Review warranty stipulations from the skylight manufacturer, especially regarding curb height, flashing kits, and non-penetrating alternatives.
Tools And Materials
- Measuring tape, square, and chalk line
- Reciprocating saw or metal snips for frame work
- Hammer, nails, or galvanized screws
- Roofing nails or screws compatible with shingles or tiles
- Roof flashing kit designed for curb mount skylights
- Sealant or adhesive compatible with roofing materials
- Insulation materials such as spray foam or rigid foam boards
- Caulk gun and exterior-grade sealant
- Roofing underlayment or house wrap (if adding a new layer)
- Skylight curb, flashing, and glazing unit per manufacturer specs
- Safety gear: harness, gloves, eye protection, and stable ladder
Safety Considerations
Roof work carries fall risk. Use a sturdy ladder, stabilizers, and a fall arrest system when required. Work with a partner to pass tools and monitor footing on slopes. Ensure the roof is dry and free of ice, and avoid work during high wind conditions. Follow manufacturer installation instructions precisely to preserve warranty eligibility and ensure proper drainage around the curb.
Measuring And Fitting The Curb
Accurate measurement is critical for a tight fit. Measure the rough opening in the roof deck to align with the curb’s outer dimensions. The curb should extend just beyond the roof plane to ensure proper flashing integration. Mark the centerline of the opening and verify square with a framing square. If the existing roof has different substrates, plan for compatibility with the curb height and the chosen flashing kit. Dry-fit the curb to confirm fit before permanent installation.
Installing The Curb And Flashing
Begin by building or securing the curb frame to the roof deck, ensuring it is level and plumb. Fasten through the deck into underlying framing, using corrosion-resistant fasteners. Install the exterior flashing component according to the kit’s instructions. For curb mount skylights, the flashing often includes a base flange that sits over the curb, a vertical wall piece, and a top cap to direct water away from the skylight. Apply a continuous bead of sealant between the curb edge and the roof surface to create a watertight seal. Ensure proper overlap with the roofing material to prevent moisture intrusion.
Installing The Skylight Unit
With the curb and flashing secured, place the skylight unit onto the curb. Some models are fastened from inside the attic or ceiling, while others require exterior fasteners through predrilled holes in the curb. Align the skylight so the sash operates freely and opens fully if it is a venting model. Connect any electrical or motorized components per the manufacturer’s wiring diagram, and seal penetrations to prevent leaks. Recheck alignment and confirm there is no binding on the hinge or vent mechanism before finishing the interior trim.
Sealing, Insulation, And Finishing
Seal all gaps between the skylight curb, flashing, and roof deck with compatible sealant. Use spray foam or rigid insulation around the interior side of the curb to minimize thermal bridging and air leakage. Install interior trim or drywall around the skylight opening, leaving space for operation and condensation drainage. For energy efficiency, consider a low-emissivity (low-E) glazing option and ensure the skylight sealant remains compatible with your climate. If moisture appears in the attic around the curb, double-check flashing integrity and reapply sealant as needed.
Final Checks And Maintenance
Inspect the exterior after installation to confirm the flashing is continuous and free of gaps. Check the interior for any signs of condensation or draft around the skylight frame. Verify that the skylight operates smoothly and seals properly when closed. Schedule periodic maintenance, including cleaning the glass, inspecting flashing for damage after storms, and inspecting insulation for settling. Address any issues promptly to maintain weather resistance and energy performance.