The area around a skylight is a common source of roof leaks, especially after heavy rain, thawing, or wind-driven moisture. Leaks can stem from worn flashing, improper installation, damaged seals, or clogged drainage. Understanding typical failure points and a systematic inspection can help homeowners prevent water intrusion, protect attic spaces, and extend the life of the roof. This guide covers causes, safe inspection practices, DIY repair options for small leaks, and practical steps for when to hire a professional.
What Causes Leaks Around Skylights
Leaks around skylights usually arise from failures in weatherproofing components. Common culprits include damaged or missing flashing where the skylight meets the roof deck, deteriorated sealant around the skylight frame, and cracks in the skylight dome or glass. Improper installation can create gaps that allow water to follow the frame into the roof structure. Clogged or improperly sloped drainage tracks can also cause water to back up and seep through edges. Additionally, poor roof slope, aging roofing material, and ice dams in winter can push moisture toward the skylight perimeter.
Key failure points to examine include the curb flashing, step flashing at the transition to the skylight, and the sealant on the skylight curb. Environmental factors like hail damage, heavy wind uplift, and thermal expansion can stress these components over time. A skylight with a loose or degraded gasket around the sash can permit moisture intrusion even when flashing is intact. Understanding these failure modes helps prioritize inspection and repair efforts.
How To Inspect Safely
Begin with a dry day or use rubber-soled footwear and a sturdy ladder. Exterior inspection focuses on visible flashing, roofing sealant, and the skylight curb. Look for lifted metal flashing, gaps between flashing and shingles, and any cracked or missing sealant. Inside the attic, check for water stains, damp insulation, mold, or dark spots around the skylight framing. Pay attention to damp plywood or ceiling joists, which indicate a leak path that may extend beyond the skylight itself.
Document findings with photos, noting the location and likely source of moisture. If attic access is limited, use a flashlight to inspect the underside of the skylight curb from the interior and compare to exterior flashing. Do not probe under damaged flashing or into compromised roofing material from the exterior without proper protective equipment. For persistent leaks, consider temporary measures such as tarping the area above the skylight to limit further water entry while arranging repairs.
DIY Repair Steps For Small Leaks
Small, non-structural leaks around skylights can sometimes be addressed with careful sealing and flashing adjustments. The following steps provide a basic approach for homeowners with intermediate skills and appropriate safety gear.
- Clear debris: Remove leaves, pine needles, and dirt from the skylight surroundings and drainage channels to ensure proper water flow.
- Clean surfaces: Use a mild detergent and water to remove dirt and old sealant from the curb, flashing, and gasket areas. Rinse and dry completely.
- Inspect flashing: Check for loose or lifted flashing. If flashing is damaged, replace it with matching metal flashing and reseal with roofing-grade sealant.
- Seal gaps: Apply a high-quality, exterior-grade sealant around the skylight base and along flashing seams. Use a sealant compatible with roofing materials and UV-stable.
- Check the gasket: Inspect the skylight sash gasket for wear. If the gasket is cracked or deformed, replace it to restore a watertight seal.
- Re-seal joints: Apply sealant along all joints where the skylight meets the roof, ensuring a continuous seal to prevent water intrusion.
- Test: After resealing, run a garden hose over the skylight edge to simulate rain and observe for leaks inside the attic. Do not climb onto wet surfaces or press too hard on the skylight glass.
Note: If the skylight or surrounding roof skin shows signs of structural damage, or if the leak persists after adjustments, professional intervention is advised to avoid further damage.
When To Call A Pro
Professional help is recommended in several scenarios. If there is significant water damage in the attic, mold growth, or visible structural compromise, a licensed roofer should evaluate the system. If the skylight installation appears misaligned, or if flashing is severely degraded or corroded, skilled repair or replacement is warranted. Complex leaks around skylights with multiple flashing transitions or in modern low-slope roofs often require specialized equipment and techniques beyond DIY capabilities.
Request a comprehensive assessment that includes a written inspection report, a cost estimate for materials and labor, and a warranty description. For rental properties or homes with ongoing moisture issues, consider routine maintenance contracts with a trusted contractor to monitor skylight seals and flashing over time.
Preventive Tips And Maintenance
Preventing leaks around skylights focuses on regular inspection, timely maintenance, and proper installation practices. The following practices reduce the likelihood of moisture intrusion over time.
- Annual inspection: Check flashing, seals, and the skylight seal gasket at least once a year and after severe weather.
- Clean drainage paths: Ensure skylight gutters and valleys are free of debris to prevent water pooling near the curb.
- Maintain roof surface: Replace damaged shingles or roofing material promptly to prevent water infiltration at the skylight edge.
- Address ice dams: In cold climates, improve attic insulation and ventilation to limit ice dam formation that can force water under the skylight flashing.
- Quality installation: When replacing a skylight, opt for a curb-mounted or curbless installation with high-quality flashing and silicone sealant rated for exterior use.
- Ventilation: Ensure attic ventilation supports moisture control, reducing condensation around skylight areas.
Materials And Tools You Might Need
Having the right materials on hand can speed up minor repairs. Typical needs include:
- Roofing sealant: Exterior-grade, UV-stable sealant compatible with metal and shingles
- Butyl tape or flashing tape: For waterproofing seams
- Replacement flashing: Step flashing and curb flashing suited to the skylight type
- Gasket replacement kit: For the skylight sash gasket
- Putty knife and caulk gun: For applying sealant and sealing seams
- Small pry bar and metal snips: For adjusting flashing and trimming
- Safety gear: Ladder stabilizers, fall protection, gloves, eye protection
Choosing the right skylight style—venting, fixed, or tubular—can influence maintenance needs and leak vulnerability. Skylights with curb-mounted installations typically have more robust flashing options and may be less prone to leaks than flat or low-profile designs, but all require periodic inspection.