Roof Leaking Around a Skylight: Causes, Inspection, and Fixes

The presence of a roof leaking around a skylight can cause interior damage, energy loss, and mold growth if not addressed quickly. This guide explains the most common causes, step-by-step inspection techniques, temporary and permanent repair options, cost expectations, and preventive maintenance to protect the home.

Topic	Quick Take
Common Causes	Flashing failures, sealant degradation, and roof material issues
Immediate Actions	Interior containment and temporary exterior patching
Permanent Repairs	Replace flashing, reseal skylight, or replace skylight unit
When To Call A Pro	Complex flashing, roof penetration complications, or large leaks

Why Skylights Leak: Common Causes

Skylights are attractive but create a roof penetration that requires careful detailing. The most frequent reasons for a roof leaking around a skylight include failed flashing, deteriorated sealant, roof deck movement, and improper installation.

Flashing, the metal or membrane that directs water around the skylight, can corrode, separate, or be improperly lapped, creating entry points for water. Sealant and gasket failure around the skylight perimeter is common over time due to UV exposure and thermal cycling.

Roofing material issues such as curled shingles, missing underlayment, or improper shingle integration with the skylight can also allow water to bypass the flashing. Additionally, poor installation angles or skylights placed under overhanging trees can increase leak risk.

How To Inspect A Skylight Leak Safely

Inspection should start indoors and progress to an exterior check if safe. Begin by locating wet spots, staining, peeling paint, or mold near the skylight to identify the leak path. Map stains from the interior upward to find the likely exterior source.

On the roof, only proceed if the roof is safe and dry. Look for cracked or missing sealant, gaps in flashing, loose or bent counterflashing, or shingles that do not overlap the skylight properly. Photograph all findings to document damage and assist a contractor if needed.

Check the skylight frame for condensation between panes, cracked glazing, or warping of the curb (the raised frame the skylight sits on). Water between glass panes indicates seal failure and often requires skylight replacement.

Temporary Fixes To Stop Further Damage

Temporary measures can limit interior damage until a permanent repair is scheduled. For interior protection, place buckets or tarps under the leak and move valuables away. Dry and remove wet insulation and ceiling material to prevent mold growth.

Exterior temporary fixes might include applying roofing tar or a waterproof sealant around obvious gaps and loose flashing. Use a UV-resistant roof sealant formulated for skylights. Cover the skylight with a heavy-duty tarp secured with roofing nails and boards if leakage is heavy and emergency protection is required.

Temporary fixes are not long-term solutions and should be followed by proper diagnostic work and repair. Avoid walking on wet roofs or applying heavy loads on skylights during temporary repairs.

Permanent Repair Options Explained

Permanent repairs depend on the cause and the skylight type. For flashing issues, the most reliable fix is to replace or re-flash with properly lapped metal or membrane flashing integrated with the roofing underlayment.

If the skylight curb is rotted or improperly installed, repair may require removing the skylight, replacing the curb, and reinstalling the unit with proper flashing and underlayment integration. When glazing seals fail, replace the entire skylight unit rather than attempting air sealing between panes.

For smaller leaks due to sealant failure, a thorough cleaning followed by application of a compatible roofing adhesive or urethane sealant can provide a durable repair. Ensure compatibility with the skylight frame material to avoid chemical damage.

DIY Repair Steps For Homeowners

Homeowners can handle minor repairs if comfortable working on roofs and have necessary tools. Start by cleaning the area and removing loose materials. Apply a compatible sealant to gaps between the skylight frame and roofing material and to seams in the flashing.

To re-flash, install step or counterflashing pieces under the existing shingles and over the skylight flange, ensuring a minimum of a 4-inch overlap for proper water shedding. Use roof cement sparingly for temporary holding only. Follow manufacturer instructions for skylight-specific parts and sealants.

If the job requires dismantling the skylight or rebuilding the curb, consider hiring a professional due to structural and waterproofing complexities.

When To Call A Professional Roofer Or Skylight Specialist

Call a pro if the leak source is unclear, if flashing needs full replacement, or if the skylight must be removed. Experienced contractors can perform a water test to pinpoint leak pathways and recommend the correct repair strategy.

Complex roofing systems—such as low-slope roofs, metal roofs, or roofs with multiple penetrations—require specialized flashing techniques. Professionals also ensure proper integration of ice and water shield membranes, underlayment, and shingle courses to prevent future leaks.

Choose a contractor experienced with skylights, ask for references, and verify insurance and licensing. Request an itemized estimate that differentiates labor, materials, and warranty terms.

Cost Expectations For Skylight Leak Repairs

Repair costs vary widely by cause and access difficulty. Simple resealing or minor flashing repairs typically range from $150 to $600, depending on materials and labor rates. More extensive flashing replacement or curb repairs usually cost between $600 and $1,500.

Full skylight replacement, especially for higher-end units or custom flashing, can range from $800 to $2,500 or more for labor and materials. Costs increase for roof tear-offs, structural repairs, or interior ceiling replacement caused by prolonged leaks.

Request multiple quotes and warranties. A warranty on labor and materials for at least one year is common; longer-term warranties provide additional protection.

Preventive Maintenance To Avoid Future Leaks

Regular inspection and maintenance extend skylight life and reduce leak risk. Inspect skylights twice a year and after major storms. Clear debris, trim overhanging branches, and check sealant and flashing condition.

Maintain roofing shingles and underlayment around skylights and ensure proper attic ventilation to minimize thermal stress. Replace sealant at regular intervals based on manufacturer recommendations—typically every 5–10 years.

Consider installing a curb-mounted or self-flashing skylight designed for the roof type during replacement to reduce complexity and long-term leak potential.

Comparing Skylight Types And Leak Risk

Different skylight types carry different leak risks. Fixed glazed skylights typically have fewer leak points than venting models, which have moving parts and seals. Tubular skylights have fewer roof penetrations but can leak at the flashing or joints. Choose a skylight type that fits the roof pitch and exposure to minimize future problems.

Energy-efficient models with insulated glazing and thermally broken frames reduce condensation-related issues, which can mimic leaks but are caused by humidity and temperature differences instead of water intrusion.

Practical Checklist For Addressing A Roof Leak Around A Skylight

• Locate Interior Stain: Trace staining upward to find leak path.
• Document Damage: Photograph interior and exterior conditions.
• Contain Interior Water: Use buckets and remove wet insulation.
• Temporary Exterior Patch: Apply tarp or roof sealant if safe.
• Inspect Flashing And Sealants: Look for gaps, corrosion, or missing pieces.
• Decide Repair Scope: Reseal, re-flash, rebuild curb, or replace skylight.
• Get Professional Quotes: Obtain at least two estimates with warranties.
• Schedule Permanent Repair: Follow with interior repairs and mold remediation if needed.

Additional Resources And Warranty Tips

When purchasing replacement components, ask for manufacturer warranty details on the skylight and flashing. Retain documentation of repairs and warranties for future resale or insurance claims.

Research manufacturer installation guides and local building codes for roof penetrations. Many manufacturers provide step-by-step flashing kits designed for compatibility with specific skylight models, which reduce installation errors and long-term leak risks.

For insurance claims due to sudden leaks, document damage promptly and contact the insurer before performing non-emergency permanent repairs. Emergency temporary measures are usually allowable to prevent further damage.