Fix Leaking Skylight on a Metal Roof

The combination of a skylight and a metal roof can create a reliable, bright space, but leaks are a common problem. Leaks often stem from improper flashing, sealant failure, or condensation issues that allow water to travel along roof planes and into the interior. This guide provides a practical, step-by-step approach to diagnosing and repairing a leaking skylight on a metal roof, along with preventative maintenance to extend the life of the roof assembly.

Common Causes Of Leaks Around Skylights On Metal Roofs

Identifying the root cause is essential for a lasting fix. Common issues include damaged or degraded flashing, , poor installation or spacing, and condensation buildup in humid climates. Metal roofs expand and contract with temperature changes, which can stress sealants and flashing. Defective skylight units or improper flashing integration with the metal roof decking can also permit water intrusion. Inspect for visible gaps, rust around flashing beads, and cracked or missing shingles or panels near the skylight.

Tools And Safety Precautions

Before any repair, ensure safety and have the right tools. Gather ladder stabilizer, utility knife, caulking gun, butyl tape or high-quality roofing sealant, silicone sealant compatible with metal, roofing cement, stainless steel screws, snap-lock metal panels, patching material for metal, caulk removal tools, and protective gloves. Use fall protection, work with a partner, and avoid performing repairs in wet or windy conditions. Properly ventilate the attic space when inspecting interior signs of moisture to identify hidden leaks.

Step-By-Step Diagnostic Process

Start by locating the source of the leak from the interior: look for staining, damp insulation, or mold around the skylight. Then inspect the exterior in this sequence:

• Check the skylight curb flashing and sealant bead for cracks, gaps, or peeling edges.
• Inspect metal roof flashing around the skylight for corrosion or lifted edges.
• Examine the edges where the skylight meets roof panels for compression damage or improper seating.
• Look for condensation inside the skylight frame that could indicate airflow or insulation issues rather than a water entry point.
• Confirm the path of water intrusion during a rain test by having a helper gently spray water near the skylight perimeter while monitoring interior signs.

Repair Approach: Flashed Skylight On A Metal Roof

A proper repair focuses on flashing integrity, sealant performance, and ensuring a watertight seam. The following methods cover common scenarios:

• Reinforce or replace curb flashing: If flashing is cracked, corroded, or loose, remove the affected section and install new curb flashing. Clean surfaces, apply a continuous bead of roofing sealant, and secure with corrosion-resistant screws. Use butyl tape beneath flashing to improve seal integrity.
• Sealant replacement: Remove old sealant along the skylight perimeter using a plastic scraper. Clean with mineral spirits or a compatible cleaner, dry thoroughly, then apply a continuous, ¼-inch bead of high-temp, weatherproof silicone or urethane sealant designed for metal roofs. Tool the sealant for a smooth, even finish.
• Repair or replace gaps at the skylight interface: If gaps exist where the skylight meets the curb or panels, install new backer rods where applicable and re-seal. For larger openings, consider a stainless-steel or aluminum trim cap to cover the seam and provide an additional barrier against water intrusion.
• Install or replace flashing membranes: Use a self-adhesive flashing membrane rated for metal roofs over the curb and along the skylight perimeter. Ensure seams are overlapped and pressed firmly to eliminate bubbles and gaps.
• Address panel-to-skylight integration: If roof panels overlap the skylight, ensure proper side flashing and end dams to prevent water from traveling under panels toward the skylight.

Concrete Steps For A DIY Repair (Summary)

• Shut off moisture sources and set up safety gear.
• Remove failed sealant and clean the area around the skylight.
• Inspect curb flashing and metal roof seams; replace or reinforce as needed.
• Apply new sealant or flashing membranes, ensuring full coverage of all potential water entry points.
• Test with a controlled water spray and observe interior indicators for any remaining leaks.

When To Replace The Skylight Or Entire Skylight System

Repair is often effective, but certain conditions warrant replacement. Consider replacement if: the skylight unit shows significant warping or cracks, curb flashing is severely corroded or damaged beyond patching, or multiple leaks recur after multiple repair efforts. If the skylight is older than 15–20 years or uses outdated weatherproofing materials, replacement with a modern, energy-efficient unit may provide long-term savings and better performance on a metal roof.

Maintenance Tips To Prevent Future Leaks

Maintenance is key to extending the life of a skylight on a metal roof. Implement these practices:

• Regular inspections after major weather events to catch early signs of wear on flashing and sealants.
• Clean gutters and debris around the skylight area to prevent standing water and ice dam formation on metal surfaces.
• Use thermal breaks and ventilation to minimize condensation within the skylight and attic space.
• Apply protective coatings or repaint metal surfaces to reduce corrosion risk around flashing and curb areas.
• Schedule professional inspections every few years to assess flashing, curb integrity, and sealant performance beyond DIY fixes.

Choosing A Professional For A Metal Roof Skylight Repair

When professional help is needed, select contractors with proven experience in metal roof systems and skylight installations. Request references, verify licensing and insurance, and ask about warranty coverage on both materials and workmanship. A qualified contractor should provide a written assessment detailing the leak’s source, a recommended repair plan, and a transparent cost estimate. For insurance considerations, document interior damage and keep records of repair work and materials used.