Velux Skylight Leaking Around Glass: Causes, Fixes, and Maintenance

The Velux skylight is a popular choice for bringing natural light into homes, but leaks around the glass can cause water damage and drafty interiors. This article explores why Velux skylights may leak around the glass, how to diagnose the issue, practical DIY fixes, and when to call a professional. Understanding common causes and effective remedies helps homeowners protect interiors and preserve the skylight’s performance.

Common Causes Of Leaks Around Glass On Velux Skylights

Leaks around the glass on Velux skylights typically stem from defects or wear that compromise the assembly’s weather seal. Key causes include:

• Over time, the sealant around the glass can crack or shrink, allowing water to seep in between the glass pane and the frame.
• A failed gasket can create gaps where water infiltrates, especially during heavy rain or wind-driven spray.
• The flashing that directs water away from the roof around the skylight may lift, crack, or deteriorate, letting water reach the glass edges.
• Condensation on the inside of the glass can appear as leakage, but true leaks may occur when warm, moist air condenses and drips near the glass edge if the unit is poorly vented.
• If the skylight was not installed correctly or has settled, seals and flashings may not seat properly, creating leaks around the glass.
• Clogged drainage paths or intake vents can cause water to back up and seep around the frame and glass.

Diagnosing Leaks Around Glass On Velux Skylights

Accurate diagnosis saves time and avoids unnecessary repairs. Follow these steps:

• Look for lifted, cracked, or missing flashing around the skylight. Check for dark streaks or staining on roofing material, which indicates water intrusion pathways.
• Examine the perimeter sealant for cracks, gaps, or gaps in the line where glass meets the frame. Press gently to test for looseness.
• If the skylight uses a gasket, inspect for deformation, tears, or shrinkage that may compromise a tight seal.
• Look inside for water trails along the glazing bead, rust on metal components, or damp insulation, which signal ongoing leakage.
• Conduct a controlled test by spraying water on the glass and frame from different angles while inspecting the interior for leaks. Exercise caution to avoid damage.

If the leak is intermittent or difficult to locate, consider hiring a professional to perform a comprehensive inspection, including flashing assessment and sealant integrity.

Practical DIY Fixes For Leaks Around Glass

DIY fixes are often effective for minor sealant wear or gasket issues. Always prioritize safety when working on a roof or elevated skylight.

• Replace degraded sealant: Remove old sealant from the glass edge and frame, clean with an appropriate solvent, dry thoroughly, and apply a high-quality exterior silicone or polyurethane sealant recommended for skylights. Tool the seal to ensure a smooth, continuous bead.
• Replace worn gaskets: If your Velux model uses edge gaskets, purchase the correct gasket kit from Velux or a certified supplier. Remove the old gasket, clean the groove, and install the new gasket according to manufacturer instructions.
• Re-seat the skylight: If the unit shifted, gently reposition it to align the glass with the frame. Re-tighten or adjust mounting screws per the installation guide while ensuring flashings stay properly aligned.
• Clear drainage paths: Remove debris from roof flashing channels and around the skylight to prevent water backup. Ensure off-ridge slope is intact to promote drainage.
• Reflash with a compatible kit: For damaged flashings, use Velux flashing kits designed for retrofit repairs. Follow the kit instructions precisely to maintain roof integrity.

Note: Some repairs, especially those involving flashing replacement or reinstallation of the skylight, may require professional expertise to ensure a watertight seal and to maintain warranty validity.

Maintenance And Prevention To Reduce Future Leaks

Proactive maintenance helps extend skylight life and reduce leak incidents. Recommended practices include:

• Check seals, gaskets, and flashings at least twice a year, or after severe weather. Look for cracks, warping, or loose components.
• Keep the glass clean to spot moisture buildup. Wipe the frame and sealant beads with a mild cleaner and a soft cloth, avoiding harsh solvents that can degrade seals.
• Trim branches and remove debris around the skylight to minimize damage and water pooling near the flashing.
• Ensure proper interior ventilation to minimize condensation that can seep or drip along the glass perimeter.
• If the original sealant has aged, consider re-sealing the area with a UV-resistant, exterior-grade sealant recommended for Velux skylights.

When To Call A Pro And Warranty Considerations

Not all leaks are suitable for DIY fixes. Circumstances that warrant professional intervention include:

• If the skylight is loose, cracked, or has significant flashing damage, professional installation or flashing replacement is advised.
• If sealing and gasket replacement do not stop the intrusion, a pro can assess hidden causes such as roof pitch changes or substrate movement.
• Velux warranties vary by model and installation. Retain purchase receipts, installation records, and photos of the issue to determine coverage. Many seals and flashing components are warranty-covered when installed correctly.

For a professional assessment, contact a Velux-certified installer or a licensed roofer with skylight experience. They can confirm the root cause, perform flashing work, reseal, or replace the skylight assembly if necessary.

Preventive Tips To Extend Velux Skylight Life

Prevention reduces future leaks and extends performance. Consider these strategies:

• Annual inspections by a Velux-certified technician can detect wear before leaks develop.
• Always use Velux-approved flashing kits, sealants, and gaskets designed for your model to maintain compatibility and warranty validity.
• If a skylight is newly installed or recently replaced, have the installation checked for proper alignment and flashing seal integrity.
• Different Velux models (venting, fixed, or autonomous systems) have unique sealing and flashing requirements. Consult the user manual for model-specific guidance.

By combining routine inspection, targeted repairs, and proper maintenance, homeowners can keep Velux skylights watertight and functional for years to come.