Why Does My Skylight Leak? Common Causes & Fixes Before Summer

A skylight should brighten your home, not cause stress. Yet many New Zealand homeowners discover leaks around their skylights, especially after heavy winter rain. Left untreated, even a small leak can damage ceilings, cause mould, and reduce property value. With summer on the horizon, spring is the best time to identify the cause and take action.

Common Causes of Skylight Leaks

1. Worn or Damaged Seals

Over time, skylight seals can deteriorate due to:

Constant UV exposure
Temperature fluctuations
General wear and tear

Result: Rainwater seeps through gaps, leaving damp patches around the skylight.

2. Poor Installation

Incorrect installation is one of the leading causes of leaks. This can include:

Misaligned flashing
Insufficient sealing
Incompatible skylight and roof profiles

Illustrative Example Only: A Hamilton homeowner noticed water dripping onto their kitchen bench during spring storms. The cause? Flashings had been poorly aligned at installation, leaving small but critical gaps.

3. Blocked Flashings and Roof Debris

Leaves, moss, and dirt can collect around skylight flashings, especially in areas with overhanging trees. Blockages:

Stop water from draining correctly
Lead to pooling around the skylight
Increase the risk of leaks during heavy rain

4. Cracked or Damaged Glazing/Dome

Physical impact or long-term weathering can cause:

Hairline cracks
Cloudiness or brittleness
Water seepage through weakened areas

5. Condensation Confusion

Sometimes what looks like a skylight “leak” is actually condensation forming on the inside surface. This is common in poorly ventilated spaces like bathrooms or kitchens.

Fixing Skylight Leaks: What Homeowners Can Do

Short-Term DIY Actions

Clear leaves, moss, or dirt from around the flashing.
Check interior surfaces for condensation, not leaks.
Re-seal small gaps with a temporary waterproof sealant (professional repair still recommended).

Professional Solutions

Seal Replacement: Installers can replace failing seals to restore watertight protection.
Flashing Repairs: Correct installation or replacement ensures proper drainage.
Glazing/Dome Replacement: Swap cracked or damaged parts to prevent worsening leaks.
Ventilation Upgrades: In bathrooms or kitchens, adding a vented skylight can eliminate persistent condensation issues.

Preventing Future Leaks

Schedule an annual skylight inspection in spring.
Keep roof and skylight surrounds clear of debris.
Choose professional installers familiar with NZ roof types.
Consider modern skylight upgrades with built-in venting and UV protection.

Checklist: Spotting & Solving Skylight Leaks

Inspect seals for cracks or deterioration
Clear debris from flashing surrounds
Check for cracks in domes or glazing
Distinguish leaks from condensation
Book a professional inspection if issues persist

Conclusion: Stay Ahead of Summer Damage

A leaking skylight is more than an inconvenience — it’s a risk to your home’s health and comfort. By spotting the warning signs now and fixing problems in spring, you can enjoy bright, leak-free natural light all summer long.

Concerned about skylight leaks? Request a professional inspection here.