Skylight Leaking but Only Sometimes: Intermittent Leak Troubleshooting

A skylight that leaks only sometimes can be one of the most frustrating roof problems to deal with. You might see water during certain storms, after snow melts, or only when rain comes from a specific direction. Intermittent skylight leaks are common—and they usually point to a flashing, drainage, or installation issue rather than a cracked skylight.

If you’re dealing with an on-and-off leak, you’re in the right place. Below is how to identify what’s causing it, what conditions trigger intermittent leaks, and how they’re properly fixed.

Why Skylight Leaks Can Be Intermittent

Unlike steady leaks, intermittent skylight leaks depend on weather conditions. Wind direction, ice buildup, and heavy rainfall can push water into weak points that stay dry most of the time.

That’s why leaks may appear:

• Only during heavy rain
• Only with wind-driven storms
• After snow or ice melts
• During freeze-thaw cycles
• When debris blocks drainage channels

Understanding when the leak happens is key to diagnosing it correctly.

Common Signs of an Intermittent Skylight Leak

• Water stains that appear and disappear
• Bubbling or peeling paint near the skylight
• Damp drywall after storms but dry in fair weather
• Drips that stop on their own
• Wet insulation around the skylight shaft

If you’re unsure whether the moisture is coming from the roof or another source, the diagnostic articles in the blog (https://leakyroof.us/blog/) can help rule out condensation or plumbing issues.

Most Common Causes of On-and-Off Skylight Leaks

Flashing Problems

Improper or deteriorated flashing is the top cause of intermittent skylight leaks. Water may only enter when rain is heavy or blowing in a certain direction.

Blocked Drainage Channels

Many skylights are designed with small drainage paths. Dirt, leaves, or debris can block these channels, causing water to back up and leak inside during heavy rain.

Failed Sealant or Gaskets

Sealants and gaskets around skylights can dry out or crack over time. These failures often leak only under specific weather conditions.

Ice Dams and Snow Melt

In colder climates, ice can trap water around skylights. When temperatures rise, melting snow forces water under flashing and into the home.

Roof Material Issues Around the Skylight

Worn shingles or roofing materials near the skylight can allow water to enter even if the skylight itself is intact.

How Professionals Troubleshoot Intermittent Skylight Leaks

Because these leaks aren’t always active during inspections, professionals focus on patterns rather than just visible water.

Leak troubleshooting may include:

• Inspecting skylight flashing and seals
• Checking for proper drainage and slope
• Examining roof materials around the skylight
• Looking for signs of past moisture in the attic
• Testing with controlled water flow

You can schedule a leak-focused skylight inspection through the services page (https://leakyroof.us/services/) to pinpoint the cause before it turns into a constant leak.

Repair Options for Intermittent Skylight Leaks

Flashing Repair or Replacement

This involves removing surrounding roofing materials and installing proper skylight-specific flashing kits to create a watertight seal.

Clearing or Improving Drainage

Blocked drainage channels are cleared, and water flow is corrected to prevent backup during storms.

Seal and Gasket Replacement

Replacing failed seals and gaskets can stop leaks caused by aging materials.

Roof Repairs Around the Skylight

If the surrounding roof is deteriorated, targeted repairs help prevent water from reaching the skylight opening.

Skylight Replacement

If the skylight itself is old or poorly installed, replacement may be the most reliable long-term solution.

What Not to Do When a Skylight Leaks Occasionally

• Don’t assume the leak is “random”
• Don’t repeatedly apply caulk without diagnosis
• Don’t ignore attic moisture or ceiling stains
• Don’t wait for the leak to become constant

Intermittent leaks almost always worsen over time.

When to Get Help

If your skylight leaks only under certain conditions, early troubleshooting can prevent mold, insulation damage, and costly interior repairs.

Reach out through the contact page if you need emergency help or want to schedule an inspection (https://leakyroof.us/contact-2/). You can also use the locations page to see if your area is covered (https://leakyroof.us/locations/).

For more step-by-step leak diagnosis guides and prevention tips, visit the blog (https://leakyroof.us/blog/).