Flashing Done Right: How Flashing Protects Skylights From Water Damage

A skylight adds light, character, and energy to any room. But without proper flashing, it’s essentially an invitation for water damage. Flashing is the unsung hero of skylight installation, and understanding what it does and what happens when it fails helps homeowners make smarter maintenance and repair decisions.

What is Flashing?

Flashing is the metal barrier installed where your skylight meets the roof. It bridges the gap between two different surfaces and creates a watertight seal that sheds water away from the opening. Most flashing is made from aluminum, copper, or galvanized steel, and when it’s installed correctly, it handles everything the Chicagoland climate throws at it.

A skylight system typically includes step flashing along the sides, saddle flashing at the top, and counter flashing to lock everything in place. Each piece has a job, and when one fails, the whole system is compromised.

Why Flashing Fails

Flashing doesn’t last forever. Several things can cause it to break down over time:

• Thermal expansion and contraction
• Improper installation at the seams
• Corrosion from moisture exposure
• Ice dam pressure in winter
• Worn or missing sealant
• Storm damage or impact

In the Chicago area’s climate, freeze-thaw cycles take a heavy toll on flashing. Water gets into a small gap, freezes, expands, and forces it wider. Over several seasons, what started as a minor imperfection becomes a real problem.

How to Know If Your Flashing Is Failing

Flashing problems don’t always announce themselves with an obvious drip. A water stain on the ceiling near the skylight frame is the most common indicator. You might also notice peeling paint or warped drywall nearby. In the attic, look for moisture staining on framing or insulation directly beneath the skylight.

After any significant storm, check both the interior and exterior. Damaged or lifted flashing is one of the most common results of high winds, even when the rest of the roof looks fine.

What Professional Installation Looks Like

When flashing is done right, it’s almost invisible. Here’s what the process involves:

1. Clean, dry roof surface before any flashing goes down
2. Step flashing woven with shingles on each side
3. Watertight saddle flashing across the high side
4. Counter flashing sealed to the skylight frame
5. Quality sealant applied at every seam and joint

Each step builds on the last. Skipping or rushing any one of them is where leaks are born, sometimes immediately and sometimes years later when the first real test arrives.

Staying Ahead of the Problem 

Preventing skylight leaks starts with regular attention to the flashing. A visual inspection every spring and fall takes just a few minutes and can catch early signs of deterioration before they become water damage. If the sealant looks cracked, the metal looks corroded, or anything appears shifted or lifted, don’t wait.

Professional inspections matter too. Flashing failures aren’t always visible from the ground or even from the attic. An experienced roofer can spot easy-to-miss problems and repair them before the damage compounds.

Preventing skylight leaks really comes down to understanding flashing. Keep it in good shape and your skylight stays an asset. Ignore it and it becomes a problem. If you’re unsure about your flashing’s condition or considering a new installation, the team at Lindholm Roofing’s skylight services can help you get it right from the start.

Whether you need roofing services in Wilmette, Norridge, Park Ridge, or the surrounding Chicago areas, Lindholm Roofing has the experience to protect your home from the top down.