roof flashing

Is Your Roof Leak-Proof? Understanding How Roof Flashing Works

A leaky roof is a major safety hazard for both your house and your family.

When it comes to your roof, you probably think the shingles, metal sheeting, tiles are what keep your home safe from water damage. While this is true, your roofing materials are not the only things that stand between your house and the elements.

Roof flashing is one of the most important components of a fully functioning roof. But if you’re like most homeowners, you don’t know much about it.

But the more you know, the better you’ll be able to keep your roof leak-free.

In this guide, we’ll go over everything you need to know about roof flashing and how to tell it’s time for repairs.

What Is Roof Flashing?

If you’ve ever studied your roof, you’ve probably seen thin metal strips around the chimney and along the roofline. These strips of metal are your roof’s flashing.

The flashing itself works with your roofing materials to create a more weather-proof and waterproof layer of protection for your house.

Most often, roof flashing is made from aluminum and steel. It’s lightweight, durable, and can stand up to most storms with ease.

But for homeowners on a tight budget, plastic and PVC flashing can be an option. These types are less durable and tend to break down in a few years.

How Does It Protect Your Roof?

Every roof, no matter what type, has seams where materials join together. These seams are a weak point for the roof itself.

Unless they’re covered, water, moisture, and even insects can get inside the roofing materials. Over time, this increases your risk of water damage, mold growth, and even puts your house at risk for insect infestations.

Flashing covers those seams and protects the interior structure of the roof from the elements.

Where Do Roofers Install It?

Roofers commonly install flashing where different slopes of the roof meet. These are known as valleys. The valleys can trap and collect water, snow, and moisture easily.

With flashing in place, the water won’t seep into the roof and can instead flow straight to the gutters.

But flashing is also ideal for protecting other parts of your roof.


Chimneys are a major leak risk for your home. To build a chimney, contractors have to leave a hole in the roofing. Once built, the chimney won’t sit completely flush with the roofing materials.

This increases the risk of leaks and water damage both to the roof and the walls of your home. Flashing is installed around the base of the chimney to seal the gap between the chimney wall and your roof. This creates a weather-tight seal and keeps your home safe and dry.


Skylights add great natural light to any room. But when you think about it, you realize they’re just a hole in the roof. This means they’re a major source of water leaks even if your roof is in good condition.

Flashing covers the gaps between the frame of the skylight and the roof itself. Sealant alone is not enough to stand up to the elements and needs the protective barrier flashing provides to keep your home safe.


Ventilation is a key part in helping keep humidity and moisture levels within the normal range in your attic. To help your roof disperse heat and maintain fresh air circulation throughout the attic, roofers install vents along the roofline.

These vents are framed holes in the roofing materials themselves. After installing the vent, roofers place flashing along the base of the vent. This keeps moisture out while allowing your attic to breathe.

Common Issues with Flashing

Most flashing is incredibly durable and can withstand the elements for years at a time. But like all roofing materials, it will eventually need repairs or a full replacement. Here are some signs to watch for.

Corrosion of the Metal

Aluminum and steel flashing will eventually rust. Over time, the rust eats through the metal, leaving holes and gaps in the flashing itself.

Your roofer will be able to determine if the corrosion is on the surface or if its time to replace the flashing.

Bent or Lifting Pieces

Flashing doesn’t sit completely flat against the roof. This means high winds can slip between the flashing and the roofing materials. In some cases, the wind can lift the flashing off, bending it in place.

This creates a gap where water and moisture slip into your roofing materials. Every few months and after severe weather, inspect the roof from the ground. If you notice bent flashing, call your roofer immediately.

Active Leaks in the House

Active leaks inside your home are a sure sign of roof damage. For most homeowners, telling the difference between a leak caused by damaged flashing and one due to damaged roof shingles can be tough.

If you notice a leak, schedule a roof repair appointment immediately. Remember, the average roof only lasts about 20 to 25 years. It’s normal for the materials to need a full replacement and the sooner you take care of it, the better off your home will be.

What Happens if Flashing Is Not Replaced

If damaged flashing is not repaired or replaced, you risk further water damage and leaks in your home.

The best thing you can do is stay on top of roof maintenance. Schedule a roof inspection at least once a year. During the inspection, your roofer will look for signs of damage both to the materials and the flashing.

After a severe storm or anytime you notice damage, schedule repairs immediately. The sooner the damage is fixed, the safer your home will be.

Keep Your Roof Flashing in Good Condition

Your roof flashing is your roof’s first line of defense against water damage and leaks. And the longer damage sits, the worse your roof will get.

Don’t wait. Contact us today to schedule a free roof repair estimate and inspection.

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