How Often Should You Replace Roof Flashing?

Articles | Roofing
April 13, 2023

While it’s often invisible, flashing is a crucial element of roof construction since it is responsible for keeping water from seeping through seams and causing damage to the interior. Made from simple sheets of corrosion-resistant metal, flashing helps to prevent the need for costly repairs to the rafters, siding, and underlayment.

Over time, however, the constant flow of rainwater will eventually cause the flashing to deteriorate. An experienced roofer can replace roof flashing, but the very fact that it’s usually hidden away underneath the shingles and other more visible elements means that you’ll need to be aware of how often to have this type of maintenance performed.

In this article, we’ll help give you an idea of the factors to take into consideration when deciding if your roof needs new flashing. We’ll also offer some advice for ensuring that your roof flashing lasts for as long as possible, which can save you a great deal of money on repairs in the long run.

Your Roof: The Basics

Most roofs are constructed with wooden rafters serving as the “skeleton” or framework. On top of these rafters is decking, which is constructed from wooden boards, plywood, or OSB. On top of the decking, the underlayment is installed. The underlayment is a waterproof layer, usually constructed from synthetic material. It’s excellent at keeping moisture from getting into the rafters and decking, but the seams—where each separate piece of decking meets—serve as weak points.

Without a protective layer covering these seams, rain and melted snow can seep in between them. This, in turn, will cause the decking and rafters to swell, warping them and weakening their overall structural integrity. It could also encourage the growth of mold, which can damage the roof further, as well as pose a major health risk to the inhabitants of a home.

Moisture that leaks in may not stop at the roof either. It can often get further, creating unsightly water stains on ceilings, dripping down walls, or even damaging property that is inside the home.

Flashing: The Unsung Hero

All of the potential damage we’ve mentioned above can be prevented with the proper installation of good flashing material. Your roof is constructed at an angle, known as the pitch, which allows water to flow off it. The flashing serves as a method of redirecting water away from vulnerable areas so that it can harmlessly make its way to the rain gutter and away from the home.

Flashing should be constructed of sturdy, lightweight material. Usually, stainless or galvanized steel is best, although aluminum and other metals can work just as well. Regardless of what material is used, flashing should always be constructed from high-quality metal. Inferior materials tend to corrode very quickly, forcing you to shell out for expensive repairs far more often than would otherwise be necessary.

It is absolutely vital that the flashing is installed correctly. Water happens to be very good at finding ways to enter your home, and poorly installed flashing can leave gaps that give it just the opening it needs. It’s also not a good idea to leave the old flashing in place when you replace roof flashing. It should be removed entirely to make way for the new to minimize the chances of leaving unprotected weak points near the seams of your roof.

How To Tell When It’s Time for New Flashing

The flashing that is used on today’s rooftops is treated specifically to avoid corrosion, which means it can last for many years, or even decades. In most cases, the flashing can last just as long as every other element of the roof. In other words, you won’t need to replace roof flashing until you need to replace the entire roof (usually about once every 15 to 20 years or so).

Despite this, roof flashing is just as susceptible to damage and decay as every other part of the roof, and you should be diligent about making sure it is regularly maintained and kept in good condition.


Visible rust is one of the key indicators that your flashing has begun to deteriorate. If the flashing is mostly covered by the shingles of your roof, this rust may not reveal itself until after an inspection; in other cases, it may be obvious. Either way, corrosion can cause holes to form in the metal that makes up the flashing, ultimately leading to leaks.

Often, it is possible for your roofer to patch the flashing using a piece of the same material it’s made from and a small amount of roofing cement. If the rust has spread too extensively, however, your roofer may decide that it is necessary to replace the flashing.


Sometimes, gaps may develop underneath the flashing as a result of it loosening over time, often due to the constant barrage of heavy winds against the roof. Generally speaking, this is a relatively easy fix for a roofer. However, sometimes gaps underneath the flashing can allow moisture in, which can then encourage the growth of mold. Mold patches underneath the flashing can necessitate a more extensive roof repair job.


Occasionally, damage to the roof flashing can be fast and sudden, as opposed to gradual. This can occur as a result of a windstorm or due to tree branches falling onto the rooftop. Any of these situations can cause pieces of the flashing to break away, forcing you to call a roofer in to perform an emergency replacement.

Who to Call When You Need Replacement Roof Flashing

Replacing roof flashing is always a job that should be undertaken by a professional roofer. Partially due to the complexity of the tasks involved, and partially because climbing around on a rooftop involves a certain level of safety training, as well as specialized equipment, such as roofing ladders and harnesses.

If you need to replace roof flashing, or for that matter, repair or replace any part of your roof, contact the professionals at Interstate Roofing. With over 35 successful years in the industry, Interstate Roofing can assist you with all of your roof repair and replacement needs.