Roof Parts: What Is Flashing and Why Should You Care

Simply, roof flashing is any piece of sheet metal that forms a joint between the roof and objects that protrude from the roof, such as dormers, chimneys, and pipes, in such a manner that they prevent water from leaking through the joint. Virtually every house in America has at least one vent pipe or other penetration on the roof. Most likely, your old house has a chimney, perhaps several.

Depending on the complexity of your roof, you may have valleys, dormers, and any number of features that require flashing to properly shed rainwater. Neglected or overlooked flashing components are often the most vulnerable and leak-prone areas on a roof. The good news is that most roofs can be taken apart in areas around metal flashings and the metalwork can be replaced or reworked to prevent these leaks.

Basic Types of Roof Flashing

• Vent Boot: Also a vent pipe cover, is traditionally a lead or metal sleeve that fits over the top of a vent pipe penetration on a roof to help seal the section of roof around the pipe from water penetration.
• Valley Flashing: Metal or sometimes peel-and-stick material that protects an important area on the roof where two slopes come together to form a valley. Properly sized and installed valley flashing is key to channeling water safely off the roof.
• Ridge Cap: The piece of roofing that covers the peak or ridge of a roof. These are often a type of specialized shingle, tile, or fabricated metal specifically designed to aid in shedding water and debris. Because this is located at the very peak of the roof, only a small amount of water will hit the ridge through rainfall, unlike areas lower on the roof which will carry much higher volumes of runoff.
• Step Flashing: Small metal rectangles that are installed shingle fashion at the intersection between a roof and wall to prevent water intrusion into both the roof and wall and channel water back out onto the roof and safely off the house.
• Cricket: A framed-out, triangular structure that is built on top of an existing flat or pitched roof. Its design directs water away from these trouble spots to avoid leaks. Because of their sharp change of angles areas like chimneys and dormers or other large penetrations into a roof work best with a cricket.

When to Repair a Roof Flashing Leak

You might wonder what damaged flashing looks like and when to replace it. Check over your flashing and look for:

• Damage, holes, or bending.
• Corrosion or rusting.
• Loose or missing nails.
• Dried out or missing sealant.
• Flashing that has come loose.

If you find any of these problems, you may need to replace the flashing. If the original flashing is in good condition and can be removed without damaging it, it is possible to reuse it. However, you’ll need to prioritize proper fit and seal over saving money if you want a watertight roof; so be prepared to purchase new flashing where needed.

How to Repair Roof Flashing

Fixing roof flashing, just like installing flashing, is best left to roofing professionals.

• Step One: Gently pry up the shingles surrounding or covering the damaged flashing. When working with step flashing, this may involve removing undamaged pieces of flashing as well.
• Step Two: Take your chisel and gently remove any asphalt cement you find.
• Step Three: If you caught the flashing problem before a leak began, there should be no damage to the underlying roof parts and structure. However, it’s important to check for damage anyway. If you find damage, then you will have to get it repaired before reinstalling the flashing.
• Step Four: Now, reinstall the new flashing and shingles. Be sure to follow the proper order, as described above, especially when installing step flashing, to ensure the flashing will stand up to water.

Though roof flashing isn’t the most dramatic element of a roof, it is one of the most important. If you find some flashing on your roof that you’re concerned about, we suggest you contact a professional residential roofer like Legacy Construction. A professional can help you solve all of your roof flashing problems or answer the questions you have about your specific roof.