Flashing for Roofs

Roof Flashing and The Well-protected Home

Flashing is an essential element of a functional roof that generally garners far less scrutiny than the shingles. Typically made from thin sheet metal such as copper, galvanized or stainless steel, lead or aluminum, flashing can be concealed beneath shingles or exposed along the pipes, chimneys, skylights and roof joints that are vulnerable to leakage. Concealed material can be metal or a waterproof membrane of plastic, rubber or treated fabric.

When looking over a roofing bid, homeowners should be aware of the type of flashing that the installer plans to use for the project. The flashing estimate affects the total cost of the roof, and the material that the roofer selects will help determine the appearance of the finished project. Marlton roofing consultants are happy to discuss flashing options with customers.

While even inexperienced roofers can install most shingles effectively, flashing a roof takes experience and skill. If the flashing is not placed and secured correctly, water will find a way into the structure, causing mold growth and moisture damage. Hiring skilled roofers is especially important for ensuring that roofs with many valleys, junctures and penetrating pipes are completely watertight.

In areas of the roof where the installer must stop shingling due to a directional change or an obstacle such as a vent, flashing helps to maintain the integrity of the overall watertight seal. On roofs with composition shingles, the roofer places the flashing and then overlaps it with shingles, leaving a few inches of the sheet metal exposed to direct water flow. Some flashing is crimped along its center line to better channel runoff.

Roofers often conceal the flashing beneath clay tile and slate roofing so that it does not detract from the traditional look of the materials. Sometimes, composition installers shingle over valleys to get a more integral appearance, but they must first apply additional underlayment material in the valley beneath that serves as a moisture barrier in place of metal flashing.

When flashing becomes damaged or dislodged during harsh weather, savvy homeowners don’t waste time trying to fix the problem themselves, primarily because they want to be certain that their roof flashing is properly fixed before further water damage can occur. If left unchecked, a flashing leak can cause infrastructure deterioration, mildewed insulation and damage to ceilings in the home.

Flashing around components that penetrate the roof itself can easily become a source of leakage if not properly installed. Flashing that has moved or become cupped may function just the opposite of its intended usage, and channel water beneath the shingles and into the house. Repairing the flashing around a chimney or pipe is a fairly straightforward process that a professional can take care of in an afternoon.

When roofing contractors replace existing roofs, installing new flashing is not always necessary. If the pieces are in good repair and functioning properly, homeowners can ask roofers to reuse them when laying the new roofing material. When doing a roofover, they typically leave the existing flashing in place and install new flashing over it as necessary.Have a question regarding roofing, gutters or roof leaks? Please ask Fortified Roofing of Marlton NJ today!

Term of the day, courtesy of Fortified Roofing, Marlton NJ:


A valley is the meeting point of two sloped roof surfaces where water runoff from both slopes washes into the rain gutters. At a valley, the roofer must interrupt the continuous application of shingles or rolled roofing materials to change directions, making the area vulnerable to leaks.

Question and answer courtesy of a Marlton roofing contractor:

What is the most durable flashing material?

Copper is the most durable metal flashing material. It is more expensive than other types of flashing but weathers well and is easy to work with. Stainless steel is also a fairly durable flashing metal, but manufacturers recommend that it be replaced each time the shingles are. Aluminum flashing is affordable and easy to find, but it should be replaced when the home is reroofed. Aluminum requires a coating that protects it from corrosion.

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