A roofing system can be confusing to some as there are a list of materials that complete a whole roofing bundle, and many potential homeowners may feel that anything other than a basic shingle package is unnecessary, but repairing and/or replacing a roof goes beyond just shingles. There is more to add to the package with other materials that complete the system, and flashing is part of that system. So, exactly what is flashing and its purpose?
Flashing is a weatherproof material. It is thin and flat and supplements the underlayment of a roof. It aids in keeping the underside of shingles from getting wet. Flashing is composed of different metals such as stainless steel, galvanized steel, aluminum or copper.
Where Flashing is Used
Flashing is used in various sections of a roof. It is usually found where the surface of the roof has contact with a wall, such as the sidewall and front walls of a home. Flashing is also utilized where the slopes or valleys of a roof meet as well as with protrusions such as venting and skylights. Most homeowners think of flashing as a placement on the edges of a roof, which are identified as the rakes and eaves.
Types of Walls
Since flashing is used at various junctures of a roof and the walls it contacts, the types of walls most affected include:
Sidewalls – which are vertical walls that fall along the edge of a roof deck where a slope is present.
Front Walls/Headwalls – which are vertical walls that are behind a roof deck that has a slope to it.
Weather and Flashing
Weather is going to affect the walls of a home. Wind-driven rain is traveling in a rushing manner and will batter against the walls of a home, and the water will take a path down the wall and into the joint where the roof deck and wall meet. Flashing will stop this water stream so the water is unable to penetrate the area between the wall and the shingles. Any excess water will be transported to the gutters. So flashing actually helps to channel the moisture away from the wall and shingles and into the gutters.
Types of Flashing – Uses
Step flashing – is used when a roof deck makes contact with a sidewall. It is used in pieces that are bent in an angle formation that is in line with a roof’s pitch. They are installed along the sidewall where the roof deck and the sidewall join. The step flashing will be somewhat revealed along the wall and in order to create a more aesthetically pleasing look, a decorative type of flashing, such as copper or other ornate material can be used.
Base flashing – is used for front walls. It is presented in a length that is bent along the entire length in order to correlate with the roof’s pitch. It is installed over the underlayment on a roof and under the shingles and siding, so it may not be visible looking up towards it from the ground.
Valley flashing – is used where two roof decks slant toward each other. A low line is created that is similar to a valley that appears between mountain ranges. Rainwater can work its way into the valleys of a roof and can penetrate and saturate the area. Metal valley flashing is placed over underlayment but is put under shingle edges. The shingles are installed so they do not touch yet overlap and create a gap where the flashing is exposed. This formation enables water to flow over the roof’s edges into the flashing and on down into the gutters. The flashing can be seen from the ground, so oftentimes homeowners will use a contrasting color or similar color as the shingles themselves to create a unique and finished look.
Flashing for Penetrations
More complex roof features such as vents, chimneys, skylights, dormers, and any other penetrations require varying materials, flashing components and installation techniques that protect these different penetrations and make them watertight. Maintaining these features is important to the overall stability and performance of a roof and that means dealing with extremes in weather and how they can affect a roofing system. Proper flashing components are a definite must for penetrations and with new and various technologies, flashing materials continue to be updated and made compatible with roofing systems used today.
Flashing at the Rake Edge and Drip Edges
With wind being one of the main causes of roof damage, flashing that is wrapped and secured at the rake edge serves as protection during severe winds where shingles can be ripped away along the rake edges. When shingles are not secured with a shingle overhang at the edges of a roof, flashing provides an added layer of protection.
In addition to flashing, the drip edge is another layer of protection at the eaves of a roof. The drip edge also protects the fascia board of a roof so water is unable to cause damage because of blocked gutters, ice buildup or other issues. Though some roofs may not need flashing, most any roof can use the protection from drip edge applied at the eaves level.
Roof flashing will vary with the distinctive features of a roof as well as the type of shingles used, along with the specific design and style of a home. If you are unsure of exactly what type of flashing your home may require, complete the online contact form and a roofing expert will get back to you with information that can better help you make an informed decision.