Everything You Need to Know About Chimney Flashing

As a licensed roofing contractor in Hanover, PA, we have completed hundreds of roof inspections in Southern Pennsylvania and Northern Maryland. Roof inspections can tell you a lot about your home, especially during the colder months like why your energy bills significantly increased or why it always feels drafty inside. One of the items we often find needs fixed is the chimney flashing. The most common cause of failed chimney flashing is improper installation.

bad chimney flashing
This chimney flashing is not installed correctly.

Chimney flashing seals the gap between your roof and chimney. It prevents moisture like rain and melting snow from leaking through this space into your home. If left go for too long the unwanted moisture can cause serious interior damage including damage to the structure or mold. This is especially a concern in winter and spring in the northeast when the amount of moisture from snow and rain is unpredictable.

There are three different types of chimney flashing. Choosing the right one depends on where you live, type of chimney, and your existing roofing material.

Aluminum Flashing

Aluminum flashing is the most common type because it is the least expensive and can be used on any type of roof. The downfall to aluminum flashing is its high risk of corrosion.

PVC Flashing

PVC or vinyl flashing is a lightweight option that is also inexpensive. This is not the best flashing option if you live in areas with extreme temperatures or are subject to harsh weather conditions. The vinyl flashing doesn’t hold up well, becomes brittle, and breaks easily in these conditions.

Copper Flashing

Copper flashing is another option for roofing systems and stands up against high temperatures and other extreme weather conditions like storms. Copper flashing should be installed by a professional roofer because it requires a special sealant. For many homeowners, copper flashing is too costly. Before you decide it’s not right for you, discuss your options with a trusted roofing company.

Some contractors advertise a lightweight copper flashing which is a tape and not nearly as durable. Copper flashing is the heaviest of the three types and should be comprised of 16 ounces or greater copper weight.

Signs Flashing Needs Replaced

It is not always easy to tell if your chimney flashing is leaking. A good rule of thumb is to have a roof inspection every six months to minimize the possibility. If you notice water spots on your ceiling, increased energy bills, or a constant chill inside your home, schedule a roof inspection to see if a faulty flashing or roofing system is the culprit.

What Should Step Flashing Look Like?

Step flashings is needed where two areas of the roof meet. For example where the roof ties into the wall is the first step and the second occurs along the wall or chimney. It is crucial that you grind out mortar joints in a stepping pattern, bend the cap flashing tuck it into it while following the roof line.

right flashing installation