What Can Be Done About Galvanic Corrosion in Leader Pipes & Aluminum Gutters?

Galvanic Corrosion

• Galvanic corrosion occurs when different types of metal contact each other in the presence of an electrolytic substance. The moisture in the air and rain water are both electrolytic substances that can trigger corrosion between different types of metals. In gutter systems made with aluminum, galvanic corrosion will damage the parts of your gutter made from aluminum that are in contact with other types of metal. Since exposing your gutters to salt increases the rate of corrosion, avoid using ice melt on roof during the winter if your gutters show rust around fasteners or connections.

Replacement

• The most effective way to avoid galvanic corrosion is to ensure that all of the materials used in your gutter system are made from the same type of metal. If the part of your aluminum gutters where the leader pipes are attached is rusting but the pipes are not, then you will need to install aluminum replacements. Using aluminum fasteners to attach your gutters and leader pipes will also prevent corrosion damage to your gutter system.

Contact

• If replacing the leader pipes in your gutter system is not an option, you can use a nonconductive barrier to separate your gutters and leader pipes. Applying a protective coating of paint will prevent corrosion so long as there is no electrical contact between the leader and the gutter pipe. You can also use a physical barrier such as plastic sheeting to create a barrier between the top of the leader pipe and the gutter. Wrap a section of sheeting around the section of the gutter's downspout that extends into the leader pipe and secure it with tightly using nylon twine.

Considerations

• Damaged protective coatings can concentrate the damage to your gutters. If a small area of the aluminum gutter comes in contact with a larger area of leader pipe, it will corrode more quickly. If you decide to use a protective coating, make sure that you fully cover the gutter and the leader pipe everywhere they might come into contact.