Not Every Metal Should Touch Every Other Metal

When certain different metals contact each other in the presence of moisture, an electrochemical reaction can accelerate corrosion.

This is known as:

Galvanic corrosion.

The Metal Construction Association specifically warns that incompatible dissimilar metals and certain fasteners can create corrosion problems in roofing systems.

Where Can This Happen?

Possible interactions include:

• Panels and fasteners
• Flashing metals
• Copper runoff onto aluminum
• Metal in contact with certain treated wood

Why Does Water Matter?

Moisture acts as the electrolyte that helps the reaction occur.

That means drainage paths also matter.

Why Fastener Choice Is Important

A roof panel may last decades.

Using an incompatible fastener can create a weakness around every attachment.

Can Corrosion Simply Be Painted Over?

Not without first understanding the cause.

If incompatible materials remain in contact, corrosion can continue.

Metal Roofing Is a System of Compatible Materials—not Just Panels.

Envirotech Exteriors considers fasteners, flashing, drainage, and adjacent metals when installing or repairing metal roofing.