Materials guide · Guide 61 of 101

Metal compatibility in slate roof flashings

Slate can remain serviceable longer than many sheet metals. Flashing selections should combine durability, workability and compatibility with adjacent metals and runoff.

01

Map every metal in the drainage path

Gutters, valleys, step flashings, fasteners, snow guards, HVAC components and masonry accessories may interact directly or through runoff. A compatible detail considers the whole roof, not one flashing in isolation.

02

Separate unlike materials where required

Dissimilar metals can create galvanic action in the presence of moisture. Suitable separation layers, compatible fasteners and drainage direction reduce risk, but the best solution is often a coordinated metal palette.

03

Account for movement

Long metal runs expand and contract. Seams, cleats and attachments should allow movement without tearing corners or stressing slate edges.

Further technical reading

Recognized sources behind this guide

Slate Boss writing is original. These links provide additional standards, preservation guidance and industry reference material.

View all slate roofing guides