This largely depends on the presence or absence of mineral granules.
Problem:
When non-mineralized bitumen membranes are exposed to sunlight (UV radiation), this radiation breaks down a few microns of the upper layer of the roofing membrane. The breakdown products react with oxygen and water to form a water-soluble carbonic acid or “resin water” (pH 3 to 4), which is washed away by rainwater. These acidic breakdown products can, over time, corrode zinc and lead.
These acids are also formed in the atmosphere due to exhaust gases from airplanes and cars. This phenomenon is known as “acid rain” and is responsible for about 20% of the corrosion of zinc and lead.
Solution:
If the bituminous membrane has a factory-applied mineral coating (mineral granules or slate granules), the above problem is significantly reduced.
If zinc gutters are treated with a specific liquid product (Zinc renovation from our IKOpro liquid range), they will no longer be corroded by acid rain. This means 100% long-lasting protection of the zinc.
Preferably use mineralized membranes.