Home Inspection Flashcard #137

Roof, Asphalt Shingle

What's Your Call?

What is the source of this shingle discoloration?

a. Dark shingles have been excessively bleached by a chemical reaction between runoff from acid rain reacting with aluminum in chimney flashing and vents.

b. Algae

c. Lichen

d. Airborne dust and dirt washed away by runoff concentrated below the chimney and vents.

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