by Kenton Shepard and Nick Gromicko, CMI®
The purpose of the series “Mastering Roof Inspections” is to teach home inspectors, as well as insurance and roofing professionals, how to recognize proper and improper conditions while inspecting steep-slope, residential roofs. This series covers roof framing, roofing materials, the attic, and the conditions that affect the roofing materials and components, including wind and hail.
Biological Growth (continued)
Moss is a greenish plant. It can grow more thickly than algae. Moss attaches itself to the roof through a shallow root system that can be freed from shingles fairly easily with a brush.
Moss deteriorates shingles by holding moisture against them, but this is a slow process. Moss is mostly a cosmetic issue and, like algae, is a safety issue for those walking the roof.
Lichens are composite organisms consisting of a fungus and a photosynthetic partner, such as green or blue-green algae.
Lichens bond tightly to the roof, and when they’re removed from asphalt shingles, they may take granules with them. Damage from lichen removal can resemble blistering.
"Tobacco-juicing" is the brownish discoloration that appears on the surface of shingles, under certain weather conditions. It’s often temporary and may have a couple of different causes. After especially long periods of intensely sunny days, damp nights and no rain, water-soluble compounds may leach out of asphalt and be deposited on the surface of the shingle. Another way tobacco-juicing appears is when, under those same weather conditions, particulates from air pollution plate out on the shingle surfaces.
Learn how to master a roof inspection from beginning to end by reading the entire InterNACHI series: Mastering Roof Inspections.
Take InterNACHI’s free, online Roofing Inspection Course
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