Mold growing at the underside of attic sheathing is an all too common problem. This is generally caused by excessive humidity in the attic and a lack of ventilation. Bath fans discharging directly into the attic, overuse of humidifiers and insufficient roof ventilation are all contributing factors. Some inspectors may try too sell you a mold test. If you have this condition you can skip the test and go directly to remediation. It doesn’t matter what kind of mold it is. The excessive moisture needs to be removed. Options for mitigation could include cleaning and treatment of the contaminated plywood or outright removal of the roof coverings and discarding the contaminated sheathing. That depends on severity, accessibility and the age of the roof. Either way it is usually a significant expense. All work should be done by reputable contractors with certification in mold mitigation. Bleach is never the answer.
David Tamny is a Registered Architect and an ASHI Certified Home Inspector with over 15 years of home inspection experience. He will provide a competent and thorough evaluation of the condition of the systems and components of a home. Life expectancy, materials used, construction quality, and deferred maintenance are some of the considerations of the inspection.