Home Inspection State Practice Exam

What is the most likely cause of rusted nails penetrating roof sheathing combined with moisture stains and fungal growth?

1. Roofing material deterioration

2. Air leaking from the house into the attic

3. Condensation in the attic

4. Improper insulation

The correct answer is: Air leaking from the house into the attic

The scenario presented involves rusted nails penetrating roof sheathing along with moisture stains and fungal growth, which points to a significant moisture issue within the attic space. Air leaking from the house into the attic is a likely cause because it can introduce warm, humid air that condenses on cooler surfaces, such as roof sheathing. When this humid air enters the attic, it raises the relative humidity levels, leading to condensation. The presence of moisture creates an environment conducive to the development of fungal growth, which can cause visible stains and deterioration of materials, such as the rusting of nails used to secure the roofing components. As the nails rust, they can corrode to the extent that they lose their grip and might start penetrating through the roof sheathing. In summary, the introduction of warm, moist air from the living spaces below into the attic is a key factor in promoting moisture-related issues, thereby leading to the observed conditions of rusted nails, moisture stains, and fungal growth.