National Home Inspector Practice Exam 2026 - Free Home Inspector Practice Questions and Study Guide

The approximate "R" value of 12 inches of loose fill fiberglass insulation is typically around R30. The "R" value is a measure of thermal resistance, with higher values indicating better insulating properties. Loose fill fiberglass insulation generally has an R-value of about R2.2 to R4.3 per inch, depending on its density and specific formulation. Therefore, when you multiply the average R-value range by 12 inches, the resulting total falls within the vicinity of R30.

This makes the option of R30 valid as it accurately reflects the insulating efficiency of this type of material spread over the specified thickness. Understanding insulation R-values is crucial for home inspectors, as they assess energy efficiency and compliance with building codes, ensuring that homes are appropriately insulated to meet homeowners' needs for comfort and energy savings.