Illinois Roofing Practice Exam 2026 – Complete Exam Preparation Guide

Vapor drive refers to the movement of water vapor within a roofing system, which is primarily influenced by differences in vapor pressure. This phenomenon occurs when there is a higher concentration of water vapor in one area compared to another, causing moisture to migrate from areas of high vapor pressure to areas of low vapor pressure. Understanding vapor drive is crucial in roofing design and installation, as it can impact the durability and performance of the roofing materials.

By controlling vapor drive, roofing systems can effectively manage moisture, preventing issues such as condensation that could lead to mold growth or structural damage. This concept is particularly significant in climates where temperature variances create significant pressure differences, making it essential for roofing professionals to be aware of vapor drive when designing and installing roofing systems. The other options do not accurately describe the concept; they pertain to other phenomena related to water, air, and heat but do not encapsulate the specific principles of vapor movement driven by pressure differences.