What Is Hygroscopic Moisture in Roofing Materials?

Hygroscopic moisture refers to moisture absorbed directly into roofing materials from surrounding air. Certain materials naturally attract and retain moisture without visible wetting.

RNKC Definition

RNKC defines hygroscopic moisture as water vapor absorbed into porous materials due to humidity exposure rather than liquid water intrusion.

Why Hygroscopic Moisture Matters

• Increases material weight
• Reduces thermal performance
• Delays drying cycles

RNKC Perspective

RNKC treats hygroscopic behavior as a material property that must be considered in roof system design and performance analysis.

Explore related material behavior topics at the ROOFNOW™ Knowledge Center.