This article summarizes the official Earthaus Breathable Sealer Water Vapor Permeability Test Results, adapted for clarity and ease of reference. To view the full report, see the Breathable Sealer Water Vapor Permeability Testing Results (PDF).
Testing Overview
Conducted by: Braun Intertec Corporation | Concrete Science, Chicago, IL
Date: April 8, 2025
Standard: ASTM D6490 — Wet Cup Method
Purpose: Evaluate the effect of Earthaus Breathable Sealer on water vapor permeability when applied over Earthaus PHL Binder.
Results — Water Vapor Permeance (Perms)
Material Tested | Permeance (Perms) |
Earthaus PHL Binder (unsealed) | 18.2 – 19.8 |
Earthaus PHL Binder + Breathable Sealer | 15.1 – 15.9 |
European NHL 3.5 | 12.5 |
European NHL 5 | 9.5 – 11.0 |
Cement Stucco | 3.0 – 7.0 |
Key findings:
Water vapor permeance: 15.1 – 15.9 perms
Water vapor transmission rate (WVT): 6.2 – 6.5 grains/h·ft²
What These Results Mean
Minimal reduction: The Breathable Sealer reduces vapor permeability only slightly compared to unsealed Earthaus PHL.
Superior to other materials: Even with the sealer, permeability remains higher than NHL 3.5, NHL 5, and cement stucco.
Balanced protection: Provides surface protection while still allowing wall systems to dry effectively.
Conclusion
Earthaus Breathable Sealer maintains high breathability when applied over lime plaster.
Ideal for natural wall systems where moisture permeability and protection are both needed.
© 2025 Earthaus Plaster LLC. All rights reserved.
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