This tool compares the two heavyweights of the tiny house world: Closed Cell Spray Foam (the structural king) vs. Sheep’s Wool (the moisture management queen). It calculates the resulting R-Value based on your wall depth and visualizes the critical trade-off: Rigidity vs. Breathability.
It includes a comprehensive “Science of the Wall” section at the bottom to explain why these factors matter specifically for mobile structures.
Insulation Analyzer: Foam vs. Wool
Compare R-Value, Structural Strength, and Moisture Control.
1. Wall Configuration
Enter dimensions to see the comparison.
Thermal Resistance (R-Value)
The Science of the Wall
Structural Rigidity (The “Glue” Effect)
Closed Cell Foam is rigid. When sprayed, it adheres tenaciously to the studs and sheathing, effectively gluing your entire wall assembly into a monolithic block. This increases the “Racking Strength” (resistance to wind/sway) by up to 300%. For mobile tiny homes constantly subjected to earthquake-like highway vibrations, this is a massive durability advantage.
Wool creates no structural bond; the frame must stand 100% on its own.
Moisture Management (Hygroscopic vs. Hydrophobic)
Sheep’s Wool is hygroscopic. The fibers can absorb up to 30% of their weight in water vapor from the air (humidity) and release it later when the air is dry, all without feeling wet or losing R-value. This acts as a natural humidity buffer, preventing mold in tight spaces.
Foam is a vapor barrier. It blocks moisture completely. If water gets trapped inside the wall (from a leak), it cannot dry out, leading to rot.
Weight Considerations
Both materials are relatively light compared to wood or metal, but Spray Foam is denser (~2.0 lbs/ft³) than Wool batting (~1.5 lbs/ft³). However, the difference is usually negligible for the structural benefits gained.