Four listener questions. Four very different building science challenges. One highly technical episode.

Steve, Jake, and Pete tackle a collection of building puzzles that span foundations, roofs, wall assemblies, and moisture management. The discussion starts with expansive soils and why successful construction often depends on engineered foundation systems designed to accommodate soil movement. From there, the crew examines attic radiant barriers, where they work best, and why climate matters when evaluating their performance.

The conversation then shifts to a cold-climate stucco retrofit involving exterior rigid insulation, reinforcing a core building science principle: prioritize the four control layers in the right order—water first, airtightness second, drying potential third, and thermal control fourth. Finally, they unpack the risks of a “diaper wall” assembly, where moisture-sensitive materials become trapped between low-permeance layers, and discuss how weather protection and airtightness can reduce those risks.

A highly technical episode packed with practical problem-solving, building science fundamentals, and real-world application.

Pete’s Resources:

• Post-Tension Slabs for Expansive Soils
• Evolution of Foundation Design for Expansive Soils
• ORNL Thermal Performance Evaluation of Attic Radiant Barrier Systems
• Building America Solution Center – Attic Radiant Barriers
• EPA Moisture Control Guidance
• GBA – Vapor Profiles Help Predict Whether a Wall Can Dry