Notes on Insulating Old Houses in Hot, Humid Climates (Part 2)

Key Topics

1. Importance of Addressing Moisture
2. Stucco Cladding
3. Concrete Block (CMU) Walls
4. Roof Assemblies and Moisture Control
5. Managing Complex Roof and Wall Junctions

Moisture Considerations

• Moisture is a significant concern in old houses, especially in humid climates.
• Improper insulation without considering moisture can lead to mold and rot.

Stucco Cladding

• Commonly seen in the South, applied to wood-framed walls.
• Usually applied over tar paper:
  • First layer as a bond break.
  • Second layer as the primary water control.
• Problems arise if applied directly to sheathing or single WRB layer.
• Insulated walls with stucco can have more problems (e.g., rot) due to moisture traps.
• Importance of air gaps for drainage and capillary break to promote drying.

Concrete Block (CMU) Walls

• CMU walls absorb and store a lot of water, posing insulation challenges.
• Retrofitting insulation: use dimple mats, interior perimeter drains, or fluid-applied waterproofing to manage moisture.
• Preferred method: Add a water and air control layer outside the block wall, followed by rigid insulation.
• Exterior insulation keeps the block wall dry and prevents thermal bridging.
• Resources: Guide to Moisture Management for Residential Remodels on aerd designs.com.

Roof Assemblies and Moisture Control

• Addressing existing conditions in CMU walls when retrofitting insulation.
• Roof to CMU wall connections are complex, often without capillary breaks.
• CMU absorbs moisture and can cause wood framing to rot if not handled properly.
• Uninsulated buildings managed without capillary breaks; insulated need special attention.

Managing Complex Roof and Wall Junctions

• Need to uncouple roof framing from the block walls to prevent rot:
  • Cut rafters away from the block wall.
  • Use a steel angle to support rafters.
• Termination of dimple mats at roof junctions is critical to manage moisture.
• Dealing with moisture in roof membranes:
  • Extend dimple mats to parapet.
  • Use vented counter flashing.
• Preventing moisture accumulation: uncouple roof membrane, use vapor-permeable membranes over CMU walls, provide vented coping.
• Providing paths for moisture to dry out is essential.

Additional Resources

• Encourages watching part one of the series for foundational knowledge.
• Links to articles and guides for further reading on specific techniques and strategies.

Conclusion

• Importance of proper insulation and moisture management to avoid costly issues like mold and rot.
• Next part of the series will cover Roof Systems in more detail.

Actions

• Watch part one if not seen already.
• Check out related resources and guides for comprehensive understanding.
• Stay tuned for part three by subscribing to the channel.