Quick Answer
Cellulose insulation is generally not recommended for exterior walls due to its potential to become saturated and lose its insulating properties when exposed to moisture.
Exterior Wall Risks
Cellulose insulation is made from recycled paper products, which can be prone to moisture absorption when exposed to the elements. Exterior walls are more susceptible to water damage and condensation, which can compromise the integrity of cellulose insulation. This is why it’s crucial to use materials specifically designed for exterior wall insulation, such as rigid foam board or exterior-grade fiberglass batts.
Recommended Alternatives
If you’re looking for eco-friendly options for exterior wall insulation, consider using recycled denim or wool batts, which are more resistant to moisture and better suited for exterior applications. These materials are also a good choice for exterior walls with rain-screen systems or similar weather-resistant barriers. For example, a 3.5-inch thick layer of recycled denim batts can provide R-19 insulation, while a 4-inch thick layer of wool batts can achieve R-23.
Design Considerations
When designing an exterior wall insulation system, consider factors such as local building codes, climate, and wind loads. Ensure that the chosen insulation material is compatible with the exterior cladding and weather-resistant barrier. For instance, if you’re using a rain-screen system, select an insulation material that’s compatible with the air gap and drainage requirements.
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