What is a common drawback of fiberglass batt insulation methods for foundation walls?

Fiberglass batt insulation methods for foundation walls indeed have some drawbacks, particularly concerning their effectiveness and suitability across different climates. The option indicating they are no longer recommended in any climate is relevant because fiberglass batts can trap moisture, especially in areas prone to high humidity or flooding. This can lead to issues such as mold growth and degradation of the insulation material over time. Additionally, in colder climates, the performance of fiberglass batt insulation can be compromised if they allow heat to escape or do not create an effective air barrier, thus reducing energy efficiency.

By contrast, while fiberglass batts can be cost-effective, they do require proper installation to be effective, and they are not exclusively limited to warmer climates, nor do they necessitate frequent maintenance if installed correctly. Therefore, the recognized issues with fiberglass batt insulation in diverse climates are fundamental in understanding why it may not be recommended broadly across all environmental conditions.