Which construction practice contributes to mold growth in modern buildings?

More tightly sealed building envelopes contribute to mold growth in modern buildings because they can trap moisture within the structure. In a tightly sealed building, there is limited airflow, which prevents moisture from escaping and can lead to higher humidity levels indoors. When moisture accumulates in the walls, ceilings, or other hidden areas, it creates an ideal environment for mold to thrive.

In contrast, the other practices mentioned are less directly related to mold growth. For instance, increased window sizes may improve ventilation if designed properly, while open floor plans typically allow for better air circulation, reducing moisture buildup. Wood-based materials can be susceptible to mold but are not inherently responsible for mold proliferation if the building envelope is well-managed. Thus, the sealing aspect is the key factor in promoting mold growth.