Which type of construction allows for the installation of thermal and acoustical insulation with a maximum flame spread index of 25?

The correct answer indicates that both Type I and Type II construction allow for the installation of thermal and acoustical insulation with a maximum flame spread index of 25. This is significant because both types are designed for enhanced fire safety and can utilize insulation materials that meet this stringent flame spread requirement.

Type I construction refers to buildings made with noncombustible materials, which can better resist fire spread and help protect the structure and its occupants. Meanwhile, Type II construction also includes noncombustible materials but may incorporate lightweight construction elements. The use of insulation with a maximum flame spread index of 25 in both types underscores a commitment to maintaining fire safety standards without compromising thermal and acoustic performance.

This capability is particularly critical in commercial buildings, where minimizing fire risk while ensuring energy efficiency and sound control is essential to meet both safety regulations and occupant comfort. Thus, both types of construction can accommodate these insulation materials, making them favorable for various applications in building design and renovation.