What type of barrier must be installed when foam plastic insulation is in proximity to certain spaces?

The correct answer is that a thermal barrier must be installed when foam plastic insulation is near certain spaces, particularly in areas where it may be exposed to high temperatures or potential flame hazards. Thermal barriers serve to protect the insulation material from ignition in case of a fire, ensuring that the foam does not act as a fuel source and that it complies with fire safety codes.

In construction, thermal barriers are typically implemented using materials that can withstand high temperatures for a specified duration, reducing the risk of heat reaching the foam insulation. This is crucial because foam plastic insulation can melt or ignite easily, hence the need for such protection in specific applications, such as in walls near living spaces or in commercial buildings.

The other types of barriers mentioned serve different purposes. A vapor barrier is used to prevent moisture from moving through building assemblies, while a sound barrier aims to reduce noise transmission between spaces. A moisture barrier is specifically intended to prevent the intrusion of water. While these barriers are important in their contexts, they do not address the fire safety and temperature concerns associated with foam plastic insulation like a thermal barrier does.