Which of the following materials is commonly used as fire retardant treated wood?

Fire retardant treated wood is wood that has been specially treated with fire retardant chemicals to reduce its combustibility and improve fire performance. This kind of treatment can be applied to various types of wood products to enhance fire safety in construction.

Plywood, OSB (Oriented Strand Board), and particle board can all be treated to achieve fire retardant properties. Each of these materials can be used in various applications within buildings, often depending on the specific requirements of a project or building code.

Since all three materials can be effectively treated to meet fire safety regulations, the answer indicating that all of the listed materials are commonly used as fire retardant treated wood is accurate. This is an important consideration for residential building contractors who must ensure compliance with local fire codes and standards, making fire retardant treated wood a crucial aspect of safe building practices.