Which material may be part of the 2-hour fire separation between townhouses?

The material that would appropriately serve as part of the 2-hour fire separation between townhouses is roof sheathing that is covered by 5/8 inch Type X gypsum board for 4 ft. This selection meets the necessary fire-resistance rating required for a 2-hour fire separation, as Type X gypsum board is specifically designed to provide enhanced fire resistance.

In the context of building codes and fire safety, a 2-hour fire separation indicates that the material must be able to withstand fire exposure for at least two hours without allowing flames or heat to penetrate. The thickness of 5/8 inch for Type X gypsum board is critical for providing adequate fire resistance and meeting the required fire rating. This composite construction creates a fire-resistive barrier, enhancing safety between units and lowering the risk of fire spreading from one townhouse to another.

The inclusion of Type X gypsum board also highlights the importance of using materials that are both compliant with safety standards and effective in enhancing the overall fire protection strategy in residential settings. Thus, this option successfully aligns with both practical application and adherence to building codes concerning fire separations in multi-family dwellings.