What should the door assembly rating be for a wall with a fire-resistance rating of 2 hours?

The appropriate door assembly rating for a wall with a fire-resistance rating of 2 hours should be 2 hours as well. This is because fire doors are required to have a rating that matches or exceeds the fire-resistance rating of the wall in which they are installed to maintain the integrity of the fire-rated assembly.

When a wall has a fire-resistance rating of 2 hours, it indicates that the wall is designed to withstand fire for that duration. The door assembly plays a critical role in protecting openings in these walls, and therefore must also be rated to provide a comparable level of fire protection.

Choosing a door assembly rating less than 2 hours compromises the wall's effectiveness and could lead to catastrophic failures during a fire. A rating of 1 hour or 1.5 hours would not provide sufficient protection to match the wall’s resilience, creating a safety hazard. Likewise, a 3-hour rating is unnecessarily excessive for a 2-hour wall, as building codes typically do not require a door's rating to exceed that of the surrounding wall.

In sum, the correct answer aligns with the need for consistency between the wall and door assembly fire ratings to effectively contain fire and smoke, thus ensuring safety and compliance with fire safety standards.