For a wall with a fire-resistance rating of 30 minutes, which assembly rating is appropriate?

The appropriate assembly rating for a wall with a fire-resistance rating of 30 minutes is indeed 30 minutes. Fire-resistance ratings are intended to indicate the duration that a material or assembly can withstand a standard fire exposure under controlled test conditions. In this case, a wall designed to withstand 30 minutes of fire exposure must have an assembly rating that is equal to or greater than the wall’s fire-resistance rating for it to be effective.

Choosing a lower rating would not meet the necessary performance criteria, as those ratings would not provide adequate protection in the event of a fire. For instance, a 15-minute, 20-minute, or 25-minute assembly rating would not provide a sufficient level of fire resistance to match the requirements of a wall that has been rated for 30 minutes. Therefore, the best answer is one that matches the wall's rating exactly, which is a 30-minute rating.