What type of wall is prone to collapse or peel away as the wall behind it burns?

The correct answer is brick veneer because this type of wall is constructed from a single layer of brick that does not serve a structural purpose; instead, it acts primarily as a decorative facade. When exposed to intense heat from a fire, the materials of the brick veneer can experience thermal expansion and loss of adhesion to the underlying structure. As the wall behind it burns, the adhesive properties can weaken, leading to the brick veneer collapsing or peeling away, especially if not adequately anchored.

In contrast, load-bearing walls are integral to the structural integrity of a building and are designed to support heavy loads, making them less prone to collapse in a fire scenario as they are generally constructed to withstand thermal stresses. Concrete block walls, while they can experience cracking under extreme heat, are typically more resilient and can remain stable during a fire. Timber frame walls, although they can burn and may eventually collapse under severe conditions, tend to have more integrity than a non-structural veneer under fire conditions due to their framing and support nature.

Thus, the unique construction characteristics of brick veneer make it particularly vulnerable in the context of fire, leading to its potential to collapse or detach as other materials within the wall assembly are compromised by heat.