Final answer:
A wall that is built of two materials without an air space between the inner and outer layer is called a composite wall.
Step-by-step explanation:
A wall that is built of two materials without an air space between the inner and outer layer is called a composite wall. This type of wall construction is commonly used to optimize the properties of both materials. One example is a wall with an internal structure made of concrete and an external cladding made of brick or stone.