A foam wall structure includes a frame, at least one primary support member, a slab of polyiso board and a foam layer. The frame can include: a first member, a second member spaced apart from the first member; and two side members extending between the first and second members. The frame defining a front frame surface and an opposite rear frame surface. The at least one primary support member can be positioned between the two side members and extend between the first and second member. The primary support member defines a front support surface and an opposite rear support surface. The slab of polyiso board may be attached to the front frame surface. The foam layer can be received within at least a portion of the frame and overlies the front surface of the primary support member. A method of making a foam wall structure and a pre-fabricated wall is also disclosed.