Rigid wall: Load bearing vertical wall. Can be made with aerated concrete blocks, poured concrete, concrete panels, perforated cell elements in concrete or brick. With REI classification.

Flexible wall: Non load bearing vertical wall. Can be made with a metal structure insulated with rock wool and covered with 2 plasterboard layers on each side or with special solid gypsum blocks with interlocking shaped edges. With EI classification.

Floor: Load bearing horizontal structural element. Can be made with aerated concrete blocks, poured concrete. With REI classification.