The invention creates a foldable wall structure for extending the interior space of transportable constructions, in particular a vehicle such as a camper van. The foldable wall structure has a first foldable wall which, in the folded-out state, forms a base wall of the wall structure, and a second foldable wall which, in the folded-out state, forms a cover wall of the wall structure. The foldable wall structure has a foldable fourth wall and a foldable fifth wall, which, in the folded-out state, form a first and a second side wall; the wall structure also has a frame structure, in which the wall structure has a third wall that can be translationally shifted relative to the folded-in first wall, the third wall forming an outer wall of the wall structure in the shifted state.