A deformable slat system for a building construction has one or more deformable slats (1). At least one of the aforementioned slats (1) has two slat parts (Ia, Ib) which are joined together in such a way that they are hingeable about a hinge line (2). This slat (1) is bendable and/or twistable in each first position where the slat parts (Ia, Ib) are hinged at a straight angle or a zero angle with respect to one another and is rigidified in each second position where the slat parts (Ia, Ib) are hinged at an angle differing from the straight angle or zero angle with respect to one another. The slat system includes means (13a, 13b, 19a, 19b, 14, 15, 16) for bringing the aforementioned slat (1) selectively into a first or a second position, and for bringing a slat (1), which has been brought into a first position, into a bent and/or twisted position. Furthermore, a slat (1) is provided for a slat system of this type, and also a building construction is provided with a slat system of this type.