A building element for timber wall and ceiling structures and the producing method thereof solve a problem of an easily producible building element that is based on a cross laminated massive timber plate (18) assembled from a layer of outer lamellas (2) and (4) and of an optional number of inner lamellas (3, 4, 5) with vertical ribs (1) or (1, 1') placed at certain spacing between the outer lamellas (2) in an optional sequence. In the compartments between the ribs (1) or (1, 1') insulation infill (19) can be placed and the whole setup can be closed with a cover plate (20). For the pre-stressed structures of building elements, the vertical ribs (1) and/or (1') are curved in the tangential direction of the longitudinal axis by an optional distance of (X). The last layer of the outer lamellas (2) with the intermediate vertical ribs (1) and (1') is glued and laid to the former layer of inner lamellas (3) preferentially simultaneously and fully and within the given sequence also as pressed in the press together w
