A building system comprising a floor, walls, and a roof post, each consisting of a set of component parts (10, 20,...), at least one (10, 20) of which comprises at least three superimposed layers (100, 110,...) each comprising at least two structural wood slats (101, 103,...; 111, 113,...), a face of at least one structural slat of one of said layers being in contact with a face of at least one structural slat of an adjacent layer at a contact interface (I 101-111), wherein: - a functional slat, for example intended for thermal and/or sound insulation and/or fire resistance, is interleaved between two structural slats (101, 103) of the same layer; - the floor, the walls, and the roof post are divided into several component parts (10, 20,...) following a division essentially based on the sizing limits of the construction transport standards and thus of the industrial tools allowing the manufacturing of the component parts (10, 20,...); - at least two of said component parts (10, 20) are fastened together through non-adhesive fastening means (F 10-20); - at least two adjacent layers of said superimposed layers of the same component part (100, 110) are held against each other through non-adhesive holding means (M 100-110), at least some of which comprise rod-type assembly members (M 100-110); characterized in that - said contacting faces (101A, 111B) are at least partially provided, at said contact interface (I 101-111), with a set of grooved patterns (R 1) arranged so as to prevent said structural slats (101, 111) from sliding relative to each other along at least a first locking axis (B 1); - the grooved patterns (R 1) comprise a first series of parallel grooves (R 1) and a second series of parallel grooves (R 2), oriented along a first axis (Ox) and a second axis (Oy) not parallel to each other, respectively; - the grooved patterns (R 1, R 2) have a width at the base between 1 and 15 millimeters; and - the grooved patterns have substantially triangular sections. - a functional slat, for example intended for thermal and/or sound insulation and/or fire resistance, is interleaved between two structural slats (101, 103) of the same layer; - the floor, the walls, and the roof post are divided into several component parts (10, 20,...) following a division essentially based on the sizing limits of the construction transport standards and thus of the industrial tools allowing the manufacturing of the component parts (10, 20,...); - at least two of said component parts (10, 20) are fastened together through non-adhesive fastening means (F 10-20); - at least two adjacent layers of said superimposed layers of the same component part (100, 110) are held against each other through non-adhesive holding means (M 100-110), at least some of which comprise rod-type assembly members (M 100-110); characterized in that - said contacting faces (101A, 111B) are at least partially provided, at said contact interface (I 101-111), with a set of grooved patterns (R 1) arranged so as to prevent said structural slats (101, 111) from sliding relative to each other along at least a first locking axis (B 1); - the grooved patterns (R 1) comprise a first series of parallel grooves (R 1) and a second series of parallel grooves (R 2), oriented along a first axis (Ox) and a second axis (Oy) not parallel to each other, respectively; - the grooved patterns (R 1, R 2) have a width at the base between 1 and 15 millimeters; and - the grooved patterns have substantially triangular sections.