Abstract: The invention provides a construction element having a front face (1), a back face (2), a top face (3), a bottom face (4) and end faces (5) and (6). Each of the top (3), bottom (4) and end faces (5) and (6) contains a channel (7) having side walls (8) joined by a base (9) and arranged so as to surround the periphery of the construction element. An aperture (12) is formed between the top face (3) and bottom face (4). The aperture (12) is hexagonal in cross-section. In each channel (7), each side wall (8) forms an angle of 120 degrees with the base of channel (7).