A spa having a rotomolded unibody shell defining a basin, an upper edge surrounding the basin, a peripheral wall, a cavity between the basin and the peripheral wall. The peripheral wall having at least one opening leading to the cavity. The spa including a frame, decoupled from the spa shell, in the form of a plurality of individual components introducible into the cavity within the shell via the opening in the shell, and assemblable to one another inside the shell. The frame including side beams and couplers in continuous abutment with the upper edge of the shell, offering a superior structure and support.