An insulating unitless window sash includes a sash frame made of four linear sash members having their mitered edges joined together. Each of the sash members in cross section includes a peripheral surface, a first and outer side walls and a first groove spaced from a second groove. Each of the grooves has a base and spaced walls. The base of the first groove is spaced a greater distance from the peripheral surface than the base of the second groove. Peripheral and marginal edges of a first sheet are in the first groove and peripheral and marginal edges of a second sheet are in the second groove. A shim is mounted on the sash frame adjacent the outer surface of the first sheet to give a balance configuration.A method of fabricating the insulating unitless sash is also disclosed.