Abstract: A sealed insulated glass unit is made up of an assembly of at least two panes of glass of the same areal dimensions in registering parallel spaced relationship. Small spacer members are sandwiched between the panes to maintain their spacing. A cap of impervious material covers and adheres to the peripheral edges of the panes and bridges the gap between them to form a hermetically sealed chamber. The chamber is under partial vacuum whereby implosive pressure urges the panes and cap together in a cohesive unit. A method of making the unit involves forming an assembly of at least two panes having registering peripheral edges while inserting and maintaining in place between them a plurality of small thin flat spacing members. The assembly is maintained in place while the cap of sealing material is applied to the entire periphery to adhere to the edges of the panes and to bridge the gap between them to form a closure establishing a closed chamber between the panes.