Patent ID: 8595994

Claim:
An insulating glass unit comprising: a first pane of transparent material; a second pane of transparent material that is generally parallel to the first pane of transparent material; a first spacer positioned between the first pane of transparent material and the second pane of transparent material to define a first between-pane space, the first spacer sealing the first between-pane space from gas exchange with a surrounding environment and holding the first pane of transparent material a first separation distance from the second pane of transparent material; a third pane of transparent material that is generally parallel to the second pane of transparent material; and a second spacer positioned between the second pane of transparent material and the third pane of transparent material to define a second between-pane space, the second spacer sealing the second between-pane space from gas exchange with the surrounding environment and holding the second pane of transparent material a second separation distance from the third pane of transparent material, the second spacer comprising a primary sealant extending from the second pane of transparent material to the third pane of transparent material and a gas diffusion barrier layer, wherein the gas diffusion barrier layer is a continuous strip defining a first terminal end and a second terminal end, and the second terminal end overlaps the first terminal end so as to prevent gas diffusion at a junction between the first terminal end and the second terminal end, wherein the first separation distance is greater than the second separation distance and the first spacer is separated from the second spacer by the second pane of transparent material, and wherein the first between-pane space and the second between-pane space are each filled with an insulating gas.