A method and system for forming an insulation package for use in a vacuum insulated structure is provided. A slurry containing a liquid and an insulation material is formed. The slurry can be supplied to an envelope under vacuum, wherein the envelope is gas-permeable and permeable to the liquid. At least a portion of the liquid is drawn through the envelope and at least a portion of the insulation material is retained within the envelope to form an insulation package. One or more insulation packages can be disposed within an insulating cavity and the insulating cavity can be evacuated to decrease a pressure therein to form a vacuum insulated structure.