Abstract: A multi-panel thermal insulated glass unit is supported within an outer frame of U-shaped cross-section by a molded-in-place filler of silicone rubber. The latter forms a resiliently yieldable cushion which supports the glass unit in spaced relation from the frame and which enables limited floating of the glass unit within the frame to isolate the glass unit from shock and vibration imparted to the frame. As a result, the insulated glass unit may be used reliably in a heavy duty off-the-road construction vehicle without any appreciable risk of shock and vibration causing glass breakage or rupture of the airtight seal between the glass panels.