Standard laminated glass for structural balustrades commonly uses a PVB (poly vinyl butyl) interlayer, bonded between the toughened glass panels. These examples are 17.52mm (8+1.52PVB+8) and 21.52mm (10+1.52PVB+10) from standard toughened glass. Other thicknesses commonly used are 13.52mm and 25.52mm. Typically edge finish for PVB can vary so samples should be obtained. PVB is not 100% proof against moisture ingress.