Sarking is a layer of flexible insulation typically installed under roof tiles when a home is being constructed.It consists of aluminum foil laminated onto paper or plastic backing with a flame retardant adhesive and fibreglass reinforcing mesh, and is manufactured in sheet form.Sarking performs a dual function, helping to keep your home insulated from the heat of summer whilst retaining warmth in the winter.t consists of aluminum foil laminated onto paper or plastic backing with a flame retardant adhesive and fibreglass reinforcing mesh, and is manufactured in sheet form. Sarking performs a dual function, helping to keep your home insulated from the heat of summer whilst retaining warmth in the winter.