Masonry parapet wall is a vertical extension of the building’s wall structure above its roofline, usually enclosing it. It can be also erected around the balconies and terraces as a protective barrier or serve as a firewall dividing two adjoining buildings or apartments. Sometimes used on buildings for purely aesthetic reasons. The main purpose of having parapet walls around your low slope roof is to prevent the roof’s edges from being uplifted by heavy winds. Parapet walls significantly reduce air pressure differences along the roof edges minimizing up-lifting force of the wind.