It is becoming more popular this days owing to its ease in analysis and economy generated from decreased depth from punching ( no punching at all since beams are available between columns). Ribbed mat is an inverted solid slab system. Meaning the beams are upstanding and the load is acting in upward direction. usually used under one or more of the following conditions( p.c. varghese) : when there is an unsymmetrical load arrangement on columns when the column spacing are so large that the depth of the slab required for a flat slab( solid mat) mat becomes too large. when the foundation soil is not very uniform and we expect soft spots in the foundation area. The foundation consists slab and an upstanding beam. It is more rigid than solid mats and more efficient in distribution of loads( P.c varghese) .